GB2475479A

GB2475479A - Borehole reactor

Info

Publication number: GB2475479A
Application number: GB0920144A
Authority: GB
Inventors: David Dorab Jamshed Antia
Original assignee: DCA CONSULTANTS Ltd
Current assignee: DCA CONSULTANTS Ltd
Priority date: 2009-11-18
Filing date: 2009-11-18
Publication date: 2011-05-25
Anticipated expiration: 2029-11-18
Also published as: GB0920144D0; GB2475479B

Abstract

An apparatus constructed from casing, which is used for one or more of catalytic reactions, non-catalytic reactions, fluid separation, filtration and adsorption/absorption. The reactor is constructed within the borehole from casing, or is constructed using one or more pre-formed units (made from casing). All or part of the reactor is located within a borehole or underground or in water. The reactor comprises at least one reaction zone and a membrane unit constructed using casing segments. The invention is used to process a single fluid group or two or more groups of fluids into products. A fluid group can contain more than one fluid. It is suitable for use in sites with a compact footprint, for the treatment, or processing, of high volumes of fluid, and for both low and high pressure operations. The reactor can contain more than one reaction zone. The invention can be constructed in a new borehole, or can be used to convert an existing borehole into a reactor.

Description

BOREHOLE REACTOR

DOCUMENTS CITED

PATENT DOCUMENTS CITED

US 4618732 Direct conversion of natural gas to methanol by controlled oxidation, 21 October 1986, Gesser, H. D., Hunter, N.R., Morton, L. 2. GBO8 17567.1 Capture of Carbon Oxides, 25th September, 2008, Antia, D.D.J.

OTHER DOCUMENTS CITED

I. Matsuura, 1. 1993. Synthetic membranes and membrane separation processes. CRC Press, ISBN-13:978-0849342028.

2. Mulder, M., 1996. Basic principles of membrane technology. Kiuwer Academic Publishers. Dordrecht. ISBN: 0-7923-4247-X.

3. Yan, Z.F., Ding, R.G., Song, L.H., Qian, L., 1998. Mechanistic study of carbon dioxide reforming with methane over supported nickel catalysts. Energy Fuels, 12, 1114 -1120.

4. Antia, D.D.J. & Seddon, D. 1998 Low cost 10 MMCF/D gas to syncrude plant for associated gas. OTC Paper 8901 5. Filippov, A., Mack, R., Cook, L., York, P., Ring, L., McCoy, 1., 1999. Expandable Tubular Solutions, SPE Paper 56500 6. Qian, L., Yan, Z.F., 2003. Study on the reaction mechanism for carbon dioxide reforming of methane over supported nickel catalyst. Chinese Chemical Letters, 14, 1081 -1084.

7. Lyons, W.C., Plisga, G.J., 2004. Standard handbook of petroleum and natural gas engineering. Gulf Professional Publishing. ISBN-I 3: 978-0750677851 8. Steynberg, A., Dry, M., 2004. Fischer-Tropsch Technology. Elsevier. ISBN-13: 978- 0444513540.

9. Mazunider, S., van Hemert, P., Busch, A., Wolf, K-H, A.A., Tejera-Cuesta, P., 2006. Flue gas and pure CO2 sorption properties of coal: a comparative study. International Journal of Coal Geology, 67, 267 -279.

10. Misstear, B., Banks, D., Clark, L., 2006. Water wells and boreholes. Wiley., ISBN: 978- 0-470-84989-7.

11. Saka, S., Minami, E., 2006. A novel non-catalytic biodiesel production process by supercritical methanol as NEDO "high efficiency biodiesel conversion project". Paper C- 041(P), 6p. The 2 Joint International Conference on sustainable energy and environment (SEE 2006), 2 1-23 November, 2006, Bangkok, Thailand.

12. Jadhav, P.D., Chatti, R.V., Biniwale, R.B., Labhsetwar, N.K., Devotta, S., Rayalu, S.S., 2007. Monoethanol amine modified zeolite 13X for CO2 adsorption at different temperatures. Energy Fuels, 21, 3555-3559.

13. Green, D.W., Perry, R.H., 2008. Perry's chemical engineers handbook. McGraw Hill, New York, ISBN: 978-0-07-142294-9.

14. Scholes, C.A., Kentish, S.E., Stevens, G.W., 2008. Carbon dioxide separation through polymeric membrane flue gas applications. Recent Patents on Chemical Engineering, 1, 52-66.

15. Li, Y., Xiao, R., un, B., Zhang, H., 2008, Experimental study of the reforming of methane with carbon dioxide over coal char. International Journal of Chemical Reactor Engineering, 6, A16.

16. Lide, D.R., 2008. CRC Handbook of Chemistry and Physics, 89th Edition 2008-2009.

CRC Press, ISBN-13: 978-1-4200-6679-1 17. Song, Q., Xiao, R., Li, Y., Shen, L., 2008. Catalytic carbon dioxide reforming of methane to synthesis gas over activated carbon catalyst. md. Eng. Chem. Res., 47, 4349 -4357.

18. Nakagawa, K., Kikuchi, M., Nishitani-Gamo, M., Oda, H., Gamo, H., Ogawa, K., Ando, 1., 2008. CO2 reforming of CH4 over Co/oxidised diamond catalyst. Energy Fuels, 22, 3566-3570 19. Michalkiewicz, B., Sreriscek-Nazzal, .1., Ziebro, J., 2009. Optimisation of synthesis gas formation in methane reforming and carbon dioxide. Catalysis Letters, 129, 142-. 148.

20. Chatti, R., Bansiwal, A.K., Thote, J.A., Kumar, V., Jadhav, P., Lokhande, S.K., Biniwale, R.B., Labhsetwar, N.K., Rayalu, S.S., 2009. Amine loaded zeolites for carbon dioxide capture: Amine loading and adsorption studies. Microporous and Mesoporous Materials, 121, 84-89.

21. Belmabkhout, Y., Sayari, A., 2009. Effect of pore expansion and amine functionalisation of mesoporous silica on CO2 adsorption over a wide range of conditions. Adsorption, 15, 318 -328.

22. Ghorbanzadeh, A.M., Lottalipour, R., Rezaer, S., 2009. Carbon dioxide reforming at near room temperature in low energy pulsed plasma. International Journal of Hydrogen Energy,34,293-298.

FIELD OF INVENTION

There is a requirement for a small footprint apparatus for one or more of catalytic processes, non-catalytic processes, filtration processes, adsorption processes, absorption processes, and separation processes, which can be used to process gases or liquids. This invention creates a small footprint plant by placing all, or part, of the reactor within a borehole. There is also a requirement to be able to undertake high pressure processes in a safe environment. The invention is able to undertake these high pressure processes within a borehole.

BACKGROUND TO THE INVENTION

The invention is a borehole reactor, which provides a common solution to three problems: (i) Removal of anthropogenic carbon oxide emissions from power stations, incinerators, chemical processes, carbonisation processes, refineries, combustion processes, manufacturing processes, and other anthropogenic sources. The existing technology is based around a. gas cleaning approaches 1. membrane separation (e.g. Mulder, 1996; Scholes et al., 2008), 2. CO2 sorption (e.g. Jadhav et al., 2007; Chatti et al., 2009; Belmabkhout and Sayari, 2009) b. catalytic reaction approaches including 1. CO2 reforming (with Cth) to form synthesis gas (a gas containing CO and H2, e.g. CH4 + CO2 2CO + 2H2 (e.g. Yan et al., 1998; Qian and Yan, 2003; Li et al., 2008; Song et al., 2008; Nakagawa et al., 2008; Michalkiewicz et al., 2009; Ghorbanzadeh et al., 2009), 2. CO2 (and CO) polymerisation with CH4, CXHYOZ and H2 to form organic chemicals and oil (e.g. Steynberg and Dry, 2004; GBO8 17567.1).

3. Steam reforming, oxidation and partial oxidation to remove CH4 by converting it to CO or CO2 (e.g. Antia and Seddon, 1998; Steynberg and Dry, 2004).

(ii) Water treatment, including desalination, foul water treatment, storm water treatment, treatment of groundwater, treatment of riparian water, etc..

(iii) Processing of natural gas (including stranded gas), and associated gas to one or more of oil, organic chemicals, and water, in an onshore or offshore environment (Antia and Seddon, 1998).

Existing surface based reactors can be used to produce fluids, which are subsequently disposed of in a borehole, or can be used to produce products from fluids, which have been produced from a borehole.

The prior art is not used to undertake specific chemical reactions within the borehole. This invention undertakes chemical reactions within the borehole and can be constructed to undertake fluid separation processes.

Definitions Absorption: The term absorption refers to all absorption and all adsorption processes. The term absorption also includes desorbent and desorption processes. Absorption processes relate to the absorbing (swallowing up) of a fluid into a chemical, or substance, or structure. Non-limiting examples of absorption processes are provided in Green and Perry (2008).

Adsorption: The term adsorption refers to all adsorption and all absorption processes. The term adsorption also includes desorbent and desorption processes. An adsorbent is a material, which is able to adsorb one or more components from the fluid. A desorbent is a material, which is able to desorb one or more absorbed/adsorbed components into a fluid. Absorbents/adsorbents are chemicals, which can remove a fluid component by attaching them to a chemical or structure within the adsorbent bed.

Absorbed/adsorbed chemicals are recovered (desorbed) by changing the chemical environment or the temperature, or pressure, or a combination thereof. Adsorption and adsorbent includes ion exchange sorption processes. Non-limiting examples of adsorption and ion exchange processes are provided in Green and Perry (2008).

Absorbent: Absorbent when present is held in one or more of a fluid (including but not limited to liquid, gas, gasified solid, fluidised solid), a coating on the casing, particulate matter, Non-limiting examples of absorbents are provided in Green and Perry (2008).

Adsorbent: Adsorbent when present is held in one or more of a fluid (including but not limited to liquid, gas, gasified solid, fluidised solid), a coating on the casing, particulate matter. Non-limiting examples of adsorbents are provided in Green and Perry (2008).

Annulus: An aruiulus is the volume contained within a casing, and is used to describe the volume located between two concentric casings, and the volume located within a casing. For example (i) where a reactor is constructed from a single casing, the annulus refers to the volume located inside the casing (ii) where a reactor is constructed from two or more casings which form a series of concentric casings, where each successive concentric casing has either a larger or smaller diameter than its neighbouring casing. The innermost annulus refers to the volume contained within the innermost concentric casing. The outermost annulus refers to the concentric volume enclosed by the outermost casing. The intermediate annuli refer to the volumes located between concentric casings between the innermost annulus and the outermost annulus.

(iii) when the reactor is constructed as a multi-tubular reactor, one or more annuli constructed from either a single casing, or a series of concentric casings, contain two or more casings which are confined to the annulus or annuli. Each of these casings can contain more than one concentric casing and more than one annulus.

Borehole: Any hole extending into the ground which is dug, or drilled, and has a length which is more than five times its diameter is defined as a borehole. The ratio of diameter to length is less than or equal to 0.2, where diameter<length. Length includes the aggregate length of the borehole and all its multi-laterals. Diameter is the average width of the borehole (including its multi-laterals, when present). The diameter may change along the boreholes length. The diameter is measured as the internal diameter of the outer casing. Where the outer casing is constructed from fused rock, or a render (for example concrete coating), the internal diameter is the average diameter of the annulus. The borehole is vertical, or inclined, or horizontal, or a combination thereof. The borehole can be a multi-lateral borehole. Each multi-lateral borehole is vertical, or inclined, or horizontal, or a combination thereof. In a typical embodiment the borehole length is between 0.5 m and 25,000 m. However, the borehole reactor can be constructed to have any suitable length. The length of each multi-lateral is between 0 m and 25,000 m.

The borehole can contain no multi-lateral boreholes, or the borehole can contain one or more multi-lateral boreholes. The term borehole includes extended reach wells.

A borehole reactor is constructed using the outer wall (or casing) of the borehole, or another casing, as the outer wall of the borehole reactor. In some embodiments, the borehole reactor will be inserted as one or more connected segments into the borehole annulus. Borehole reactors inserted into a casing, or liner, will have a diameter to length ratio of less than or equal to 0.2. Length is measured in the direction of fluid flow and diameter is measured perpendicular to the direction of fluid flow.

The reactor can be constructed from two or more boreholes which intersect each other.

Casing: Casing is defined as a tubular structure. Casing can be used to line a borehole. Casing includes all pipes, tubing, conduits, and liners, which can be placed within a borehole. Casing includes coiled tubing, rigid tubing and flexible tubing. Casing can be composite. Casing can have any cross-sectional form, including but not limited to circular, elliptical, square, rectangular, polygonal, triangular, pentagonal, hexagonal, heptagonal, octagonal, cross, star, oval, semi-circular.

The casing is constructed from continuous tubing, or jointed segments, or welded segments, or a combination thereof. Any suitable type of casing joint can be used. These joints include, but are not limited to, screwed flush butt jointed casing (with square or V-profile threads), screwed and socketed butt-jointed casing, butt-jointed welded casing, and flange and spigot jointed casing.

The outer casing can be a thermal fused, or coated rock formation, where the coating, or fusion, is designed to create an impermeable barrier between the borehole annulus and the rock formation. One or more casings can be constructed using expandable tubes or casing. Casings can be insulated or contain insulation between two or more casings.

Casing is constructed from any suitable material. The casing is optionally constructed from a material meeting the standard defined by one or more of the American Petroleum Institute, American Society for Testing and Materials, American National Standards Institute, British Standards Institute, International Organisation for Standardization (ISO) or another standards organisation. Non-limiting examples of different casing types are provided by Lyons and Plisga (2004), Misstear et al. (2006). Non-limiting examples of suitable materials are also provided in Mulder (1996), Green and Perry (2008).

Casing is constructed from one or more of metal, metal alloy, organic material, carbon fibre, thermoplastics, plastics, rock, bricks, glass, concrete, lime, ceramic material, calcium silicates which can be cast or moulded, resins, resin silicate composites, carbon fibre, aramid fibre, graphite fibre, stainless steel fibre, glass fibres, mineral fibres, catalyst, thermoplastics, thermosets, glass reinforced epoxy (GRE), synthetic materials containing carbon or a carbon containing chemical, synthetic materials, or another form of material. Casing can be constructed from composite materials. Different casings within the reactor can have different compositions. The composition of a casing can optionally change along the length of the borehole.

The outer casing is (optionally) cemented into the rock formation. The outer casing can be a rendered coating. Non limiting examples include cement coatings, and fused rock surfaces. The casing can be coated, or impregnated, or a combination thereof with catalyst, or filtrate, or absorbent, or adsorbent, or a combination thereof. The casing can contain material which is coated, or impregnated, or a combination thereof with catalyst, or filtrate, or absorbent, or adsorbent, or a combination thereof.

Permeable casing includes casing which is porous and permeable.

Where a reactant fluid is required to enter the borehole from a rock formation, or enter the rock formation from the borehole, the appropriate section of the cased borehole is either perforated, or slotted, or permeable, or is a bareface completion, or a combination thereof. The outer casing can be constructed over all or part of its length to contain an insulant or a method of adjusting or controlling fluid temperature or a combination thereof. Casings can be composite.

A casing string comprises a length of casing which can be a single piece of casing, or can be constructed by joining two or more pieces of casing. A borehole reactor is constructed from a single casing string, or a casing string containing one or more casing strings within its annulus.

Casing strings contained within a reactor can have a shorter length than the casing string which forms the outer casing of the borehole reactors. In some embodiments casing strings will be hung from the wellhead.

Catalyst: The term catalyst includes any material which can facilitate a chemical reaction, or accelerate a chemical reaction, between one or more components in the reactant fluid to produce a product, or product intermediary. In this specification the terms catalytic and catalyst are used to encompass chemical catalysts. Catalyst, when present, is held in one or more of a fluid (including but not limited to liquid, gas, gasified solid, gasified liquid, fluidised solid), a coating on the casing, a coating on a membrane, impregnated membrane, and particulate matter.

Centralisers: Centralisers include wire brushes, surge blocks, centralising fins, centralisers, stabilizers, packers, expandable packers and other suitable methods, apparatus and equipment which are designed to locate, or fix, or centralise, a casing within the borehole.

Coatings: Casing (including but not limited to pipe, conduits, tubing, liners) and inserts and other structures within the casing can be coated on one or more surfaces. Coatings, or platings, can be thermoplastic fluoropolymer coatings, fluoroplast coatings, metal coatings, or another type of coating or plating. Coatings can include glass reinforced epoxy. Coatings can include or incorporate one or more of catalyst, filtrate, absorbent, adsorbent. Coatings can be constructed from porous and permeable material or permeable material or impermeable material. Coatings can include material which is used to construct porous and permeable membranes or permeable membranes or a combination thereof.

Containers: Containers placed within a reaction zone contain one or more of catalyst, absorbent, adsorbent, filtrate, inert material, reactant, sensors, and other apparatus.

Downstream: Fluid flows within the reactor from an upstream location to a downstream location. A downstream storage area (DSA) is located downstream of an elastic permeable barrier. A downstream screen segment (47) is located downstream of a reaction zone (16). A downstream retaining screen segment (47 is located downstream of a reaction zone (16).

Filtrate: The term filtrate includes any material which can remove one or more components from the reactant fluid by chemically bonding with the filtrate to form a new solid or fluid product. Some materials will have a combination of catalyst, adsorbent, absorbent, and filtrate properties. Filtrate, when present, is held in one or more of a fluid (including but not limited to liquid, gas, gasified solid, gasified liquid, fluidised solid), a coating on the casing, or particulate matter.

Fluid: Any gas, or liquid, or gasified solid, or gasified liquid, or liquefied solid, or a combination thereof. A fluid is defined as a substance that continually deforms or flows in response to an applied shear stress. The definition of fluids includes both supercritical fluids and subcritical fluids. Fluids include one or more of reactants, products, catalyst, filtrate, adsorbent, absorbent and inert material.

Flue gas: Any gas produced from a combustion process, or a carbonisation process, or a chemical process.

Space velocity: m3 (Reactant) hr1 m3 (Catalyst) GHSV = gas hourly space velocity calculated as m3 (Reactant gas, e.g. CON) hr m3 (Catalyst) where CO. C02, or CO, or a combination thereof.

Particulate Bed or Particle Bed: A body of particulate matter which is contained within the annulus or within a container which is within an annulus.

Particulate matter (Particulate Material): The size and nature of the particulate matter placed in the reactor is appropriate to the specific application. Size includes, but is not limited to, particle length, particle diameter, particle sphericity, particle platyness, particle size distribution, modality, skewness, kurtosis, mean, median, quartiles, standard deviation, and other moments. The nature of the particulate matter includes, but is not limited to, composition, shape density, porosity, porosity structure, permeability, permeability structure, pore tortuosity, pore shape and pore distribution, cation exchange capacity and surface area. Individual particles can be porous and permeable. The particulate matter can be constructed from (or contain) catalyst, or absorbent, or adsorbent, or filtrate or a combination thereof. The particulate matter can be coated with one or more catalysts, absorbents, adsorbents, and filtrates. The particulate material can have any size. The particle size selected is appropriate to the application. In some non-limiting embodiments the particulate matter may be constructed as nanoparticles (<1 9 m diameter). In other non-limiting embodiments the particulate matter may be constructed as particles in the range <0.01 to >100mm diameter, while in other non-limiting embodiments the particles may have lengths which may fall in the range <Ito >100 m. The particles can be constructed as monoliths. The particles can be constructed as moulded units (or be placed within moulded units or containers) which are designed to slide into and occupy all or part of an annulus.

Particulate matter includes containers placed in the reactor and monoliths placed in the reactor.

Containers can be used to place solid material containing catalyst, or filtrate, or absorbent, or adsorbent, or inert material, or a combination thereof in the reactor. Particulate matter also includes wire, gauze, fabric, woven material, moulded material, cast material, and any other material which is placed within a reaction zone, or EPB, or is inserted into a reaction zone, or EPB.

Perforated Casing: Perforated casing includes, but is not limited to liners, slotted screens, screens, louvred screens, bridge slot screens, continuous slot screens, slotted liners, perforated casing, perforated liners, permeable casing, permeable screens, permeable liners, wire screen sleeves.

Perforations can optionally be made in a casing after the casing has been inserted into the borehole or positioned within the reactor.

Reaction Zone: A reaction zone contains one or more of catalyst, filtrate, adsorbent, and absorbent or is used for non-catalytic reactions. The reactor contains one or more reaction zones. A reaction zone can be a fluid separation zone, or can incorporate a fluid separation zone.

Reactor Type: Fixed Bed: The reactor is structured as a fixed bed reactor, if one or more casings are coated with, or are impregnated with, or constructed from one or more of catalyst, filtrate, and adsorbent. Fixed bed reactors include, but are not limited to, insert, coated insert, coated wall, wire, carbon nano-tube, nanotube, nano-filament and particulate bed reactors. Coated wall reactors include reactors where an impermeable surface is coated with a membrane. Fixed bed reactors included all forms of membrane reactors. Mulder (1996) and Green and Perry (2008) provide non-limiting examples of membrane materials.

The flow rate through the reactor remains constant under conditions where the fluid flow rate entering the reaction zone equals the fluid flow rate entering the reactor. The fluid flow rate exiting the reaction zone is less than or equal to the combined capacity of the conduits and permeable casing intervals removing fluids from the reactor. The volume of fluid stored upstream of the reaction zone within the reactor remains constant. The volume of fluid stored downstream of the reaction zone within the reactor remains constant.

Reactor Type: Fluidised Bed: The reactor is structured as a fluidised bed reactor when all, or some, of the particles in the reaction zone, are fluid supported while the reactor is in operation. The reactor is constructed as a slurry reactor when the particle bed is held in a liquid and one or more gaseous reactants, or less viscous fluids, or a combination thereof, are bubbled through the reaction zone. The slurry reactor (or slurry bubble reactor) is structured to allow the particle bed to expand during operation, or is structured to prevent the particle bed expanding during operation.

Reactor Type: Oscillating Flow Reactor: The reactor contains an elastic permeable barrier (EPB) which can be a reaction zone. The flow rate through the reactor cyclically varies under conditions where the minimum fluid flow rate entering the EPB is less than the average fluid flow rate entering the reactor. The maximum fluid flow rate exiting the EPB is greater than the combined capacity of the conduits and permeable casing intervals removing fluids from the reactor. The volume of fluid stored upstream of the reaction zone within the reactor cyclically varies with time. The volume of fluid stored downstream of the reaction zone within the reactor cyclically varies with time. The volume of fluid stored upstream of the EPB within the reactor cyclically varies with time. The volume of fluid stored downstream of the EPB within the reactor cyclically varies with time.

The reactor is structured as an oscillating flow reactor when one or more of the inner annulus, intermediate annulus and outer annulus contain a particle bed which is structured as an EPB where; (i) the EPB is constructed from inert material, or catalyst, or filtrate, or absorbent, or adsorbent, or a combination thereof the EPB can contain clay, or be constructed using clay; the EPB is constructed using any suitable particulate material; (ii) the flow rate through the EPB cyclically varies with time from lower flow rates, to higher flow rates, to lower flow rates (or vice versa) and the intrinsic permeability of the EPB cyclically varies with time from lower permeabilities, to higher permeabilities, to lower permeabilities (or vice versa); This invention also allows an oscillating flow reactor to be created by using two boreholes and placing the EPB between the boreholes.

The EPB is located between an upstream storage area and a downstream storage area. The annular volume within the reactor located upstream of the EPB is defined here as the upstream storage area (USA). The annular volume within the reactor located downstream of the EPB is defined here as the downstream storage area (DSA).

The intrinsic permeability of the EPB changes as the driving force across the EPB changes. The driving force is defined as [(pressure in USA) minus (pressure in DSA) minus (pressure losses within the EPB)J. The change in intrinsic permeability may include one or more changes in permeability by one or more orders of magnitude. The reaction zone (16) is located in the USA, or DSA, or EPB, or a combination thereof.

Fluid is delivered to the USA through a conduit (or from a rock formation, or a combination thereof), at a pressure PA. The fluid pressure within the USA is P8. The pressure in the DSA is Pc and the pressure in the discharge conduit (or rock formation receiving the fluid) is PD. At any moment in time PA> P8, PB> Pc, subject to PA>PD. P8 cyclically varies with time. As P8 increases, P decreases. As P8 decreases, Pc increases. Flow rate Q (m3 m2 s5 = k P; k intrinsic permeability (m3 m2 s1 Pa'); P = driving force (Pa).

Each oscillating flow cycle commences with the EPB operating with a low intrinsic permeability (e.g. diffusion flow) and PA> B. The flow rate, QA, into the USA, is greater than the flow rate, QB, through the EPB. This results in PB increasing as the volume of fluid stored in the USA increases. At a critical pressure difference between PB and Pc, the intrinsic permeability through the EPB increases (for example the switch from diffusion flow to viscous flow). This results in Qn increasing. The switch from a dominant flow in a lower permeability flow regime (for example diffusion flow) to a dominant flow in a higher permeability flow regime (for example viscous flow in unexpanded porosity) may be localised.

Over time the entire EPB may switch from the lower permeability flow regime to a higher permeability flow regime. At this point, if QB> QA, the volume of fluid in the USA will decrease and PB decrease. At a critical pressure difference between P8 and P, the flow regime will change from the higher permeability flow regime to a lower permeability flow regime and Qe <QA. At this point P8 will start to increase. If, however, when flow is switched from the lower permeability flow regime to the higher permeability flow regime, QB <QA, then B will continue to increase until the porosity in the EPB starts to expand, or k switches to a higher intrinsic permeability flow regime, or Q QA. This porosity expansion will increase the intrinsic permeability and result in QB increasing, When the porosity expands (and intrinsic permeability) increases sufficiently such that QB> QA, (i) the volume of fluid in the USA will decrease (and the volume of fluid in the DSA increase) and (ii) P decreases. At a critical pressure difference between PB and P, Q <QA, and PB will start to increase as the volume of fluid in the USA increases.

Zones of high permeability (macropores, flow channels, fractures, natural pipes) may develop within the EPB. They will propagate from the USA toward the DSA and will be accompanied by the development of a zone of viscous flow in unexpanded porosity (or expanded porosity) around the macropores. During this phase QB <QA, and B increases as the volume of fluid in the USA increases.

At a critical point in time the propagating macropore zone intersects the USA. At this point either: (i) Q> QA, and the volume of fluid in the USA decreases. When P8 decreases below a critical pressure difference between PB and Pc, the macropore network/high intrinsic permeability collapses and Qs <QA; or (ii) QB <QA and P8 continues to increase until the EPB fluidises or sufficient macropores/high intrinsic permeability have developed to allow QB > QA. At this point P8 decreases. When PB decreases below a critical pressure difference between P and Pc' the flow regime switches to a type of flow with a lower intrinsic permeability and QB <QA. At this point P8 starts to increase as the volume of fluid in the USA increases.

When the reactor is constructed as an oscillating flow reactor and used for processing gases, volume adjustments in the USA and DSA result from increases or decreases in fluid pressure within the USA and DSA. When the reactor is constructed as an oscillating flow reactor and used for processing liquids, volume adjustments in the USA and DSA require the presence of a displaceable fluid (e.g. air, inert gas, gas, liquid) in the USA and DSA. Conduits ((1 1), e.g. Figure le) can be inserted into one or more of the USA and DSA from the wellhead to allow a displaceable fluid to be placed within the reactor. All, or part, or none, of the displaceable storage volume (and fluid displacement) associated with the DSA and USA may be located in one or more storage vessels located outside of the borehole reactor.

Reactor Type: Oscillalory Flow or Turbulent Flow Reactor: The reactor is constructed as an oscillatory flow reactor or turbulent flow reactor when protrusions or flow restrictors are placed within the reactor in order to increase turbulence or alter the relative velocity of fluids flowing within different parts of the reactor.

Reactor Type: Packed Bed: the reactor is structured as a packed bed reactor if one or more of the inner annulus, intermediate annulus and outer annulus contain catalyst, or filtrate, or adsorbent, or absorbent, or a combination thereof and: (I) the porosity of the particles in the reaction zone does not vary as a function of the flow rate through the borehole reactor; (ii) the intrinsic permeability of the particles in the reaction zone does not vary as a function of the flow rate through the borehole reactor; A mechanism or apparatus may be included to prevent the porosity between the particles expanding.

Reactor Type: Particulate Bed: A particulate bed reactor (or expanding bed reactor) is a form of fixed bed reactor. The reaction zone includes one or more of particles, wire, coated inserts, foam monoliths or some other particulate form. The particles can be present in one or more moulded permeable (or porous and permeable) blocks, or containers, which fill, or partially fill, the annular volume: 1. the porosity of the particulate material, may vary as a function of the flow rate through the borehole reactor; 2. the intrinsic permeability of the particulate material, may vary as a function of the flow rate through the borehole reactor.

Reactor Type: Pulsed Flow Reactor: The flow rate through the reactor is cyclically varied under conditions where the fluid flow rate entering the reaction zone equals the fluid flow rate entering the reactor. The fluid flow rate exiting the reaction zone is less than or equal to the combined capacity of the conduits and permeable casing intervals removing fluids from the reactor. The volume of fluid stored upstream of the reaction zone within the reactor remains constant. The volume of fluid stored downstream of the reaction zone within the reactor remains constant. The volume of fluid stored within the reactor remains constant. A pulsed flow reactor can be structured as one or more of a fixed bed reactor, fluidised bed reactor, membrane reactor, packed bed reactor, particulate bed reactor (expanding bed reactor).

Rock: The term rock includes igneous rocks, metamorphic rocks, sedimentary rocks, pyroclastic rocks, artificial rocks, sediments, soils, construction fill and artificially made ground.

Screen: Screens include retaining screens. Retaining screens are designed to prevent a fluid, or a particle, or an entrained particle, or a combination thereof, leaving a reaction zone. Retaining screens are designed to allow reactants, or products, or a combination thereof. to pass through them. Screens are designed to allow fluids and optionally may allow entrained particles to flow through the screen.

Synthesis gas: A gas containing CO and H2. It can contain one or more of H20, C02, CH4, CXHYOZ, N2 and other chemicals.

Upstream: Fluid flows within the reactor from an upstream location to a downstream location, A upstream storage area (USA) is located upstream of an elastic permeable barrier. A upstream screen segment (47) is located upstream of a reaction zone (16). A upstream retaining screen segment (47 is located upstream of a reaction zone (16).

Valve: Method, or apparatus, or a combination thereof, designed to control, or exercise control, over the flow rate in a conduit. Non-limiting examples of valves are provided in Green and Perry (2008). A valve can also include a compressor, pump, blower, exhauster, weir, sluice, and adjustable flow restrictor of any kind. A valve is constructed to be able to (i) adjust flow rates through a conduit and has the ability to terminate flow through a conduit, or (ii) adjust flow rates through a conduit, without having the ability to terminate flow through a conduit, or (iii) terminate flow through a conduit without having the ability to adjust flow rates through a conduit. Valves can be placed at any suitable location within the reactor. A reactor can be constructed without any valves being present.

Wellhead: Seal at the upper surface of the borehole reactor. One or more conduits discharge fluids into the reactor, or remove fluids from the reactor, or a combination thereof, through the wellhead. The welihead optionally provides a connection for a blowout preventer or another method of pressure control. The wellhead optionally provides support for the casing strings. One or more casing strings can be suspended from the wellhead. The welthead provides a top seal for the different casing strings. The wellhead allows access to all or some of the annuli between the different casing strings. The welihead may optionally be designed and constructed in accordance with ISO 10423 wellhead and christmas tree equipment, or API 6a Specification for welihead and christmas tree equipment, or the requirements for a water well (e.g. Misstear et al,, 2006), or may optionally be constructed in accordance with another

specification.

BRIEF DESCRIPTION OF FIGURES

1. Figure 1: General borehole reactor structures constructed within a borehole. The reactor structures illustrated in Figures 1 and 2 contain one or more Reaction Zones (16). These are placed at appropriate locations within the reactor.

a. Figure Ia: a borehole reactor with a single casing; b. Figure Ib: a borehole reactor with an outer casing and an inner casing; C. Figure Ic: a borehole reactor with an outer casing, intermediate casing and an inner casing; d. Figure Id: general structure of the borehole reactor when it uses a rock formation as anEPB; e. Figure 1 e: schematic cross sections through a borehole reactor constructed from a single casing, two casings and three casings; 2. Figure 2: General borehole reactor structures when the reactor is constructed as a sealed unit: a. Figure 2a: single casing, sealed unit, constructed as a U-tube and placed within a borehole; b. Figure 2b: dual casing, sealed unit, borehole reactor placed within a borehole; C. Figure 2c: triple casing, sealed unit, borehole reactor placed within a borehole; d. Figure 2d: single casing sealed unit constructed with an internal divider and placed within a borehole; e. Figure 2e: single casing sealed unit placed within a borehole; 3. Figure 3: Illustrative boreholes structures used to induce turbulent flow or pressure losses a. Figure 3a: protrusions used to induce turbulent flow and equipment placed inside a reactor; b. Figure 3b: protrusions designed to create pressure losses (i.e. vary flow rates) within the reactor; 4. Figure 4: Example of a pig or mandrel expanding a casing 5. Figure 5: Examples of outer casing strings constructed using conventional tubing, and constructed using a mixture of conventional tubing and expandable tubing.

6. Figure 6: Example of a borehole reactor containing two horizontal sections, where each horizontal section contains a reaction zone 7. Figure 7: Examples of reaction zones where reactants and products flow from one annulus to another.

8. Figure 8: Membrane unit within a borehole reactor: The membrane unit is structured as a membrane reactor, or a membrane separator, or a combination thereof. Each membrane unit is constructed from a permeable section (of casing). Membrane units can be placed at any suitable location, or locations, within the reactor. In some embodiments the reactants are confined to an annulus (one or more of(5, 7, 8)). In this instance the membrane unit is constructed using a membrane coating on the inner surface, or outer surface of an impermeable section (of casing), or by placing a membrane in the annulus (one or more of(5, 7, 8)).

a. Figure 8a: Example longitudinal cross section. The membrane unit is constructed using a permeable section. This membrane unit allows fluids to pass through the casing wall. The membrane coating can be on the outside, or inside or a combination thereof, of the membrane unit; b. Figure 8b: Example longitudinal cross section with optional collars, stabilisers or centralisers.

C. Figure 8c: Example longitudinal cross section with an optional protective frame or structure.

d. Figure 8d: Example cross section perpendicular to the direction of fluid flow showing optional divisions or support structures within the annulus of the membrane unit.

e. Figure 8e: Example optional longitudinal cross section showing a sealed base to the membrane unit, and an optional central division within the annulus, which allows fluids to travel in opposite directions and a perforated zone, or gap in the division, which allows fluid to flow from one part of the annulus to the other.

1. Figure 8f: Example longitudinal cross section where the membranes are contained within the annulus of the membrane unit, g. Figure 8g: Example longitudinal cross section showing the membrane unit structured as a forced flow catalytic membrane reactor.

h. Figure 8h: Example longitudinal cross section showing fluid in an adjoining annulus forced to flow through the membrane and into the annulus of the membrane unit.

9. Figure 9: Example Reaction Zone Units: The drawings show the presence of optional screens (47) or retaining screens (47). Each reactor can contain more than one reaction zone unit.

Reaction units are placed at any suitable location or locations within the reactor.

a. Figure 9a: Flow through reaction zone unit constructed using an impermeable segment b. Figure 9b: Flow through reaction zone placed within a membrane unit. Two groups of fluid are mixed within the reaction zone.

C. Figure 9c: Flow through reaction zone placed within a permeable segment. Two groups of fluid are mixed within the reaction zone.

d. Figure 9d: Terminal reaction zone placed within a permeable segment containing a seal (45) or a basal seal ((10) not illustrated). Fluid enters the reaction zone through the casing wall and leaves through the annulus (or vice versa). The terminal reaction zone can be constructed using a membrane unit.

e. Figure 9e: Force flow reaction zone placed in a permeable segment containing two seals. Fluid enters the reaction zone through the permeable casing. Fluid leaves the reaction zone through the permeable casing. The permeable casing can be constructed as a membrane.

10. Figure 10: Casing segments used to construct a borehole reactor. The reactor is constructed by combining casing segments.

a. Impermeable Segment b. Permeable Segment C. Seal segment containing a seal within the annulus and both optional impermeable casing and optional permeable casing d. Terminal seal segment where the seal is located at one end of the casing. The segment contains both optional impermeable casing and optional permeable casing e. Screen segment containing a screen within the annulus and both optional impermeable casing and optional permeable casing. A retaining screen segment replaces the screen with a retaining screen.

1. Impermeable segment containing one or more of a reaction zone container, or monolith, or a disc, or a seal, or a valve, or a screen, or a retaining screen.

g. Impermeable segment containing one or more of a reaction zone container, or monolith, or a disc, or a seal, or a valve, or a screen, or a retaining screen.

h. Impermeable segment containing one or more of a reaction zone container, or monolith, or a disc, or a seal, or a valve, or a screen, or a retaining screen.

i. Impermeable segment containing one or more of a reaction zone container, or monolith, or a disc, or a seal, or a valve, or a screen, or a retaining screen.

j. Example seal segments, retaining screen segments, and screen segments; the seal segment can be constructed using a valve.

k. Example cross sections through a segment showing optional screens constructed using bars or rods 11. Figure 11: Construction of reactors using standard casing segment units. The non-limiting Figures all illustrate the basal section of the reactor and exclude the wellhead. The reactor may contain other reaction zones between the wellhead and the basal section of the reactor. The non-limiting figures all illustrate the base of the inner casing (6) and base of the intermediate casing (9) resting on the basal seal (10) of the outer casing (4). Each of the inner casing (6) and intermediate casing (9) will have their own basal seal (10) or seal (45). In some embodiments one or more of the inner casing (6) and intermediate casing (9) will have no seal (45), or no basal seal (10). In some embodiments the base of one or more of the inner casing (6) and intermediate casing (9) will be suspended above the basal seal (10) of the outer casing string (4).

a. Single fluid processing reactor where the product leaves the reactor through the wellhead and the reactant enters the reactor through the outer casing b. Single fluid processing reactor where the reactant enters the reactor through the wellhead and the product is discharged through the outer casing C. Single fluid processing reactor where the reactant and product fluids leave the reactor through the wellhead. The reaction zone is in the inner annulus and fluid enters the reactor through the outer annulus.

d. Single fluid processing reactor where the reactant and product fluids leave the reactor through the welihead. The reaction zone is in the inner annulus and fluid enters the reactor through the inner annulus.

e. Dual fluid processing reactor where a reactant fluid enters the reactor through the welihead and the product fluid leaves the reactor through the welihead and a reactant enters the reactor through the outer casing. The reaction zone is in the inner annulus.

f. Dual fluid processing reactor where the reactant fluids enter the reactor through the welihead and a product fluid leaves the reactor through the outer casing g. Dual fluid processing reactor where the reactant fluids enters the reactor through the welihead and the product fluid leaves the reactor through the welihead and a reactant enters the reactor through the outer casing. The reaction zone is in the outer annulus.

h. Dual fluid processing reactor where the reactant fluids enter the reactor through the wellhead and a product fluid leaves the reactor through the wellhead. The reaction zone is placed in the inner annulus.

i. Dual fluid processing reactor where the reactant fluids enter the reactor through the welihead and a product fluid leaves the reactor through the welihead. The reaction zone is placed in the outer annulus.

j. Dual fluid processing reactor where the reactant fluids enter the reactor through the welihead and a product fluid leaves the reactor through the welihead. The reaction zone is placed in the intermediate annulus.

12. Figure 12: Reaction Zone Unit Construction. The reaction zones are constructed from impermeable segments, or permeable segments, or a combination thereof. Figures 12a to 121 show non limiting examples of reaction zones constructed using impermeable segments. These reaction zones are located within a reactor.

a. Coated Reactor: Coating (containing one or more of catalyst, filtrate, adsorbent, absorbent) placed on the outside of an impermeable segment.

b. Coated Reactor: Coating (containing one or more of catalyst, filtrate, adsorbent, absorbent) placed on the inside of an impermeable segment.

C. Wire Reactor: wire screens or units placed within an impermeable segment. The wire screens can optionally be attached to an electrical system which is designed to regulate their temperature, or create an electomagnetic field or expose the fluid within the annulus to an electric current. The reactor can be created by combining screen segments.

d. Reactor constructed using monoliths, or discs, or screens, or containers, or a combination thereof, placed within an impermeable segment.

e. Packed Bed Reactor placed within an impermeable segment.

f. Packed Bed Reactor, or fixed bed reactor, or membrane reactor, placed within an impermeable segment containing a conduit (56) which is design to assist the flow of products from the reaction zone.

g. Fixed bed, or particulate bed, or expanding bed, or pulsed flow, or oscillating flow, or fluidised bed, or slurry reactor placed within an impermeable segment.

h. Reaction zone is contained within a series of linked containers placed within the annulus of an impermeable segment.

i. Non-limiting cross sections through a borehole reactor which is constructed as a multi-tubular reactor.

(i) Constructed as an outer casing. A number of inner casing strings containing reaction zones are placed in the inner annulus.

(ii) Constructed as an outer casing and an inner casing with a number of casing strings containing reaction zones placed in the outer annulus (iii) Constructed as an outer casing and an inner casing with a number of casing strings containing reaction zones placed in the inner annulus 13. Figure 13: Example construction as a high pressure reverse osmosis or forward osmosis fluid separator designed to remove freshwater from saline water (e.g. sea water) a. Reactor construction where the reactor has an outer casing which acts as a protective screen, an intermediate casing containing the reverse osmosis (or forward osmosis) membrane and an inner casing which includes a filter and is used to suck or pump fresh water out of the reactor b. Examples showing example reactors. In example (65) the base of the reactor unit may typically extend from less than 1 m below the seabed to more than 20 km below the seabed. Increasing the depth of the borehole reactor, will increase the maximum pressure differential that can be generated across a reverse osmosis (or forward osmosis) membrane placed towards the base of the reactor.

DESCRIPTION OF THE INVENTION

The invention is a borehole reactor which is constructed within a borehole, or is inserted into a borehole, or is placed into water, or is placed in air, or is placed below ground, or a combination thereof. The reactor is constructed outside the borehole, or inside the borehole, or a combination thereof. The reactor is constructed from continuous lengths of casing, or coiled tubing, or separate lengths of casing, or a combination thereof. The reactor is constructed from one or more casing segments (selected from impermeable segments, permeable segments, retaining screen segments, screen segments, seal segments, basal seal segments). Each reactor contains one or more reaction zone units and may include one or more membrane units. A reaction zone unit can incorporate a membrane unit.

The reaction zone units and membrane units are constructed using one or more casing segments selected from impermeable segments, permeable segments, retaining screen segments, screen segments, seal segments, basal seal segments units.

Reactor Modular Construction Each reactor is constructed by combining standard casing segments, or customised casing segments, or a combination thereof. Six types of casing segment are used to construct a reactor. These standard casing segments are termed impermeable segments, permeable segments, seal segments, basal seal segments, retaining screen segments and screen segments. These segments are used to construct reaction zones (termed reaction zone units) within the reactor. They are used to construct sections of the reactor which operate as membrane separators or as membrane reactors (termed membrane units). The top seal of the reactor is formed using a wellhead (1).

Reactor Dimensions Each reactor has a ratio of internal diameter to length of less than or equal to 0.2. For example a reactor m long must have an internal diameter of less than or equal to I m. Diameter is less than length and is measured as the average internal diameter of the outer casing. Internal diameter is measured as the average internal diameter of the outermost casing. Reactors can, for example, be constructed to have a ratio of diameter to length of <0.1, or <0.03, or <0.003, or <0.0003, or <0.00003, or <0.000003. Non limiting examples include:- 1. A reactor 10 m long with an average outer casing internal diameter of 0.1 m. The ratio of diameter to length 0.1/10 0.01 2. A reactor 100 m long with an average outer casing internal diameter of 0.3 m. The ratio of diameter to length = 0.3/100 0.003 3. A reactor 1000 m long with an average outer casing internal diameter of 0.2 m. The ratio of diameter to length 0.2/1000 = 0.0002 4. A reactor 5000 m long with an average outer casing internal diameter of 0.2 m. The ratio of diameter to length 0.2/5000 = 0.00004 5. A reactor 25000 m long with an average outer casing internal diameter of 0.2 m. The ratio of diameter to length 0.2/25000 0.000008 The reactor is a casing string which is constructed with an outer casing, a wellhead, and a basal seal.

The basal seal can be a seal segment, or a basal seal segment; the reactor can be constructed to contain more than one casing string within the outer casing. The wellhead forms the top seal for the reactor.

Reactor Base In the preferred embodiment, each reactor has a sealed base, which is constructed as a seal segment, or basal segment, or an impermeable segment (or permeable segment, or retaining screen segment or screen segment) containing one or more of an expandable packer, a seal, a packer, a valve, a cement plug, a plug/seal (constructed from any suitable impermeable material or apparatus), an impermeable rock formation. The reactor can be constructed with one or more segments located below the seal. In this specification a sealed base to a casing string (basal seal, or basal seal segment) is given the number notation (10). A seal which is placed within a casing segment, though not at the base of the segment (seal segment) is given the number notation (45).

In some applications it is desirable to allow a fluid to enter or leave the reactor through its base. In these applications the base is either not sealed, or is sealed, with a retaining screen segment, or a screen segment which allows fluids to enter or leave the reactor.

Top of the Reactor Each reactor has a sealed top (or wellhead (1)) which allows one or more fluids to enter or leave the reactor through one or more conduits.

Wellizead Location The wellhead (1) is positioned on, or above, the ground surface (2), or below the ground surface, or on the seabed, or on the lake bed, or in water, or partially in water, or on a structure, or on a platform, or on a ship, or a tension leg platform, or on floating facility, or on a mobile facility, or on a tension leg facility, or a combination thereof. The outermost casing (4) is attached to the wellhead, and the wellhead forms the top seal for the reactor.

Reactor Orientation The reactor has one or more of a horizontal, or vertical, or inclined orientation.

Reactants and Products The reactor is constructed to process a single fluid, or two or more fluids. The reactants enter the reactor through the wellhead, or from the rock formation, or from a water body, or from the atmosphere, or a combination thereof. The products leave the reactor through the wellhead, or through the rock formation, or through a water body, or through the atmosphere, or a combination thereof.

When the reactor receives fluid from a rock formation (or water body, or the atmosphere), or discharges fluid from the reactor into the rock formation (or water body, or the atmosphere), or a combination thereof, one or more sections of the outer casing are constructed using one or more permeable segments. A pemeable segment includes one or more of perforated intervals, slotted intervals, casing gaps, porous and permeable intervals, permeable intervals. In some embodiments where the basal seal segment is replaced by a retaining screen segment, or a screen segment, or a seal, or where the seal is omitted, fluids will be able to enter or leave the reactor through the annulus. This situation is not limited to, but can include some embodiments which are designed to desalinate water, or treat water, or a combination thereof.

Movement of Fluids Within the Reactor When the reactor contains more than one annulus there is a requirement to move fluid from one annulus to another. These intervals are designed to allow fluids to enter into a reaction zone, or change flow direction within a reactor, or assist with fluid mixing, or assist with fluid separation, or change the location of flowing fluids within a reactor (e.g. from an inner annulus to an outer arinulus).

The reactor is constructed to allow fluids to flow from one annulus to another, by either:- 1. suspending the separating casing or liner from the wellhead, thereby creating a gap at the base of the separating casing. This gap allows fluid to flow from one annulus to another, or 2. constructing one or more segments of the separating casing from one or more permeable segments. These permeable segments allow fluid to flow from one annulus to another, or 3. a combination thereof.

The fluid flow directions identified (arrowed) in Figures 1 and 2 are illustrative and all possible fluid flow directional permutations are incorporated. In some operational situations it may be desirable to mix two or more reactants within an annular area by delivering them to the mixing point using tubing or piping contained within an annulus.

Reaction Zone The reactor undertakes, within a reaction zone (16), one or more of catalytic reactions, noncatalytic reactions, fluid adsorption/absorption, filtration and fluid separation. The reactor contains one or more reaction zones. The reactors are used for batch processing of fluids, or for the continuous flow processing of fluids. Reaction zones (when more than one reaction zone is present) are arranged in series, or in parallel, or a combination thereof.

Reaction Zone Structure The reactor contains one or more reaction zones (16), Each reaction zone is operated as a fixed bed, or a fluidised bed, or a packed bed, or an expanding bed, or a particulate bed, or a membrane reactor, or a coated wall, or oscillating flow, or pulsed flow reactor, or a membrane separator, or an EPB, or a combination thereof.

Different reactant fluid streams are mixed in an annulus before entering the reaction zone, or are mixed before they enter the reactor, or after one or more fluids has passed through a reaction zone, or within the reaction zone, or a combination thereof. When the reactant fluid groupings are mixed within the reaction zone a plurality of fluid inlets supply one reactant directly into the reaction zone at an oblique angle to the direction of fluid flow in the annulus. The other reactant enters the reaction zone from a location within the annulus, which is upstream of the reaction zone, or enters the reaction zone from the adjoining annuli through a plurality of fluid inlets set at an oblique angle to the direction of fluid flow in the recipient annulus. The fluid inlets can be of any size (e.g. from <ItT9 m to >l0 m), and can have any size distribution, shape, form and angle.

Each fluid group contains one or more reactants. Each fluid group can contain one or more of reactants, catalyst, filtrate and absorbent/adsorbent. Each fluid group can include inert fluids.

One or more packers, or valves, or other apparatus can be used to control, or direct, or restrict fluid flows in one or more annuli. Centralisers can be used to position casings. Dividers can be used to divide annuli, to isolate different fluid streams within an annulus, or to allow an unused part of a reactant fluid to be returned to the wellhead, or to create a recycle ioop within the reactor, or a combination thereof. One or more of packers, expanded tubing, and valves can be used to create blockages within annuli in order to confine reactants, or products, to specific annuli, or direct fluid from one annuli to another.

The invention incorporates four types of reaction zone: (i) Reaction zones where the catalyst (or filtrate, or absorbent/adsorbent, or a combination thereof) is placed in the reactor and left in the reaction zone for its entire operating life.

(ii) Reaction zones where the catalyst (or filtrate, or absorbentiadsorbent, or a combination thereof) is placed in the reaction zone and is periodically removed and replaced. Non limiting examples which allow replacement of the catalyst include: a. increasing the flow rate (or fluid density) through the borehole to result in the fluidisation of the catalyst (or filtrate, or absorbent/adsorbent, or a combination thereof) and its removal by a circulating fluid. This type of reaction zone does not have an upper retaining screen unit, or has a retaining screen unit which can be removed or opened or otherwise altered to allow particulate matter to be removed by a circulating fluid, b. removing the casing and segments containing the reaction zone and replacing the reaction zone C. the placement of the reaction zone within removable segments of tubing, which can be periodically removed and replaced, d. the placement of the reaction zone in one or more of baskets, containers, sleeves, removable units, another removable form. They are structured to allow removal and replacement when necessary.

(iii) Reaction zones where the catalyst (or filtrate, or absorbent/adsorbent, or a combination thereof) is continuously placed in the reactor and is continuously removed. In this type of operation the catalyst (filtrate, or absorbent, or a combination thereof) is added as a fluid with the reactant. A non-limiting example application is the production of biodiesel.

(iv) Reaction zones where the reactor is able to produce a product without catalysis. Non limiting examples of process which can be undertaken within the borehole reactor include the production of biodiesel at pressures of>5 MPa using the Saka Process or Saka Dadan Process (e.g. Saka and Minami, 2006), the direct conversion of methane and oxygen to methanol (e.g. US 4618732). The latter process requires the reactor walls to be coated with a material which is designed to be inert (e.g. coated with polytetrafluoroethylene).

When the reaction zone includes a membrane, fluids can be periodically added to clean, or reactivate, a fouled membrane.

The reactor can be constructed to include a method and apparatus which is designed to: 1. add or remove, or add and remove one or more of catalyst, filtrate, and absorbent/adsorbent; 2. add or remove, or add and remove one or more of casing, liners, tubing centralisers, packers and other apparatus; 3. activate, or clean, or regenerate, or a combination thereof, a catalyst, or filtrate or absorbent/adsorbent, membrane, or a combination thereof. Activation may require a reducing gas (e.g. a gas containing H2, or NH4 or CO) to be passed over the catalyst (or filtrate, or absorbent/adsorbent, or a combination thereof), or the catalyst (or filtrate, or absorbent, or adsorbent, or a combination thereof) to be periodically agitated (for example fluidised).

REACTOR CONSTRUCTION NOTATION ON THE FIGURES

The Figures in this specification provide non-limiting examples of the reactor constructed using a single casing string, two casing strings, or three casing strings in order to illustrate the basic principles of reactor design using the various modular casing segments. These principals can be applied to the construction of more complex borehole reactor designs containing one or more casing strings. They can also be applied to the construction of a reactor using more than three casing strings. In some embodiments the number of casing strings present in a borehole reactor will vary along its length.

Figures I and 2 illustrate the basic layout of the casing strings in a simple reactor containing one, two or three casing strings. I wellhead; 2 = ground surface; 3 borehole. The borehole can be a cased hole; 4 = Outer casing of the reactor. The outer casing can be a pre-existing casing within a borehole; 5 = Innermost annulus within a borehole; 6 = Innermost casing in the reactor, when the reactor is constructed from more than one casing; 7 Outermost annulus in the reactor, when the reactor is constructed from more than one casing; 8 Intermediate annulus in the reactor, when the reactor is constructed from more than two casings. The reactor can contain more than one intermediate annulus; 9 = Intermediate casing in the reactor, when the reactor is constructed from more than two casings, each additional casing is termed an intermediate casing. The reactor can contain more than one intermediate casing. Each additional casing subdivides an annulus into two concentric annuli as illustrated in Figure le (for a cross section which is perpendicular to the reactors length). Figure le provides cross sections through a reactor constructed using one casing, two casings, and three casings; 10 basal seal segment.

This provides a seal for the reactor. In some embodiments the basal seal segment may be replaced by a seal segment, or a retaining screen segment, or a screen segment, or a seal.

Figures la and 2e illustrate the simplest structural arrangement for a borehole reactor, which is either formed from the casing lining a borehole, or formed by inserting the reactor into the borehole.

Multi-tubular Reactor In some embodiments, the reactor will be constructed as a multi-tubular reactor where a number of smaller diameter casing strings (which may optionally have a similar, or the same diameters) are placed within the annulus of a larger diameter casing string. These smaller diameter casing strings allow the reactor to be constructed to operate with a number of reaction zones operating in parallel (e.g. Figure 12i).

Reactor Construcled Using Two Boreholes (or groups of borehole reactors) A borehole reactor can be constructed (e.g. Figure Id) to use a rock formation (13) located between two borehole reactors as an EPB (EPB (12)). The upstream borehole contains the upstream storage area (14). The downstream borehole contains the downstream storage area (15). The reaction zone (16) is placed in one or more of the EPB (12), upstream storage area (14), and downstream storage area (15).

1. Reactants enter the upstream borehole through the wellhead 2. Reactants, or products, or a combination thereof are discharged into the rock formation (13) which forms the EPB (12) from the upstream borehole.

3. Products, or reactants, or a combination thereof, flow into the downstream borehole from the rock formation (13) which forms the EPB (12) 4. Products (and residual reactants) are recovered through the wellhead from the downstream borehole.

Reactor Inserted into a borehole Figure 2 illustrates the reactor constructed as a sealed unit which can be placed in a borehole, or water body, or in the ground, or the air, or a combination thereof. The annular volume (17) between the outer casing (4) of the sealed unit and the outer margin of the borehole (3) may contain a fluid, or a solid material, or a combination thereof. The material (17) can be cement. The material (17) can be an insulant. The material (17) can be a circulating fluid (which can be heated (or cooled)) and can be designed to provide an external temperature control for the sealed unit, In some embodiments the outermost casing (4) will be placed within a casing (e.g. 3) in order to assist in controlling the temperatures within the reactor, or to recover heat from the reactor or to add heat to the reactants.

Conduits Each annulus can optionally contain one or more conduits (II) which allow fluids to be added to (or removed from) a deeper location, or are used to protect control lines (Or electricity supply lines, or optic cables, or another form of energy supply), or have another purpose (e.g. Figure 1 e).

Partitions Figure 2d illustrates an example where the innermost annulus (5) contains a longitudinal partition (18).

This partition (18) subdivides the annulus into two isolated conduits. The partition (18) is constructed to allow fluid to pass from one compartment to the other through a gap in the partition, or a porous and permeable interval, or a permeable interval, or a perforated interval, or a slotted interval, or a combination thereof(19). An annulus can be constructed to have more than one partition (18) and can be constructed to have more than one location (19) where fluids pass from one partitioned conduit to another partitioned conduit.

Packers, Valves and Conduits Packers, expandable packers, swellable packers, valves, expanded tubing, or another method, or apparatus can be used to restrict, or contain flow, within an annulus. They can be used to redirect fluid flow from one annulus to another. The number of annuli present within a reactor, or used by flowing fluids, can change along the length of the reactor. The conduits, which deliver, or remove, a fluid through the welihead or a rock formation can extend into the annulus. Each conduit located within the borehole reactor can contain one or more valves. Instruments designed to measure temperature, pressure, flow rate, fluid composition, or another parameter within the borehole reactor can be placed at any suitable location within the reactor.

Turbidity and Apparatus Apparatus can be placed within the reactor to increase turbidity (and mixing). This apparatus (Figure 3a) can be in the form of one or more wireline ultrasound generators (20) or microwave generators (20), or electromagnets (20), or lasers (20), or magnets (20), or electrical sources (20), or protrusions (of any form) on the side of the casing (21), or a wireline apparatus (or tube insert) designed to increase turbidity, or a combination thereof. The protrusions can be permanent or temporary. The protrusions (21) can be fixed or adjustable. In some embodiments, it is desirable to accelerate and deaccelerate the fluid travelling through the reactor. This can be achieved (Figure 3b) by placing flow restrictions (22), or apparatus (23) within the annulus. The flow restrictions (22, 23) can be fixed or adjustable. In some embodiments this apparatus will be constructed as a screen segment.

Operating Conditions When more than one borehole reactor is present in a process train, the borehole reactors are arranged in series, or in parallel, or in a combination thereof. Borehole reactors are constructed to operate at a constant (or variable) pressure within the reaction zone. The operating pressure can vary within the borehole. Borehole reactors can be constructed to undertake reactions which require a pressure within the reaction zone of between <001 MPa and I GPa. The pressure within the reactor is higher than, or less than, or equal to the pressure exerted by the pore fluids in the surrounding rock formation. The flowline pressure in the borehole reactor is greater than, or less than, or equal to the pressure exerted by the pore fluids on the borehole reactor. Borehole reactors are constructed to operate over a higher pressure range than a conventional reactor, or the same pressure range as a conventional reactor, or a lower pressure range than a conventional reactor, or a combination thereof. This allows the reactor to extend the operating range of some catalysts. The operating range of GB087 17567.1 is specifically extended to 1 GPa when used in conjunction with a borehole reactor. The borehole reactor can extend the operating pressure range of some fluid separation membranes. This can allow fluid separation processes to be undertaken in the borehole reactor, with a higher pressure differential across a membrane than the pressure differential in a surface based fluid separation apparatus.

Borehole reactors are constructed to operate at a constant (or variable) temperature within the reaction zone. The operating temperature can vary within the borehole. Borehole reactors are constructed to undertake reactions which require a temperature within the reaction zone of between -100°C and 1400° C. Borehole reactors can be constructed to use horizontal laterals, or horizontal sections, or a combination thereof, to create isothermal conditions, or near isothermal conditions, within the reaction zone. Borehole reactors can be constructed to use horizontal laterals, or horizontal sections, or a combination thereof, to facilitate the operation of reaction zones placed in series where each reaction zone operates under different temperature conditions. Borehole reactors can be constructed such that different isothermal conditions, or different temperature conditions, are present in different parts of the reactor, in order to facilitate different reactions in different parts of the reactor, or to assist with heating, or cooling, a fluid within the reactor.

Counterfiows of fluids in adjoining annuli can be used to allow the reactor to act as a balanced flue where heat is exchanged between the fluids in adjoining annuli. The fluids in the outermost annulus will also exchange heat with the fluids in the environment surrounding the reactor.

Flexibility Unlike a conventional reactor a borehole reactor can be assembled on site and can be constructed using standard (or customised) casing segments. This can allow a borehole reactor to be constructed more quickly and at lower cost than a conventional reactor with a similar capacity. The high structural strength of casing can allow the reactor to be used for higher pressure operations than many conventional reactors or fluid separators.

CONSTRUCTION EXAMPLES

Non-limiting examples of reactors constructed using one, two, or three, casing strings are provided as follows:-Arrangement I (Figure la): The reactor processes a single fluid and either receives the reactant fluid through the wellhead and discharges the product fluid into the rock formation, or the reactor receives the reactant fluid from the rock formation and discharges the product fluid through the wellhead.

Arrangement 2 (Figure Ib): The reactor processes a single fluid and receives the reactant fluid through the welihead and discharges the product fluid through the wellhead. Alternatively, the reactor processes two fluids. The reactor either receives two reactant fluids through the welihead and discharges the product fluid into the rock formation, or the reactor receives one reactant fluids through the welihead, and one reactant fluid from the rock formation and discharges the product fluid through the welihead.

Arrangement 3 (Figure Ic): The reactor processes two fluids. The reactor receives two reactant fluids through the welihead and discharges the product fluid through the wellhead. The reactor can be constructed to receive a reactant from the rock formation into the outermost annulus. The reactor can be constructed to discharge a product from the outermost annulus into the rock formation.

Arrangement 4 (Figure Id): The reactor is structured as two groups of boreholes (3). The Group 1 boreholes inject fluid into a rock or sediment (13). The Group 2 boreholes recover the fluid from the rock or sediment (13). The rock or sediment (13) is structured to perform as an EPB (12). Each Group (Group I and Group 2) contains one or more boreholes (3).

Arrangemenl 5 (Figure 2a): The reactor processes a single fluid and receives the reactant fluid through the wellhead and discharges the product fluid through the welihead.

Arrangement 6 (Figure 2b): The reactor processes a single fluid and receives the reactant fluid through the wellhead and discharges the product fluid through the wellhead.

Arrangement 7 (Figure 2c): The reactor processes two fluids. The reactor receives two reactant fluids through the wellhead and discharges the product fluid through the wellhead.

Arrangement 8 (Figure 2d): The reactor processes a single fluid and receives the reactant fluid through the welihead and discharges the product fluid through the welihead.

Arrangement 9 (Figure 2e): The reactor processes a single fluid and receives the reactant fluid through the welihead and discharges the product fluid through the outer casing, or receives the reactant fluid through the outer casing and discharges the product fluid through the welihead.

ArrangementS 1 to 9 can be constructed to receive one or more fluids from a rock formation, or a water body, or air, or a combination thereof. Arrangements I to 9 can be constructed to discharge one or more fluids into a rock formation, or a water body, or air, or a combination thereof.

Detailed Construction Elements Borehole reactors placed within a borehole can reuse existing boreholes or can be placed within a new borehole. The outer casing of the reactor can be the casing of the borehole (e.g. Figure 1).

Alternatively, the outer casing of the reactor is constructed from a sealed casing string placed in the borehole (e.g. Figure 2) or a new casing or liner (which can be constructed from expanded casing) placed within a borehole.

Construction of Outer Casing Within a Borehole The outer casing can be constructed using conventional casing, or expandable tubing, or a combination thereof. Expandable tubing is used to form some casings and liners (e.g. Filippov et al., 1999). The casing is placed in the borehole and a mandrel, or pig, or another type of apparatus is used to permanently mechanically deform the casing. The mandrellpig deforms the pipe by either a direct pull, or push, force, or by applying a pressure across the pipe. Figure 4 illustrates an example where the outer casing (4) is in the process of being expanded by a mandrellpig (24). The arrow (Figure 4) indicates the direction of movement for the mandrellpig, A borehole (3) is constructed using a series of lined or cased intervals (to prevent hole collapse). This results in the hole diameter decreasing with increasing depth. For example the initial section may have a 36" or 30" diameter. The next sections may have diameters of 21", 18", 16", 13 3/8", 11 3/4 9 5/8" and smaller diameters. Examples of methods of standard borehole construction are provided by Filippov et al., 1999; Lyons and Plisga, 2004; Misstear et al., 2006. Each successive casing reduces the diameter of the annulus along all or part of the boreholes length. The final liner, which is placed inside the annulus of the borehole (3), forms the outer casing (4) of the borehole reactor and is run from the wellhead to the base of the borehole. The liner may be expanded along all or part of its length. Figure 5 provides a non-limiting example of the construction of the outer casing for a conventional borehole. In a conventional borehole each casing string is not expanded. Figure 5 also provides a non-limiting example of a borehole constructed using expanded tubing. Expandable tubing can be used to convert an existing borehole (which may contain casing in poor condition, or casing of uncertain quality) into a borehole reactor. All methods of creating a seal across joints are specifically incorporated.

Expandable screens, packers, or other expandable downhole equipment may be placed in the borehole reactor. Encapsulation, or another process, may be used to allow instrumentation lines, control lines, and instruments to be used in the borehole reactor, while allowing the downhole equipment/tool to be expanded into the wall of the borehole reactor.

Switching of Fluid Flowpaths from One Annulus to Another Annulus Permeable segments and flow restrictors (e.g. seal segments and basal seal segments) are used to direct flow from one annulus to another. A non-limiting example is provided in Figures 6 and 7. In the borehole reactor illustrated in Figure 6, the borehole reactor (3) is structured to create isothermal conditions at two depth levels. The lower isothermal depth level is given the notation (25). The upper isothermal depth level is given the notation (26). Horizontal or inclined sections of the reactor are optionally used to allow the temperature in the rock formation to control the temperature of the flowing fluid.

The following notations are used for permeable segments: (27) = permeable segment forming part of the outer casing (4); (28) = permeable segment forming part of the intermediate casing (9); (29) permeable segment forming part of the inner casing (6).

In this non-limiting example (Figure 7), the lower (25) reaction zone receives a fluid through the inner most annulus (5) from the wellhead. The lower (25) reaction zone receives a fluid in the outer most annulus (7) from the rock formation, through one or more permeable segments (27) which form part of the outer casing (4). The intermediate casing (9) contains one or more permeable segments (28). These permeable segments (28) allow the fluid entering the outer annulus (7) to flow into the intermediate annulus (8). In this example the fluid enters the intermediate annulus (8) from the outer annulus at a location which is upstream of the reaction zone (16). The fluids in the innermost annulus (5) flow through one or more permeable segments (29) and enter the intermediate annulus (8) in the reaction zone (16). In this example, the two reactants are mixed within the reaction zone (16). One or more packers, or seals, or some other method (e.g. casing expansion, valves, etc.) (30) are used to prevent the fluid entering the outermost annulus (7) reaching the upper (26) reaction zone (Figure 7).

In this non-limiting example (Figure 7), the upper (26) reaction zone receives a fluid from the lower reaction zone (25) through the intermediate annulus (8). In this example one or more packers, or seals, or some other method (e.g. casing expansion, valves, etc.) (31): (i) require the fluid within the intermediate annulus (8) to enter the reaction zone (16) located in the outer annulus (7) through the perforated segment (28) and (ii) require the product fluid to leave the reaction zone (16) through the outermost annulus (7).

Construction of a Membrane Reactor Unit or Membrane Separation Unit (Membrane Unit) Membranes used in conventional membrane reactors are fragile, susceptible to damage, and may fracture or crack when subject to stress (e.g. ceramic membrane). The borehole reactor overcomes this problem by using the casing as a structural frame. The structural frame is constructed from one or more segments. These segments are impermeable segments, or permeable segments, or retaining screen segments, or screen segments, or seal segments or basal seal segments or a combination thereof. This allows the membrane units to be constructed using conventional casing material and treated in the same manner as conventional casing, during installation. The membrane is constructed from one or more of organic material, ceramic material, another form of material. The membrane can be constructed as a coating bonded to the membrane unit or a membrane material which is wrapped around, or contained within the membrane unit, or a combination thereof. The membrane can be fastened to the membrane unit. The borehole reactor can be constructed to contain a catalytic membrane, or a fluid separation membrane, or a combination thereof.

The efficiency of a conventional membrane increases with the pressure differential across the membrane. The borehole reactor can be constructed and operated to have a higher pressure differential across a membrane than a conventional membrane reactor or separator. The borehole reactor can be constructed and operated to have a lower pressure differential across a membrane than a conventional membrane reactor or separator. The borehole reactor can be constructed and operated to have the same pressure differential across a membrane as a conventional membrane reactor, or separator. This flexibility can be used to increase the efficiency of many fluid separation and catalytic membrane operations when the membrane is constructed as part of a casing string contained within a borehole reactor.

A membrane unit (32) is constructed from casing segments of any suitable length (Figure 8a). In the preferred embodiment the permeable segment is used to form the structural frame. Part (or all) of each permeable segment contains a porous and permeable (or permeable) structural frame (33). In the preferred embodiment, the ends (34) of each segment (32) are optionally constructed from impermeable material and can be used to connect the membrane unit (permeable segment) to another membrane unit, or segment [e.g. permeable segment, impermeable segment, seal segment, basal seal segment, retaining screen segment, screen segment], or another type of casing (or casing segment), or the welihead, or a combination thereof.

In some embodiments the entire membrane unit will be constructed from a porous and permeable (or permeable) structural frame. The porous and permeable structural frame is coated on the outside, or coated on the inside, or impregnated with, or a combination thereof, with a membrane (35) (Figure 8a).

The porous and permeable structural frame can be constructed from a membrane (35), which is either porous and permeable, or permeable, or a combination thereof. The membrane can optionally contain a catalyst, or a filtrate, or an adsorbent/absorbent, or a combination thereof, and can (optionally) be used for fluid separation.

1. Figure 8a illustrates a flow through membrane unit where a fluid (36) flows through the annulus. Part of the fluid (37) flows through the membrane. The residual fluid (38) leaves the membrane unit through the annulus. In some embodiments a fluid (37) will flow into the annulus through the membrane.

2. Figure 8b illustrates an example where collars (39) (or another form of apparatus) are placed on the casing to ensure separation between the membrane unit and adjoining casings within the borehole. Collars (39) can be placed on any impermeable segment, permeable segment, screen segment, retaining screen segment, seal segment, basal seal segment.

3. Figure 8c illustrates an example where a protective structure (40) is placed around the casing segment to protect the membrane (35). The protective structure is permeable or porous and permeable. A protective structure (40) can be placed on any impermeable segment, permeable segment, screen segment, retaining screen segment, seal segment, basal seal segment.

Figures 8a to 8c illustrate examples where a membrane is placed on a structural skeleton, in order to overcome the abrasions, jars and shocks associated with installation and operation, which would otherwise result in the membrane fracturing, or being otherwise damaged, during installation or operation. The annulus within a membrane unit can contain structural supports (41). These structural supports (41) can take any form and may compartmentalise the annulus (e.g. Figure 8d).

1. Figure 8d illustrates a non-limiting example cross section (perpendicular to the direction of fluid flow) through a membrane unit. An optional structural support (41) divides the annulus into four segments. Structural supports (41) can be used to optionally divide the annulus into two, or more, longitudinal conduits. The fluids flowing in each longitudinal conduit may flow in different directions. A structural support (41), when present, can be a structural frame and need not divide the annulus into two or more longitudinal conduits.

2. Figure 8e shows a schematic non-limiting example longitudinal cross section through a membrane unit which has been subdivided into two annuli by a structural support or separating wall (41). Figure 8e illustrates a perforated zone, or slotted zone, or permeable zone, or gap, or a combination thereof (42) in the separating wall (41) which allows fluid to pass from one annular volume into the adjoining annular volume. Fluid enters or leaves the membrane unit through the membrane (35).

In some applications it is desirable to construct a membrane unit (32) where the membrane is placed within the atmulus of the membrane unit. Figure 8f illustrates an example where one or more membranes (43) have been placed in the annulus of the membrane unit. A conduit (44) connects each membrane (43) and allows fluid to be removed from, or added to the membrane (43). Optional seals (45) or sealing centralisers (45) may be present to restrict fluid flow within the annulus of the membrane unit.

Figures 8g and 8h illustrate examples of a forced flow through the membrane where a packer, or seal, or another apparatus (30, 31, 45) requires all or part of the fluid in the annulus to flow through the membrane containing the reaction zone.

1. Figure 8g illustrates a membrane unit where fluid in the annulus is forced to flow through the catalytic membrane. In some embodiments the fluid flows will be reversed.

2. Figure 8h illustrates a construction where fluid in an amiulus outside the membrane unit, is forced to flow through the catalytic membrane and into the annulus of the membrane unit. In some embodiments the fluid flows will be reversed.

When the membrane is constructed as a porous and permeable surface it can have a unimodal, or a multimodal pore diameter distribution.

Membrane units are constructed from one or more impermeable segments, permeable segments, seal segments, retaining screen segments, screen segments, basal seal segments.

Construction of Reaction Zone Units One or more segments selected from permeable segments, impermeable segments, retaining screen segments, screen segments, seal segments, basal seal segments are used to construct reaction zone units (46). Reaction zone units are optionally constructed to be removable. These reaction zone units (46) contain a reaction zone (16). Non-limiting examples are provided in Figure 9 as follows:- 1. Figure 9a: Flow through reaction zone (16): Each reaction zone unit may contain (optional) retaining screens (47) which are designed to ensure that the reaction zone (catalyst, filtrate, absorbentladsorbent) remains in the reactor unit during installation and operation. The reaction zone in each reaction unit is structured as one or more of a packed bed reactor, fixed bed reactor, fluidised bed reactor, slurry reactor, oscillating flow reactor, pulsed flow reactor, expanding bed reactor. The catalyst, filtrate, absorbent/adsorbent is held in the reaction zone unit (46) as a solid, or liquid, or a combination thereof. One or more retaining screens may be removable to allow the catalyst, filtrate, absorbent/adsorbent to be removed, or loaded, or replaced as required.

2. Figure 9b: Flow through reaction zone (16), constructed from a membrane unit (32). In this example two reactants are mixed in the reaction zone.

3. Figure 9c: Flow through reaction zone (16), constructed from one or more permeable segments. In this example two reactants are mixed in the reaction zone.

4. Figure 9d: Forced flow through reaction zone (16) containing a sealed base or seal (45).

5. Figure 9e: Forced flow through reaction zone (16) where a fluid enters and leaves the reaction zone through the permeable walls of the annulus.

Reaction zone segments are constructed from one or more impermeable segments, permeable segments, seal segments, retaining screen segments, screen segments, basal seal segments. The reaction zone unit may contain one or more optional screens (47), or retaining screens (47). The reaction zone (16) is placed within an outer annulus, or an intermediate annulus, or an inner annulus, or a combination thereof. In some embodiments reaction zone units may be used to separate one or more fluids.

CONSTRUCTION OF A BOREHOLE REACTOR

The borehole reactor is constructed from one or more impermeable segments, permeable segments, basal seal segments, seal segments, retaining screen segments, screen segments. These can be used independently, or combined, to create one or more reaction zones (Reaction Zone Segments) which are operated in series or in parallel or a combination thereof within the reactor. Permeable segments are used to create zones where fluids can flow from one annulus to another. They are also used to create zones where fluid can enter or leave the reactor through the outer casing. Permeable segments are also used to create fluid separation membranes and membranes containing one or more of catalyst, filtrate, adsorbent, absorbent.

Segments used to Construct a Reactor The borehole reactors are created from a series of standard casing units, or customised casing units.

These units can be constructed prior to insertion into a borehole, In some embodiments the perforated interval adjoining a rock formation will be constructed in the borehole after the outer casing (4) has been installed. The reactor is constructed by joining casing segments and optionally by placing one or more casing segments within the outer casing (e.g. Figures 1, 2).

The borehole reactor is constructed using one or more of the following standard or customised casing units: 1 Impermeable Segment: Figure: 1 Oa: Lengths of casing constructed from impermeable material. These casing lengths can be used to create removable units (46) containing one or more reaction zones.

2. Permeable Segment: Figure lOb: Lengths of casing containing one or more perforated intervals, slotted intervals, porous and permeable intervals, permeable intervals. Lengths of casing constructed from impermeable material can contain one or more perforated intervals, slotted intervals, porous and permeable intervals, permeable intervals (e.g. Figure 1 Oc; I Od; lOe). These casing units can be used to create one or more of forced flow membrane units (e.g. Figure 8), fluid mixing units where the fluids are mixed within the reaction zone or within an annulus (e.g. Figures 7, 9), fluid separation units (e.g. Figure 8a), fluid transfer units which are designed to allow fluid to flow from one annulus to another (e.g. Figure 7), fluid transfer units which are designed to allow fluid to flow from the rock formation into the annulus (e.g. Figure 7), or fluid transfer units which are designed to allow fluid to flow from the annulus into a rock formation. A permeable segment can be constructed by perforating an impermeable segment. The perforations may be undertaken in the borehole to ensure that fluid enters or leaves the outer casing at a specific depth or passes from a specific rock formation into the reactor; The pores can be constructed as tuyeres. Tuyeres can have any shape or form.

3. Seal Segment or Basal Seal Segment: Figure 1 Oc: 1 Od: Lengths of casing which are constructed from impermeable material (Figure 1 Oa) or contain (Figure lOb) one or more perforated intervals, slotted intervals, porous and permeable intervals, permeable intervals, or a combination thereof, and contain a seal (45) [seal segment}(Figure lOc) or a sealed base (10) [basal seal segment] (Figure lOd). The seal can be a valve, 4. Retaining Screen Segment or Screen Segment: Figure I Oe: Lengths of casing which are constructed from impermeable material or contain one or more perforated intervals, slotted intervals, porous and permeable intervals, permeable intervals or a combination thereof, and contain one or more retaining screens (47) or screens (47). Lengths of casing containing a retaining screen or screen can also contain a sealed base (10) or seal (45). Non-limiting examples of retaining screens include gas distributors, tuyeres, bubble cap distributors, spargers or pipe-grid distributors (Or multi-pipe distributors), perforated plate distributors, mesh screens, membranes, permeable plates, porous and permeable plates, membrane plates, membrane discs, porous and permeable monoliths, porous monoliths. Non limiting examples are provided by Green and Perry (2008). Membrane discs and plates may optionally contain catalyst, or absorbent/adsorbent, or filtrate, or a combination thereof. Membrane discs can be constructed as monoliths which fit inside the casing to form zones of continuous membrane material (Figure 101). The structure illustrated in Figure 1 Of is used to construct a flow through membrane reactor, where the membrane contains one or more of catalyst, absorbent, adsorbent, filtrate. A screen segment contains one or more screens and can contain a seal. A retaining screen segment contains one or more retaining screens and can contain one or more screens or seals. A screen can be a plate which partially covers the annulus.

a.A retaining screen is designed to retain one or more of particulate matter, solid matter, specific liquids within the reaction zone. Reactants can enter the reaction zone through a retaining screen.

b.A screen allows fluids (and can allow some or all entrained particulate matter (within the fluid)) flowing within the annulus to pass from one side of the screen to the other.

A screen can take any form or structure and can be made of, or contain catalyst. It can optionally be used to provide a form of energy to the flowing fluid within the annulus, * including but not limited to heat, magnetic force, electric field, electric charge, electromagnetic field, ultrasound field, radiowave field, microwave field, laser field or another form of field. The screen can optionally be used to contain measurement equipment, including but not limited to pressure measurement, temperature measurement, flow measurement, chemical concentration measurement, or another form of measurement.

Seal or Screen Fixings: Figure 1 Of: 1 Og: 1 Oh: 1 Oi: The retaining screen (47), or screen (47), or seal (45) or basal seal (10) will be held in position within the casing unit. The seal, basal seal, screen, retaining screen is fixed in place by welding or by some other means of attachment. In some embodiments the seal, or screen, or retaining screen, or basal screen will be removable, and can be replaced. In other embodiments they are permanently fixed within the casing segment. Non-limiting examples of fixings are provided as:- 1. Figure 1 Of illustrates a non-limiting example where the retaining screen (47) is held in place at its upstream surface and downstream surface by fixings (48) within the casing annulus.

2. Figure lOg illustrates a non-limiting example where the retaining screen (47) is held in place by a single set of fixings (48) within the casing annulus. The retaining screen may be held in place by gravity and rest on a ledge as illustrated in Figure lOg. The fixings (48) may be constructed as part of an integral unit which may extend either side of the ledge (48) or may be attached to a set of extensions (49). These extensions (49) may be bolted, or welded, or riveted, or fixed by some other method to the casing.

3. Figure lOh illustrates a non-limiting example where the retaining screen (47) is held in place by two sets of fixings (48, 50) within the casing annulus. The retaining screen rests on a ledge as illustrated in Figure lOh. The fixings (48) may be constructed as part of an integral unit which may extend either side of the ledge (48) or may be attached to a set of extensions (49). These extensions (49) may be bolted or welded or riveted, or fixed by some other method to the casing. The fixings (48) upstream and downstream of the retaining screen (47) may be permanently fixed in place.

Alternatively, one set of fixings (50) or both sets of fixings (48, 50) will be removable, to allow the retaining screen (47) or seal (45) to be removed, or replaced, when the casing unit is removed from the reactor.

4. Figure 1 Oi illustrates a non limiting example where seals (51) or gaskets (51) have been placed between the retaining screen (47), or seal (45), or basal seal (10) and the fixings (48, 50).

In some embodiments one or more small casing units (e.g. Figure lOj) containing the retaining screen (47), or retaining screen unit (47), or seal (45), or basal seal (10) will be fixed to a membrane unit, or a reaction zone or permeable segment or impermeable segment to form a screen segment (47), or retaining screen segment (47), or seal segment (45), or basal seal segment (10).

In some embodiments the retaining screen (47), or screen (47), or seal (45), or basal seal (10) will be replaced by a valve (52) or protrusions or flow restrictions (21, 22, 23).

In some embodiments the retaining screen (47), or screen (47), or seal (45), or basal seal will be welded into the casing. In other embodiments the retaining screen (47) or retaining screen unit (47) or seal (45) will be screwed into or bolted into the casing or fastened by another method. Fixed or removable bars (53) may be used in some embodiments (Figure 10k) to hold and position, or position, or hold, a retaining screen (47), or screen (47), or seal (45), or basal seal (10). In some embodiments removable bars (53) may be used to create protrusions or flow restrictions (21, 22, 23).

Construction of Different Fluid Flow Arrangements The various borehole reactors illustrated in Figures 1, 2 can be constructed by combining the different casing segments. These segments can be combined in a large number of different combinations to produce reactors and fluid separators which are suitable for a variety of applications.

A variety of non-limiting borehole reactor structures constructed using the modular arrangements described in Figures 1 to 10 are illustrated in Figure 11. In each illustrated non-limiting example the reaction zone (16) is shown as being present in an annulus. In each case the catalyst, filtrate, absorbent/adsorbent is either located in the annulus (e.g. particulate material, monoliths, containers), or is present as a coating on one or more walls within the reactor, or a combination thereof. The coated walls can be an external wall or an internal wall of a casing string (Figure 12a, l2b). These coated casing walls may be impermeable (e.g. coated wall reactor), permeable, or porous and permeable (e.g. membrane reactor).

1. Reactor Constructed to Process a Single Fluid a. Figure 11 a: The reactant enters the reactor through the outer casing (4) and the product fluid leaves the reactor through the wellhead. This reactor is created using 1. a permeable segment (Figure lOb) with an attached seal segment, or a permeable segment (Figure lOb) incorporating a basal seal (10) (Figure IOj) (or a seal (45) (Figure lOj)). The basal seal (10) can be replaced by a cement plug, or another sealing method, which is designed to create a basal seal (10) which isolates the reactor from the rock formation.

2. a flow through reaction zone (Figure 9a), or the reaction zone can be created using a casing string (Figure 1 Oa) containing the reaction zone, plus retaining screen (47) segment (Figure 1 Oj) or alternatively using a casing unit containing a flow through membrane unit (Figure lOg; lOh; 101). The reaction zone (16) may be held in place using one or more retaining screens (47) constructed in accordance with the illustrations in Figure 10 or by another method.

b. Figure 11 b: The reactant enters the reactor through the wellhead (I) and the product fluid leaves the reactor through the outer casing (4). This reactor is constructed using the various arrangements described for the reactor illustrated in Figure 11 a.

C. Figure 11 C: The reactant enters the reactor through the wellhead and the product fluid leaves the reactor through the wellhead. This reactor is created by using:- 1. wide diameter impermeable segments (Figure lOa) to form the outer casing (4) and a basal segment containing a basal seal or seal (e.g. [Figures lOc and lOd (without (27 or 28 or 29))] or Figure lOj). The basal seal (10) can be replaced by a cement plug, or another sealing method, which is designed to create a basal seal (10) which isolates the reactor from the rock formation.

2. Narrower diameter reactor/casing strings are constructed in accordance with the design for the reactors illustrated in Figure 11 a to form the inner casing (6) and perforated zone (29). Stabilisers, centralisers, packers or another form of positioning apparatus may optionally be used to position the internal reactor units (6,29) within the aimulus (7) of the outer casing (4).

d. Figure lId: The reactant enters the reactor through the welihead and the product fluid leaves the reactor through the wellhead. This reactor is constructed using the various arrangements described for the reactor illustrated in Figure II c.

2. Reactor Constructed 10 Process Two Fluids a. Figure lIe: One reactant enters the reactor through the wellhead (1), the other reactant enters the reactor through the outer casing (4) before passing into the inner annulus (5). Product fluids are confined to the inner annulus (5) and leave the reactor through the wellhead (1). This reactor is created by using:- 1. wide diameter impermeable casing segments (Figure 1 Oa) to form the outer casing (4) and a basal permeable segment containing a basal seal or seal (e.g. Figures 1 Oc and 1 Od) or a permeable segment (Figure lOb) plus a segment containing a basal seal or seal (Figure lOf; lOg; IOh;lOi;lOj). The basal segment can be replaced by a cement plug, or another sealing method, which is designed to create a basal seal (10) which isolates the reactor from the rock formation.

2. Narrower diameter reactor/casing strings constructed in accordance with the design for the reactors illustrated in Figure 11 a. They form the inner casing (6) and a perforated zone (29) constructed from one or more permeable segments containing a reaction zone (16).

An optional valve (52) (e.g. Figure lOj) is placed at the base of the perforated interval containing the reaction zone. One or more permeable segments (Figure lOb), or impermeable segments (Figure lOa) are placed below the reaction zone. An optional seal (10,45) may be placed at the base of the lowest casing segment.

Stabilisers, centralisers, packers or another form of positioning apparatus may optionally be used to position the internal reactor units (6,29) within the annulus (7) of the outer casing (4).

3. A seal (30, 31) which may be formed from an expandable packer or by some other apparatus is placed in the outer anriulus (7).

b. Figure 1 If: Two reactants enter the reactor through the wellhead (I). Product fluids leave the reactor through the outer casing (4). This reactor is constructed using the various arrangements illustrated in Figure lIe.

C. Figure 1 lg: One reactant enters the reactor through the wellhead (I) and is confined to the inner annulus (5) before entering a reaction zone in the outer annulus. The other reactant enters the outer annulus (7) through the outer casing (4). Product fluids are confined to the outer annulus and leave the reactor through the wellhead (1). This reactor is constructed using the various arrangements described for the reactor illustrated in Figure lIe modified as follows:- 1. The valve (52)(Figure I If) is either replaced by a seal (45) (Figure lOj) or by a sealed impermeable segment (Figure lOa) extending below the reaction zone and containing a seal (45) or basal seal (10) (Figure lOj). In the illustrated embodiment the base of the inner casing rests on the basal seal (10) of the outer casing. In some embodiments the base of the inner casing will be suspended above the basal seal (10) of the outer casing.

2. The seal (30,31) (Figure lIt) is either replaced by a valve (52) or is dispensed with.

d. Figure 1 Ih: Two reactants enter the reactor through the wellhead (I) and are confined to the intermediate annulus (8) and outer annulus (7) before entering a reaction zone in the inner annulus (5). The reactants are mixed in the reaction zone (16). Product fluids are confined to the inner annulus and leave the reactor through the wellhead (1). This reactor is constructed as follows:- 1. Wide diameter impermeable segments (Figure 1 Oa) form the outer casing (4) and a basal impermeable segment (Figure lOa) containing a basal seal (10) or seal (45), or an impermeable segment (Figure lOa) plus a segment containing a basal seal or seal (e.g. Figure lOf; lOg; lOh;IOi;lOj). The basal seal segment can be replaced by a cement plug, or another sealing method, which is designed to create a basal seal (10) which isolates the reactor from the rock formation.

2. Narrower diameter impermeable segments (Figure lOa) form the intermediate casing (9). A permeable segment (Figure lOb) is placed at the base of the casing string to allow fluid contained in the outer annulus to flow into the intermediate annulus. The base of this casing string contains an optional basal seal or seal (e.g. Figure I Oj).

3. Narrow diameter reactor/casing units constructed in accordance with the design for the reactors illustrated in Figures 1 If form the inner casing (6) and a perforated zone (29) containing a reaction zone (16). An optional valve (52) may be present in the inner annulus.

4. A seal (30, 31) which may be formed from an expandable packer or by some other apparatus is placed in the intermediate annulus (8).

This seal can be an integral part of the casing segment.

e. Figure 1 li: Two reactants enter the reactor through the wellhead (1) and are confined to the inner annulus (5) and intermediate annulus (8) before entering a reaction zone in the outer annulus (7). The reactants are mixed in the reaction zone (16). Product fluids are confined to the outer annulus and leave the reactor through the wellhead (1). This reactor is constructed as follows:- 1. The outer casing is constructed in accordance with the construction methodology for the outer casing in the reactor illustrated in Figure I lh, 2. The intermediate casing is constructed in accordance with the construction methodology for the inner casing in the reactor illustrated in Figure 1 Ih, 3. The inner casing is constructed in accordance with the construction methodology for the intermediate casing in the reactor illustrated in Figure 11 h. The inner casing has a smaller diameter than the intermediate casing.

f. Figure 1 Ij: Two reactants enter the reactor through the wellhead (1) and are confined to the inner annulus (5) and outer annulus (7) before entering a reaction zone in the intermediate annulus (8). The reactants are mixed in the reaction zone (16). Product fluids are confined to the outer annulus and leave the reactor through the wellhead (I). This reactor is constructed as follows:- 1. The outer casing is constructed in accordance with the construction methodology for the outer casing in the reactor illustrated in Figure 1 lh 2. The intermediate casing is constructed in accordance with the construction methodology for the intermediate casing in the reactor illustrated in Figure 1 lb 3. The inner casing is constructed in accordance with the construction methodology for the inner casing in the reactor illustrated in Figure 11g.

4. A seal (10, 45) (e.g. Figure l0j) is placed in the inner annulus below the reaction zone to prevent the two reactants mixing outside the reaction zone.

These non-limiting constructions are provided to illustrate operability. The number of permutations is large and increases as the number of separate fluid streams processed in a reaction zone increases. A reactor can be constructed to process more than two fluids. The reactor can be constructed to deliver different fluids to different parts of the reactor. The reactor can be constructed to recover different fluids from different parts of the reactor.

Construction of Different Reactor Types Using Reaction Zone Units A reaction zone (16) is created by placing one or more of catalyst, filtrate, adsorbent, absorbent in an aimulus or flowpath within the reactor. A reaction zone (16) is constructed from one or more reaction zone units. Reactants may be corrosive and may operate at elevated temperatures and pressures.

Consequently, an appropriate casing material will be used to construct the reactor. The casing may be coated to protect it from the adverse effects of temperature, and chemicals, or fouling. This coating can be an insulant.

Reaction zone units are used to construct one or more of the following reactor types:- 1. Coated wall reactor: A coating containing one or more of catalyst, filtrate, adsorbent, absorbent is placed on the appropriate wall of one or more casing segments or sections of casing. The coating can be a porous membrane, porous and permeable membrane or another form of coating or plating. Non-limiting examples are provided in Figures 1 2a, I 2b.

a. Figure 12a illustrates a coating (54) placed on the exterior of a casing segment or section. The coating covers all or part of the casing segment or section.

b. Figure 12b illustrates a coating (54) placed on the interior of a casing segment or section 2. Forced flow through membrane reactor. Figure 8 provides non limiting examples of casing sections or segments which can be used to construct a forced flow through membrane reactor (e.g. Figure 8g, 8h) or a fluid separation membrane reactor (e.g. Figures 8a; 80.

3. Wire reactor: Wire coated with one or more of catalyst, filtrate, adsorbent, absorbent can be placed in a reactor unit (e.g. Figure 9a, 9b, 9c, 9d). In some embodiments the wire will be placed as a series of structured screens (47) (e.g. Figure 12c). This reaction zone is created using standard casing units (Figure 1 2c) or by combining a series of smaller casing segments containing a screen (e.g. Figure l0j). In some embodiments the reaction zone will be created by placing the wire (containing one or more of catalyst, filtrate, adsorbent, absorbent) in one or more containers (55) within a casing unit (Figure 12d). There is no preferred method of holding the containers within the casing unit. Figure 12d illustrates an example where each unit is held in place using a combination of fittings (48, 50) and seals (51).

4. Flow through Monolith or Disc Membrane reactor: The reaction zone is created by fixing one or more monoliths, discs, membrane monoliths, membrane discs within the reactor. The methods which can be used to fix the units in place are identical to those used to place a seal or a screen within the reactor. Non limiting examples of suitable arrangements are provided in Figures 10 and l2c;12d. Monoliths and discs are made of any suitable material and may contain, or be coated with, carbon nanotubes (which can contain one or more of catalysts, filtrate, absorbent, adsorbent). Monoliths and discs contain any suitable internal structure and are permeable, or porous and permeable, or a combination thereof.

5. Flow through reactor unit containing particulate material: The reaction zone is created by placing particulate material within a reactor. Retaining screens (47) are used to control the amount of pore expansion that can occur within the reaction zone. Non limiting examples of suitable arrangements are provided as:-a. Figure 12e: Packed bed reactor: The particulate material fills the reaction zone.

Porosity expansion is prevented by the upper and lower retaining screens (47). In some embodiments one or more conduits (56) may be used to assist in the removal of fluids from the reaction zone (Figure 120.

b. Figure 1 2g: Particulate bed reactor, or expanding bed reactor, orfluidised bed reactor, or slurry reactor, or pulsed flow reactor, or oscillating flow reactor: The particulate material is allowed to expand during operation. The particle bed (when at rest) occupies only part of the annular volume between the upper and lower retaining screens. The annular volume (57) which is devoid of particles when the particle bed is at rest, controls the amount of porosity expansion that can occur within the particle bed during operation. The downstream retaining screen can be absent. The upstream retaining screen can be absent. In some embodiments the reactor zone will be replaced by an EPB or function as an EPB.

C. Reaction zone placed within containers in the annulus. In some embodiments the particulate material will be placed in containers which may have one or more of porous and permeable, permeable, impermeable sides, top and base. These containers may be fixed in place within a reaction zone. Non limiting examples of the types of arrangements which may be used are provided in Figure lOf to lOj and 12c, 12d, 12h. In other embodiments it is desirable to be able to remove and replace the catalyst, filtrate, absorbent, adsorbent without removing the casing (and in some embodiments without removing the welihead). Direct access to the interior of an annulus may be provided through the wellhead. In some embodiments as illustrated in Figure 12h a series of linked (58) containers (55) (containing one or more of catalyst, filtrate, absorbent, adsorbent, inert material, reactant) are lowered into the reaction zone using a wireline or chain or another method (59). The wireline or chain or another method (59) is used to remove the containers (55). The containers are retained in place by a ledge (48, 50) or protrusion (21,22,23) or by another method or seal (10, 45) or screen (47). Protrusions (2 1,22,23) may be placed within a standard casing unit or constructed as a standalone unit (e.g. Figure lOj). The containers (55) can be constructed to fit within an inner annulus, or to fit within an outer annulus or to fit within an intermediate annulus. The containers can have any shape or form and can be recoverable through the wellhead.

A reaction zone can be constructed to undertake more than one type of operation and may incorporate more than one type of reactor and may include a fluid separation membrane. Reaction zones can be placed in series within a reactor.

In some embodiments it is desirable to operate a number of reaction zones in parallel within the annulus, where each reaction zone is confined to a separate inner casing (or conduit (11) (Figure le)) (constructed from casing and placed in one or more of an outer annulus and an intermediate annulus). A non-limiting example of a cross section through a reactor containing a number of inner annulus within an outer annulus is illustrated in Figure 12i. This non limiting example allows the reactor to operate as a multi-tubular reactor. Figure 12i also illustrates non limiting examples where casings are used to create a multi-tubular reactor within an inner annulus and within an outer annulus. Casings placed in the intermediate annulus can be used to create a multi-tubular reactor, or a reactor containing a number of reaction zones operating in parallel, or both in series and in parallel. Individual tubes within a multi-tubular reactor are constructed from casing. Each tube can contain one or more casing strings within its annulus. A non limiting example of a casing (69) placed within a tube is provided in Figure 12i(i). This casing can be used to deliver reactants, or remove products, or provide a heat management system, or provide access for measurement equipment, or may have another purpose.

Conduits (11) (Figure le) can be placed in the annuli to activate a catalyst or clean catalyst/filtrate or clean a membrane, or to assist with starting the reactor, to assist with heat flow management within the reactor, to locate sensors within the reactor, or for another purpose.

APPLICATIONS

Figures 1 to 12 illustrate that the borehole reactor can be created using either standard casing units (or segments) or customised casing units (or segments). This flexibility reduces the construction cost for a reactor, the time taken to construct a reactor, and reduces the skill level required to construct a reactor.

For example, a reactor selected from any of the reactor types illustrated in Figure 11 with a length of 10 ->100 m could be constructed and installed on site within a borehole in a period of<l ->3 days. A borehole reactor in a borehole >3000 m long could be installed within a period of<I to >7 days. This represents a step change in construction time, when compared with an equivalent capacity fixed bed reactor, or membrane reactor or fluidised bed reactor where construction times are typically in the range <1 month to >24 months.

The ability to construct the reactor using standard casing (and standard units (or segments) constructed from casing) results in a substantial cost saving, and time saving, when compared with a conventional fixed bed reactor, or membrane reactor, or fluidised bed reactor.

The construction of the reactors from casing with a diameter to length ratio of less than or equal to 0.2 allows the reactors to have an increased strength (for a specific wall thickness) than a conventional fixed bed reactor, or membrane reactor or fluidised bed reactor. This allows the reactors to be able to sustain a higher pressure differential between the pressure within the reactor and the pressure outside the reactor than a conventional fixed bed reactor, or membrane reactor, or fluidised bed reactor.

The placement of the reactor within a borehole results in the fluid pressure outside the borehole increasing with increasing depth. This provides an external support to the reactors outer casing and allows the reactor to: 1. operate at higher pressures than a conventional fixed bed reactor, or membrane reactor, or membrane separator, or fluidised bed reactor; 2. contain a greater weight of reactants and products within the reactor than a conventional fixed bed reactor, or membrane reactor or fluidised bed reactor; 3. contain a greater weight of catalyst than a conventional reactor.

The placement of the reactor in a borehole reduces the footprint required for a plant, and therefore releases land for other uses. It also allows chemical reactions to be undertaken offshore, by removing a requirement for a platform, or ship, or floating mobile unit to contain the reactor.

The reactor configurations outlined in Figures 1 -12 can be used as a substitute for any process which requires a fixed bed reactor, or membrane reactor, or membrane separator, or particulate bed reactor, fluidised bed reactor, slurry reactor, pulsed flow reactor, expanding bed reactor, oscillating flow reactor and processes a substantial fluid volume (e.g. <10 to >l07m3 day). The reactor configurations can also be used to process fluids using high pressure non-catalytic reactions or reactions where the catalyst and reactants are fluids. Non-limiting example applications include: 1. reform carbon dioxide to produce a synthesis gas; oxidise CH4 and other organic chemicals to produce C02; 2. partially oxidise CH4 and other organic chemicals to produce a synthesis gas containing CO; reform CH4 and other organic chemicals to produce a synthesis gas; 3. convert one or more of carbon dioxide, carbon monoxide, methane, hydrocarbons, organic chemicals, hydrogen, synthesis gas, to hydrocarbons, or methane, or one or more organic chemicals, or water, or a combination thereof; produce hydrocarbons using the Fischer Tropsch and related processes from synthesis gas; 4. manufacture biodiesel using catalytic, or non catalytic processes, or a combination thereof; 5. process or treat water; 6. desalinate water; 7. undertake catalytic reactions to produce one or more of organic chemicals anil inorganic chemicals; 8. separate fluids; 9. process fluids using an absorbent, or adsorbent, or filtrate, or a combination thereof.

In order to illustrate operability and different aspects of the invention a number of specific applications are highlighted:-I. Removal of carbon dioxide from a coal power stations flue gas 2. Desalination of water 3. Production of synthesis gas from natural gas 4. Production of Fischer Tropsch hydrocarbons from synthesis gas 5. Reactor configurations for Partial Oxidation Al. Application 1: Removal of carbon dioxide from a coal power stations flue gas The flue gas from a typical coal fired power station has a composition of 10.9% C02, 0.0 1% CO, 9% H2, 3.01% CH.4, 3% 02, 0.106% SO2, 75.854% N2 + Ar (e.g. Mazumder et al., 2006). A typical 1000 MWhr pulverised coal-fired Electricity Generating Plant will emit 6 -8 x I 6 CO2 equivalent per year (Koo and Tan, 2006). 6.8 x 106 t CO2 equivalent per year is constructed as 39.6 m3 CO2 + 10.9 m3 CH4 (396 m3 s' Flue Gas). Volumes are measured at 00 C (273 K) and atmospheric pressure. Flue gas compositions and volumes vary between power stations and may vary with time.

The borehole reactor can be used to catalytically react the C02, 0.01% CO, 9% H2, 3.01% CH4 contained in the flue gas to produce either a marketable product, or a product which has a lower global warming potential than the existing flue gas, or a product which can be sequestered, but has a smaller volume (when sequestered) than C02, thereby increasing the net storage capacity and operating life of a sequestration reservoir.

There are a variety of chemical approaches which can be used remove the CH4 (the principal carbon containing global warming gas within the flue gas), thereby allowing the flue gas to be vented into the atmosphere, or allowing the products to be used for another purpose.

Two processes which can be used to convert the residual CH4 in the flue gas to CO2 are:-o Oxidation or partial oxidation of the CH4 to C02/CO (CH4 + x02 = CO, + aH2O + bH2) o Carbon dioxide reforming of CH4 (with or without the addition of 02) Other processes can convert the CO2 and Cl-L1 to carboxylic acids (e.g. CH4 + CO2 CH402) or other products.

Four non-limiting groups of examples are considered:- 1. Partial oxidation/carbon dioxide reforming of the flue gas The typical flue gas molar ratio of 10.9% C02, 0.01% CO, 9% H2, 3.01% CH4, 3% 02 will, if passed over an Ni/Al203 catalyst, or another catalyst (at an elevated temperature (e.g. >200 ->950 C)) result in a proportion of the CH4 being converted to CO2 and CO. At 800° C this conversion rate may exceed 90%. The catalyst is held on a support (e.g. alumina) or is present as a metal. This non-limiting example uses a wire or foil catalyst (examples include but are not limited to one or more of Ni, Co, Cr, W, Mo, Fe, Ti). The temperature of the wire is maintained at the required reaction temperature by a mixture of an exothermic reaction on the wire and an applied electric current or electrically generated temperature on or beside the wire. Application 5 considers a catalyst held on a support (e.g. alumina, particles, monolith, disc, inerts, another type of structure or support).

The lobal warming potential of 396 m3 s' Flue Gas is 134 m3 s' CO2(Equivalent), calculated as 43.16 m3 s CO2 plus 11.9 m3 s' CH4 [with a global warming potential calculated as 21 x 11.9 x {Weight oft mole of CH4 (16 gms)/ Weight oft mole of CO2 (44 gms)}]. The global warming potential of It CH4 is considered (Lide, 2008) to be equivalent to 21 t CO2.

A non-limiting example application based on the use of cobalt wires (or cobalt coated wires) may have a gas hourly space velocity (GHSV) of 2.65 x106 m3 CH4 hr m3 Co (300,000 m3 CH4 hr' t1 Co). A reactor processing 11.9 m3 s' CH4; 396 m3 s' Flue Gas) will require 0.014 m3 Co wire (0.12 t Co wire).

A reaction temperature of 800° C on the wire with a flowing gas temperature which may be <800° C (e.g. 200 -700° C) through the reaction zone would be expected to change the flue gas (CO + CH4 components) composition from 10.9% CC2, 0.01% CC, 3.01% CH4 to 14.6% CON, 0.3% CH4 (assuming 90% CH4 conversion to CO, CO2, H2 and H20). Discharging the product gas into the atmosphere would reduce the global warming potential of the flue gas from 134 m3 s' (CO2 equivalent) to 66.88 m3 s' (CO2 equivalent), calculated as 57.8 m3 s' CO2 plus 1.188 m3 s1 CH4 [with a global warming potential calculated as 21 x 11.9 x {Weight of I mole of CH4 (16 gms)/Weight of 1 mole of CO2 (44 gms)}]; (i.e. a >50% reduction in global warming emissions). I m3 CO2 weighs 1.964 kg. Non-limiting example reactor configurations are illustrated in Figures lIc, lid.

This non-limiting example demonstrates that a heated wire catalyst held within a borehole reactor can substantially reduce the global warming potential of the flue gas. The reactor requires one or more wire reaction units which are either connected via electric cables to an electricity supply, or are able to receive a flue gas which has been heated to the required temperature prior to entering the reaction zone, or a combination thereof. The same reaction can be undertaken using another reactor structure within the reaction zone provided that one or more gases are delivered to the reaction zone at a sufficiently high temperature to allow the catalytic reaction to proceed. Non-limiting example reactor configurations are illustrated in Figures 1 Ic, I ld.

2. Conversion to Acetic Acid A lower temperature alternative (e.g. 400° C) is to convert the CH4 to acetic acid (as CH4 + CO2 = CH4CO2) or another compound using a reaction zone containing one or more of a particulate material or a membrane, or a coated wall. This approach (based on 90% CH4 conversion and a Pt catalyst) would be expected to change the flue gas (COX + CR4 components) composition from 10.9CC2: 0.OIM CO: 3.01 CH4 to a lower total volume of flue gas containing the molar ratios 8,2CO: 0.3CH4 (assuming 90% CH4 conversion). Discharging the residual flue gas into the atmosphere would reduce the global warming potential of the flue gas from 134 m3 s (CO2equivalent) to 41.55 m3 s' (CO2 equivalent) calculated as 32.4 m3 s' CO2 plus 1188 m3 s' CH4 [with a global warming potential calculated as 21 x 11.9 x {Weight of 1 mole of CH4 (16 gms)/Weight of 1 mole of CO2 (44 gms)}]; (i.e. a >60% reduction in global warming emissions). The CH4CO2 can be removed from the flue gas prior to discharge into the atmosphere. Non-limiting example reactor configurations are illustrated in Figures lIc, lid.

3. Conversion to Vinyl Acetate The CO2 and CH4 in the flue gas can be converted to vinyl acetate using the catalysed reaction route CH4 + CO2 + C21-12 CH3CO2C2H3 at a temperature of around 30° C and a pressure of<0.5 to >15 MPa. Expected CH4 conversion based on a Pt or Pd catalyst is >90%. The C2H2 may be diluted with an inert gas (e.g. N2) or a solvent (e.g. acetone, dimethylformate, toluene, etc.), or mixed with the flue gas prior to entry into the reactor. Discharging the residual flue gas into the atmosphere would reduce the global warming potential of the flue gas from 134 m3 s (CO2equivalent)to 41.55 m3 s' (CO2 equivalent) (i.e. a >60% reduction in global warming emissions). The CH3CO2C2H3 can be removed from the flue gas prior to discharge into the atmosphere. Non-limiting example reactor configurations are illustrated in Figures 1 ic, lId, I Ih, II i, 1 lj. In some embodiments the C2H2 will be replaced by or CXHYOZ, or another organic molecule.

These three non-limiting examples illustrate how the borehole reactor could be used to undertake a number of different reactions which are designed to reduce the global warming potential of a flue gas from a coal powered electricity generation plant.

4. Carbon Sequestration CO2 sequestration in a rock formation (by deep burial) is considered to be a desirable by many governments.

Formation of a Transportable Product A major cost associated with CO2 sequestration is the cost of transporting the gaseous CO2 to an offshore (or onshore) field for sequestration. The field may be located <10 to >1000 km from the power station. The non limiting borehole reactors illustrated in Figures lic, ild, I lh, I Ii, 1 lj can be used to convert the CO2 to a liquid chemical (e.g. CH3CO2) or a fuel. This can reduce the cost of transporting the recovered CO2 to a sequestration location, and can reduce the cost associated with injecting the recovered CO2 into a sequestration reservoir.

Direct Injection The non-limiting borehole reactors illustrated in Figures I ib, lIf can be used to convert the CO2 to a product within the borehole reactor during the sequestration injection process. This sequestration approach can increase the capacity of a CO2 sequestration reservoir by reducing the volume occupied by the sequestered CO2 or by converting the CO2 to a water soluble product, or water miscible liquid product which will dissipate into the rocks pore waters.

A2. Application 2: Desalination of Water The borehole reactor can be used to separate fluids using one or more processes including, but not limited to, microfiltration, nanofiltration, ultrafiltration, reverse osmosis, forward osmosis, fluid separation, membrane distillation. Membranes for fluid separation are made of any suitable material (e.g. Matsuura,1993; Mulder, 1996) Water desalination is an important source of water for drinking and other uses in many areas. Existing reverse osmosis plants use a membrane and the efficiency of the process is controlled by the pressure differential across the membrane. The current technology uses pumps to pressurise the saline water and extracts the fresh water from the low pressure side of the membrane. Existing reverse osmosis plants operate with a low pressure differential across the osmotic membrane (e.g. <8 MPa (typically 0.15 to 0.2 MPa)). This results in large footprint plants with a substantial energy requirement to pressurise the saline water. Matsuura (1993) provides non-limiting examples of membrane manufacturing methods which can be used to construct a membrane to be placed in a borehole (membrane unit (e.g. Figure 8a to 80) to undertake a reverse osmosis or forward osmosis process. Non-limiting examples of suitable membrane material include cellulose acetate, polyamides, polysulphone, polyetherurea, polypiperazineamide and other material. A desalination plant adds chemicals to the feed water to remove biological fouling, scaling or other fouling problems. Membrane fouling is addressed by either removing the borehole membrane unit and replacing the membranes, or by reversing the flow through the membrane. This allows chemicals to be pumped into the borehole to mitigate membrane fouling.

Figure 13a illustrates a non-limiting example of a borehole reactor which is designed to recover water by reverse osmosis or forward osmosis. One or more of the perforated intervals (27, 28, 29) are structured as membrane units containing a reverse osmosis (or forward osmosis) membrane. In this example the reactor is constructed from three casings. In other embodiments the reverse osmosis (or forward osmosis) reactor may be constructed from two casing strings, or a single casing string, or more than 3 casing strings.

A downhole pump (62), or filtration system (62), may be present in the reactor. In Figure 1 3a the inner annulus (5) is used to pump (or suck) desalinated water (or another fluid) to the surface. A reverse osmosis, or forward osmosis system operates by creating a negative pressure across the reverse osmosis or forward osmosis membrane (e.g. the permeable zone, (28)). This can result in different water levels being present in different parts of the reactor (e.g. 60, 61).

The borehole reactor can be located to remove a requirement to pressurise the feed water, and instead uses the natural pressure of the source water in the outer annulus (7 (Figure 1 3a)) and the negative pump suction pressure associated with the fluid recovery pump (62) to create a lower air-water contact (61) in the intermediate annulus than the air water contact present in the outer annulus (60). The air-water contact in the outer annulus may be lower than the air-water contact on the water surface or ground level (2).

This allows a non limiting example borehole reactor (which extends 6 km below the aquifer (or seal level)), to support a 6km water column in the outer annulus (7) and a minimum water column of<1 m in the intermediate annulus (7). This allows a negative pressure of>58 MPa to be created in the borehole reactor and increases the desalination rate associated with a specific membrane surface area. A single reactor of this type has a desalination capacity which is about 290 times greater per unit area of membrane) than a conventional plant operating with a pressure differential of 0.2 MPa across the membrane. Borehole membrane reactors, operated as reverse osmosis or forward osmosis units can contain more than one inner casing (reverse osmosis or forward osmosis membrane unit) operating in parallel. They can be structured as multi-tubular reactors (e.g. Figure l2i).

In the specific case of desalination, the borehole reactor can be constructed as one or more reactors, which are placed largely or wholly in the sea. Figure 13b illustrates four different locations for reverse osmosis or forward osmosis reactor extracting water from the sea. Figure 13b illustrates the seabed (64) and sea surface (63). Reactor (65) is an example of a borehole reactor, which extends below the seabed; Reactor (66) is an example of a borehole reactor, which penetrates the sea, but does not penetrate the seabed. Reactor (67) is an example of a borehole reactor, which penetrates the sea, but not the seabed.

Reactor (68) is an example of a borehole reactor, which is laid on or below the seabed. Reactors which are suspended in the sea (e.g. 66) and are attached to a mobile facility (e.g. a ship) may move. The reactors can be suspended in the water by buoys or another form of fixing or buoyancy aid.

A3. Application 3: Formation of Synthesis Gas from Natural Gas Synthesis gas is catalytically formed as CH4 + a02 cCO2 + dCO + eCH4 + ff12 + gH2O + hC.

Increasing the reaction temperature reduces the proportion of cCO2 + eCH4 in the product gas. Non-limiting example reactor configurations are illustrated in Figures lIe, hg, hlh, lii, I lj. Conventional synthesis gas reactors are operated under isothermal conditions within a narrow temperature range. The borehole reactor, when operated in conjunction with the downstream Fischer Tropsch process can be operated under non-isothermal conditions where the ratio of CO:C02:H2:CH4 varies with time.

A4. Application 4: Formation of Fischer Tropsch Products Borehole reactors can use the Fischer Tropsch reaction to convert a synthesis gas to Fischer Tropsch products.

Non-limiting example reactor configurations are illustrated in Figures 1 Ic, I ld.

A5. Application 5: Reactor for one or more of Partial Oxidation or Carbon Oxide Reforming or Steam Reforming Partial oxidation (CH4 + 0.502 CO + 2H2), carbon oxide reforming (CO2 + CH4 2CO + 2H2) and steam reforming (CH4 + H20 CO + 3H2) are high temperature reactions which are typically undertaken at temperatures in the range 200 -1400 C, typically 400 -1200 C. Steam reforming is endothermic. Carbon oxide reforming is endothermic. Partial oxidation is exotherniic. Each process requires a minimum temperature in order to operate, and the composition of the product synthesis gas may vary with temperature. It is common practice to mix partial oxidation with one or more of steam reforming and carbon oxide reforming, in order to create an essentially exotherniic reaction at the required operating temperature.

A non-limiting example reaction may have three feed gas components C02: CH4 and 02. Use of a Ni/Al203 catalyst with a space velocity of 8000 m3 CH4 hr1 m catalyst at 800 C will result in the product gas composition varying as a function of the CH4:02 ratio and CH4:C02 ratio in the reaction zone. These gases may be mixed prior to entering the reactor or may be mixed within the reactor. The nonlimiting example catalyst can be formed by impregnating an alumina support (e.g. I -2 mm particle size) with a solution of Ni(N03)2. The catalyst is activated (reduced) by flowing H2 at (800 C) or CO or NH3 through the catalyst at an elevated temperature (e.g. <400 ->800 C). Activation can be undertaken after the catalyst is placed in the reactor. The catalyst contains <1% and >5% Ni (by weight). The expected product gas composition for a feed gas of I CH4: 1C02:0.302 = I CO: 0.08 CH4: 0.34 C02: 1.21 H2. The expected dry product gas composition for a feed gas of I CH4:0.3 C02:0.6 02 CO: 0.01 CH4: 0.33 C02:1.85 112.

In this process the catalyst is normally either changed periodically or left in the reactor for the reactor life. A gas field producing 10 MMscf/d gas composed of 77% methane and 23% C02, will require about 3.8-4.6 MMscf7d 02 to produce a synthesis gas with a C0:H2 ratio of 1.85, with the bulk of the methane converted in accordance with the reactions CR4 + 0.502 CO + 2H2, IHR(298 KY -35.7kJ moF1; and CO2 + CR4 = 2C0 + 2H2, IHR(29g K) 247.3 kJ mo1'.

Some of the CH4 will be converted in accordance with the exothermic reaction:-CH4 202==C02+2H20 The same catalyst operated on a gas field producing 10 MMscf7d gas composed of 100% methane will require about 5 MMscf/d 02 to produce about 30 MMsclId synthesis gas with a C0:H2 ratio of 2.0 and will have a net exothermic reaction. The reactor, or reactors, will contain around 1.5 m3 catalyst (operating at a GHSV of 8000). A non-limiting example reactor unit could be constructed from 2 or more borehole reactors operating in parallel, where each borehole reactor is constructed in accordance with Figure 1 lj. Each reactor acts as a balanced flue where the heat contained in the product gases is used to heat the feed gases within the reactor before they arrive in the reaction zone. The reactants (O and CH4) are mixed within the catalyst bed.

Thus the present invention comprises a combination of features and advantages that provide it with flexibility, allow it to be constructed to accommodate a wide range of feed stocks and operating conditions and allow it to produce a range of products.

These and various other characteristics and advantages of the present invention will be readily apparent to those skilled in the art upon reading the detailed description of the preferred embodiments of the invention and by referring to the accompanying figures. It is to be understood that the present invention is not limited by the examples set forth which have been provided merely to demonstrate operability.

Modifications and variations of the process, methods, catalysts and apparatus described herein will be obvious to those skilled in the art from the foregoing detailed descriptions. Such modifications and variations are intended to come within the scope of the attached claims.