CA2779238A1 - Selective leach recovery of oil (and asphaltene) from oil sands and like materials - Google Patents
Selective leach recovery of oil (and asphaltene) from oil sands and like materials Download PDFInfo
- Publication number
- CA2779238A1 CA2779238A1 CA2779238A CA2779238A CA2779238A1 CA 2779238 A1 CA2779238 A1 CA 2779238A1 CA 2779238 A CA2779238 A CA 2779238A CA 2779238 A CA2779238 A CA 2779238A CA 2779238 A1 CA2779238 A1 CA 2779238A1
- Authority
- CA
- Canada
- Prior art keywords
- oil
- leachant
- leachate
- precipitant
- asphaltenes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
- C10G1/04—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal by extraction
- C10G1/045—Separation of insoluble materials
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G21/00—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents
- C10G21/003—Solvent de-asphalting
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G21/00—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents
- C10G21/06—Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents characterised by the solvent used
- C10G21/12—Organic compounds only
- C10G21/16—Oxygen-containing compounds
Abstract
Oil sands and like host materials containing asphaltenes (usually as bitumen) are treated with a combined leachant plus-precipitant selected to leach the oil into a leachate while concurrently precipitating asphaltenes. This has been found to enable the leachate to maintain a desired flow rate through the host materials. Most suitably the leachant is a selected monoterpene and the precipitant is a selected alcohol. Selected hydrocarbons were found to be less effective as precipitants, but would suffice in some situations. Recovered leachate is treated to remove particulates and to separate both leachant and precipitant for recycle. Where asphaltene recovery is desired, entrained asphaltene particles are separated from the leachate and residual asphaltene particles recovered from the host material. The remaining leached crude oil is very suitable for pipelining.
Description
SELECTIVE LEACH RECOVERY OF OIL (AND ASPHALTENE) FROM OIL SANDS AND LIKE MATERIALS
FIELD OF THE INVENTION
[0001] The invention relates to an oil recovery process employing in situ leach mining (ISLM) (or mining plus passing mined material to a leaching unit), for the selective recovery of crude oil from hosts including but not limited to oil sand, carbonate rock, sandstone and shale deposits and soil for remediation.
BACKGROUND OF THE INVENTION AND PRIOR ART
FIELD OF THE INVENTION
[0001] The invention relates to an oil recovery process employing in situ leach mining (ISLM) (or mining plus passing mined material to a leaching unit), for the selective recovery of crude oil from hosts including but not limited to oil sand, carbonate rock, sandstone and shale deposits and soil for remediation.
BACKGROUND OF THE INVENTION AND PRIOR ART
[0002] Oil is the principal form of energy in the world. Its origin is popularly attributed to decayed organic matter formed in the Carboniferous period. Oil is required for locomotion, (automobiles, ships, aircraft,) heating, lubrication and manufacture of organic-based materials.
Its principal source is as natural pools chiefly in Saudi Arabia, Iran, Iraq, Nigeria, Algeria, beneath portions of the North Sea, Gulf of Mexico, off-shore Brazil and to a lesser extent in many other localities from which it is recovered by pumping. Oil also occurs in secondary deposits as heavy oil either mixed with sand (e.g. Alberta Canada, Venezuela, Trinidad and USA) or contained in carbonate rock (e.g. Canada, Kuwait neutral zone), or sandstone (e.g.
USA) or wide-spread internationally in shales (e.g. USA).
Its principal source is as natural pools chiefly in Saudi Arabia, Iran, Iraq, Nigeria, Algeria, beneath portions of the North Sea, Gulf of Mexico, off-shore Brazil and to a lesser extent in many other localities from which it is recovered by pumping. Oil also occurs in secondary deposits as heavy oil either mixed with sand (e.g. Alberta Canada, Venezuela, Trinidad and USA) or contained in carbonate rock (e.g. Canada, Kuwait neutral zone), or sandstone (e.g.
USA) or wide-spread internationally in shales (e.g. USA).
[0003] Heavy oil has a specific gravity rating according to the American Petroleum Industry (API) designation, from 0 to about 25 . It is comparatively more difficult and therefore expensive to recover heavy oil for industrial use from foregoing secondary deposits rather than from ones that can be pumped. Moreover with one notable exception, secondary deposits are not very large. The exception is the Athabaska oil sands deposits in the provinces of Alberta and Saskatchewan.
[0004] The Athabaska oil deposits consist of a number of same in oil sand plus one in carbonate rocks. The main deposit, the Athabaska (after which the deposits are collectively named), has three smaller satellites, the Peace River, Cold Lake and Lloydminster along with lesser such deposits. They form a north westerly belt across the north central portion of Alberta extending from about 100 kms (62 miles) north of the town of Fort McMurray southward to within 75 km (47 miles) north of the city of Edmonton. The Athabaska deposit is the largest member being up to 250 km wide by 450 km long (155 miles by 280 miles). The three other principal members are about 20% of its size and the remaining members much smaller.
[00051 There are also vast amounts of heavy oil (about 26% of the amount estimated in the oil sands reserves) in carbonate rocks beneath the Alberta oil sands. These latter deposits have about 7% - 40% porosity and 100 to 10,000 mDarcies (mD) permeability. They and carbonate rock deposits together are estimated to contain 2.15 x 1011 m3 of bitumen roughly equal to 1.51x1011 m3 of oil. This amount is equivalent to about one trillion (1x1012) US barrels (USb) of heavy oil which is the estimate for the Saudi oil deposit. The Athabaska deposits may be larger than implied above as they are not yet defmed. They and the Saudi deposits represent the two largest individual accumulations of oil in the world.
[0006] The Athabaska oil sands deposits consist of a mixture of about 1% to 15% averaging 8%
bitumen (congealed heavy oil) plus minor fme clay (silt) and water in high porosity (28% - 32%) quartz arenites varying to arkosic sands of Cretaceous age. Their permeability is about 35 D.
They form flat lying sheet-like zones up to about 20m (66ft) thick across the area. The zones vary in vertical depths below surface up to about 400m (1,300ft) depending on the overlying overburden thickness and are flanked above and below by sandstone-shales and limestone beds respectively. The overburden consists of muskeg, sand, gravel and clay (largely unsuitable for farming).
100071 Bitumen is a tar like substance comprising various types of petroleum products ranging from asphaltenes to light petroleum with approximate parameters and composition, according to the API, of specific gravity = 8 -14 , C = 83.2%, H = 10.4%, 0 = 0.94%, N =
0.36% and S
4.8%. Currently the bitumen is initially recovered from the host deposit and then either sold as is or up-graded by distillation plus reduction of S and N and addition of H to become more valuable types of petroleum products. Raw bitumen is worth about 75% of the quoted price of Saudi oil. Accordingly bitumen is initially upgraded into two fractions: one containing about 30% of the bitumen with the heavier hydrocarbons including asphaltenes and the remainder being lighter hydrocarbons similar to Saudi crude. The fractions are refined to more valuable products.
[0008] As used herein, the "oil" in oil sands and other host materials is intended to comprise various petroleum oils particularly heavy oil and bitumen which include asphaltenes. Normally these recovered oils are subject to various fractionations and hydrocracking to derive desired useful products.
[00091 Further background and prior art are described in related United States Application No.
12/381,918 filed March 18, 2009.
[0010] Various processes for recovering oil from oil sands and the like by solvent extraction and in situ pooling and leaching have been studied particularly in the years from about 1970 to 1985.
Hot water, steam and petroleum-based solvents and diluents have been tried without real success.
Apparently no significant commercial operation of this type has existed: it is understood that high solvent losses, low overall recoveries and other operating problems as well as competitive pressures, have kept such operations from being cost effective. Typical references include: US
Patent Nos. 3,858,654; 3,881,550; 3,929,193; 4,474,238; 4,510,997 and GB
Patent No.
2,136,034.
[0011] Kenchington et al. in "Energy Sources", Vol. 5, No. 4, 1981, pp. 317-338 summarizes cost parameters for solvent extraction of mined oil sands using petroleum cuts or blends of C6-C9 aliphatics and aromatics. Brief mention is made on p. 318 of in situ processes for oil sands too deep to mine in which a steam or flame front is generated to drive distilled and cracked product to a recovery well. No direct ISLM technique is mentioned.
[00121 As described in United States Patent Application No. 12/381,918 selected plant-derived non-aqueous liquids are unexpectedly advantageous solvents for oil extraction including in situ leach mining of oil-bearing deposits. In particular monoterpenes having the formula C10H16 have been found very suitable for e.g. in situ leaching of deposits having heavy oils ¨ bitumen ¨
kerogen asphaltenes therein. These monoterpenes are a renewable resource and are by-products of citrus fruit processing and wood harvesting and are biodegradable.
[0013] The use of a biodegradable non-toxic, non-carcinogenic, plant-derived solvents lead to degradation of residual amounts of solvent left following its application and enables environmentally-sustainable resource development. Especially in the case of remediation of contaminated sites, the residual monoterpene solvent after in situ leaching is believed to enhance the overall biodegradation of solvent - plus-oil remaining at the site, and expedite remediation.
This is not feasible with non-renewable petroleum-based solvents.
[0014] Selected monoterpenes include:
Item Boiling Point (range) Flash Point Limonene (d or 1) 176-177 C
Dipentene (d + 1) 175-176 C 45 C
p-Pinene 164-169 C 47 C
a-, P-Terpinene 180-183 C
[0015] Monoterpene leachants preferably are selected to comprise at least one of limonene (d or 1), dipentene, 13-pinene and a- and I3-terpinene.
[0016] Preferred monoterpenes include d-limonene, 1-limonene and dipentene.
[0017] a-pinene has a boiling point of 156-160 C and flash point of 32 C and would require appropriate handling precautions: it would be more suitable for use in winter conditions.
[0018] It has been found that these monoterpenes are able to provide leachates of pumpable viscosities when present in amounts as low as about 20% by volume of the leachate. They are able also to allow and withstand repeated separation and recycling steps.
[0019] Monoterpenes such as limonene and dipentene are much less toxic than mineral spirits (and toluene), are non-caustic, non-reactive to metal surfaces, non-carcinogenic or mutagenic and are readily biodegradable. Due to their flash points these selected monoterpenes should be handled with appropriate care. They are currently regulated as volatile organic compounds (VOC), however their use with recycling should not result in the release into the environment of any more materials than would occur naturally.
[0020] D-limonene is listed as a non-toxic chemical in the Toxic Substances Control Act (TSCA). It is not listed within the Species At Risk Act, Title III compound and is not regulated by the Clean Air Act. The product is also classified as a food additive and has been granted the FDA's GRAS (Generally Recognized As Safe) status. The Environmental Protection Agency (EPA) regulates the use of d-limonene when insecticidal properties are claimed. It coagulates if exposed to sunlight but this can be prevented by the addition of a small amount of an antioxidant e.g. butylated-hydroxy-toluene (BHT) which is also used for human consumption.
Other antioxidants such as phenyl-beta-naphthamine and di-tert-butyl-para-cresol may be used. D-limonene is manufactured inter alia by Florida Chemical Company Inc, 351 Winter Haven Blvd, Winter Haven FL 33881-9432, USA, tel. 863.284.8493. It is available through major distributors e.g. EWR International Inc, 1310 Goshen Parkway, West Chester PA, 19380, USA, tel 619.431.1700. It is understood to be available also from producers in Brazil and Asia inter alia.
[0021] Dipentene is available, similarly and compared to d-limonene, is more resistant to oxidation.
[0022] As outlined in United States Patent Application No. 12/381,918, it has been found that the porosity and permeability of the Athabaska oil sands deposits and their underlying oil bearing carbonate rocks plus the oil bearing sandstones in the USA, as shown in the following table, renders them excellent candidates for ISLM according to this invention. In addition the necessary permeability to enable ISLM may be created in formations such as shale deposits by hydrofracturing them with the addition of particles such as aluminum oxide acting as propants to hold fissures open and thus allow access to the oil deposits, as known to those skilled in the art.
Item porosity permeability Athabasca oil sands About 35 % About 35 D
Athabasca carbonate rocks About 20 % 100-104 mD
USA sandstones About 16%-22% 100mD¨ 600mD
[0023] In order to perform in situ leaching (ISL), the target deposit permeability should preferably be at least about 100mD.
[0024] Bitumens and particularly the asphaltenes therein are the components of the oil in oil sands and the like, which are most difficult to dissolve and maintain in solution. Toluene is known to be a very good solvent for bitumen including asphaltenes. In comparison tests, limonene was found to be a good solvent for bitumen and shale oils (approaching toluene in effectiveness) and able to keep the asphaltenes from precipitating. Naphtha was found unable to prevent the asphaltenes from precipitating forming blocks preventing solution travel during pipeline transportation (in effect acting as asphaltene precipitant).
SUMMARY OF THE INVENTION
[0025] In the course of further testing (flowing from United States Patent Application No.
12/381,918) it was found that in many cases, particularly where longer ISLM
runs and/or reduced porosity occurred, there were significant increases in viscosity and back pressure leading to low efficiencies and poor recoveries. The cause was found to be asphaltene build-up in the leachate. It was discovered that adding selected precipitants for asphaltenes to the leachant led to particulates of asphaltenes being formed in situ with only the very fine ones moving with the leachate and with no significant reduction in leachate flow rate over time.
[0026] The most effective asphaltene precipitants for maintaining leachate flow rates were found to be selected alcohols e.g. within the C2 to Clo range. While certain hydrocarbons function as asphaltene precipitants they have been found to be less effective in this leachate context compared to e.g. isopropanol. While less effective than selected alcohols, they are considered able to maintain sufficient flow rates (leachate) to be operative (see Example 2).
[0027] Preferably the process of the invention incorporates a leachant, e.g. d-limonene, which contains a precipitant, e.g. isopropanol, to selectively dissolve the heavy oil from bitumen, while at the same time precipitating or preventing the asphaltenes from dissolving.
Using ISLM
methods the heavy oil is recovered along with fine particulate asphaltene, clays and silts. The asphaltene, clay and silt particles, and any groundwater present, are removed by centrifuge for deposition or sale. The leachant-precipitant is removed from the heavy oil e.g. by vacuum distillation and recycling back into the well-field forming a closed loop process for further use.
[0028] The process of the invention incorporates a precipitant, e.g. a selected alcohol or hydrocarbon, used in conjunction with the leachant to prevent asphaltene from increasing the viscosity of the leachate in the site or oil-field. This in effect eases flow through within a well-field while conducting ISLM or at a processing site.
[0029] A particular benefit of the process would be to approximately double the monetary value of the oil sands deposits for which it is used. This is because it can recover over 95% of the contained oil compared to about 50% or less by current technology. It also should be able to advantageously recover the oil by-passed by steam-assisted gravity drainage (SAGD) and open-pit mining (OPM) and contained in the sandstone and carbonate rocks that is considered to be uneconomic by existing technology. Test results also disclose the ability of selected monoterpenes e.g. d-limonene to leach oil from a shale deposit.
[0030] In one embodiment the oil sands or similar host materials are in their original deposit location and are subject to in situ leach mining using the selected leachant and the loaded leachate removed and passed to a processing site.
[0031] In some cases the host materials are open-pit mined and transported to a processing site for steps upgrading.
[0032] It is also intended that the host material may be oil and asphaltene-contaminated soil (including sub-soil) that is treated in situ or off-site for the purpose of remediation.
[0033] The process (as defined herein) broadly covers leaching bitumen or oil from oil sands and like host materials containing asphaltenes with a selected leachant which also leaches asphaltenes with the improvement comprising including in the leachant an additive selected to precipitate asphaltenes, the additive being present in an amount sufficient to maintain an operative leachate flow rate through the host materials throughout the leaching process.
[0034] The precipitant additive preferably is a selected alcohol (as described herein) but may be a hydrocarbon selected from pentane, heptane and a selected naphtha. When the additive is a naphtha, it may be retained in the recovered oil as a thinner for pipelining.
The additive may be a combination of a selected alcohol with a selected naphtha, and only the alcohol is recovered for recycling before pipelining.
[0035] The invention includes a leachant composition comprising monoterpene leachant and an additive selected to precipitate asphaltenes; as well as the resulting leachate including leached oil from which asphaltenes have been precipitated. More specifically the invention includes leachate compositions comprising selected alcohol precipitant for asphaltenes, monoterpene leachant and oil leached from oil- and mineral-containing host materials.
[0036] More preferably the invention includes a process of separating oil from oil sands and similar oil- and mineral-containing host materials wherein asphaltenes are present comprising contacting the host materials with a combined leachant-plus-precipitant in which the leachant is a selected monoterpene and the precipitant is an alcohol selected to precipitate asphaltenes sufficiently to enable desired leachate flow rates; removing the oil-loaded leachate from the host materials; separating entrained asphaltene, silt and clay particles from the leachate; separating the leachant and precipitant from the leachate for recycle; and recovering the separated oil and optionally separated asphaltene particles for further treatment.
[0037] The alcohol precipitant preferably is at least one selected from saturated aliphatic and alicyclic mono- and di-hydric alcohols having from 2 to 10 carbon atoms.
[0038] More preferably the alcohol is selected from the group isopropanol, propylene glycol, pentanol, cyclohexanol and decanol.
[0039] Optionally the process may include a subsequent wash of the leached host material with a selected aqueous liquid to recover residual asphaltene particles from the host materials, and the combined recovered asphaltene particles treated to isolate useful components.
[0040] The alcohol precipitant is used in selective effective amounts within the range from about 30 to about 90 % by volume of the monoterpene leachant. A preferred range for isopropanol is about 50 to 70% by volume. Usually the amounts are chosen to result in adequate leachate flow rates in the host material.
BRIEF DESCRIPTION OF DRAWINGS
[0041] Figure 1 depicts the streamline flow leaching pattern of a regular five spot well system with corner guard wells. It illustrates one general technique of the method that would be employed to perform ISLM.
[0042] Figure 2 depicts a wellfield consisting of four adjoining regular five spot well systems. It illustrates the general layout of a wellfield to perform ISLM. The size of the well systems and therefore the resulting wellfield and the resulting oil production, are based on the relevant hydrologic parameters understood by those skilled in the art.
[0043] Figure 3 depicts a conceptual injection/recovery straddle packer system for use in wells.
In one embodiment packers are the heart of each well system enabling solution delivery to and recovery from specific parts of the area to be leached.
[0044] Figure 4 is a conceptual depiction of a process flowsheet to recover oil (and asphaltene) contained in oil sands, carbonate rock (limestone), sandstone or shale oil deposits.
[0045] Figure 5 depicts in cross-section a conceptual ISLM system to recover oil from an oil sands and/or underlying carbonate rock with oil deposit containing asphaltenes.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS
[0046] The process usually employs two steps to selectively recover crude oil and asphaltene directly from bitumen in oil sands deposits. Associated particles of asphaltene, clay and silt can be selectively recovered from the leachate e.g. by use of a centrifuge,and the leachant and precipitant can be removed from the remaining crude oil e.g. by use of vacuum distillation. The remaining oil can be transmitted by pipeline, to a refinery, if desired adding condensate for thinning. The process flowsheet may for example consist of one centrifuge, a vacuum distillation unit and mixer to accomplish selective recovery of asphaltene, and oil (which latter may then be mixed with naphtha (or condensate) for thinning to enable easier pipeline transmission. The leachant-precipitant mixture is recovered for re-use, and asphaltene plus clay and silt particles are discharged; or the asphaltene is separated and recovered for use or treatment.
[0047] ISLM performed on sand, carbonate rock, sandstone or shale oil deposits to recover oil entails injecting leachant through the deposit to dissolve the oil into a leachate that is then treated to separate the oil from the leachant and recycle leachant for further leaching. Figure 1 illustrates the basic principle of ISLM. It depicts the computer generated stream lines of a solution flowing from an injection to recovery points in a permeable medium. The leachant is injected into the deposit via pipes inserted in the deposit according to a wellfield design based on hydrologic modeling studies and ISLM tests conducted on the deposit. The leachate is treated to recover the oil for sale, remove the leachant for re-use and discard associated water if necessary.
[0048] The well system shown in Figure 1 consists of five vertical wells installed in a square pattern in a geologic formation of suitable porosity and pernieability. One of the wells is located in the center of the pattern to inject solution (leachant) to dissolve or target oils thereby forming a leachate. A vertical well is also located at each corner of the pattern to conduct pumping forming sinks to recover the leachate. The leachate is discharged to the plant for treatment.
[0049] Guard wells (if required) surround the well system according to modeling studies. Their purpose is to recover groundwater to reduce its ability to dilute recovered leachate. The water they collect is discharged at a suitable distant site.
[0050] The stream flow lines depict the paths of individual segments of the leachant moving toward a recovery well. The segments outside of the well system boundary will leach the relevant area traversed and attract ground water if present. Potential leachate excursion in the course of ISLM recovery (i.e. wandering beyond the well system) is regarded as unimportant because of its organic similarity to and therefore compatibility with its environment particularly due to the biodegradable leachant selected.
[0051] An inverted well system involves injection performed by the four peripheral wells and recovery by the central well. Its choice as well as that of either a regular or inverted polygonal well system (providing more recovery wells to offer dilution abatement and leaching advantages) is indicated by modeling.
[0052] The first steps of the ISLM process are to define the geologic and hydrologic parameters of the oil deposit to perform modeling studies. Parameters include (a) extent/variation in bitumen concentration and contained oil and (b) porosity, pemteability, solution travel time between injection and recovery wells, groundwater amount and flow direction and size/distribution of fractures that could affect leaching. This information enables the design of a wellfield to yield the desired rate of oil recovery.
[0053] It may be necessary to increase the permeability of a deposit to enable satisfactory ISLM
or to strengthen the walls of the installed wells to prevent caving or to plug channels in the deposit or surrounding formation that act as short circuits preventing proper leachant delivery.
These tasks can be performed by people skilled in the art. The first can be achieved by hydro-fracturing the deposit (i.e. injecting high pressure water with the addition of aluminum oxide particles to force and prop open fractures necessary for the purpose).
Strengthening well hole walls is accomplished by electrical induration. Preventing potential short circuit channels entails mapping their routes by water injection temperature sensing and then plugging them at selected locations by injecting cement grout.
[0054] Injection and recovery wells are purpose drilled vertical holes about 15cm (6 in) outside diameter (OD) according to the selected wellfield pattern. They extend from ground surface to the bottom of the portion of the deposit selected for ISLM. They are cased from surface into the top of the deposit to strengthen the well mouth.
[0055] For example, in Figure 2, leachant is supplied to the wellfield from the treatment plant via a single pipe e.g. consisting of high density PVC, lying on ground surface and usually extending to a pump house. From there leachant is distributed by individual pipes (e.g. PVC) to the respective injection well heads where a high pressure pump injects it into the host material.
Sensors installed in the individual pipes record relevant parameters including speed, volume and chemistry. This information is relayed to the control centre in the plant to guide changes in the leachant delivery protocol and to forecast estimated oil production.
Continuous solution movement in pipelines prevents freezing. In the event of plant delays e.g. in winter, solutions can be recycled through the deposit until operations resume. Recovery well pumps usually send their leachate to the pump house where it is combined into a single pipe to the plant.
[0056] The main concern of ISLM is to insure efficient delivery of leachant through the deposit to provide sweep efficiency and to prevent loss of leachate. In the circumstances the latter is not a serious issue because of the extensive expanse of oil host surrounding the area being mined identical in nature to the leachate components plus the absence of toxic chemicals being used.
[0057] In one aspect each well is fitted with a straddle packer system e.g. as depicted and described in Figure 3 consisting of a pipe e.g. stainless steel, extending from surface to the bottom of the wellbore. It is perforated along its portion traversing the target extraction section to enable injection or recovery of leach solutions. The pipe is sized for the injection pressure and amount of solution to be delivered. It has rubber packer sleeves above and below the perforated sections that can be hydraulically expanded to form a 20,000 psi seal with the well bore to prevent upward migration of solutions. Packer systems intended to recover rather than inject solutions are fitted with internal submersible pumps rather than external injection pumps.
[0058] Well holes are drilled to a depth slightly beyond that of the oil matrix section to undergo leaching and to accommodate the packer system e.g. as in Figure 3. A metal casing is inserted into the top of the well hole to a depth slightly deeper than the overburden to stabilize the well entrance. A straddle packer system is installed in the well hole to sequester the section to be leached and to deliver leachant and recover leachate.
[0059] The packer preferably consists of a sectional pipe e.g. 316 stainless steel, extending from the top to bottom of the wellbore. The central service portion covers the section of the well intended for leaching. Its OD is slightly less than the inside diameter (ID) of the wellbore and is perforated to enable injection or recovery of solutions. It may be fitted with two adjustable double rubber sleeves (packers) one at each end of the section. The sleeves can be compressed longitudinally by hydraulic rams to expand laterally forming a 20,000 psi seal with the wellbore to prevent vertical migration of fluids thereby sequestering (i.e. packing off) the section to be leached.
[0060] A shorter narrower delivery pipe is attached to the upper end of the service pipe to convey leachant to or leachate from the packer service pipe section. It also houses the hydraulic fluid line to the rams and the electrical supply cord to the submersible pump.
[0061] The packer is fitted with a submersible electric pump if it is intended to recover leachate rather than inject leachant. The pump exit is attached to the bottom of the service pipe to discharge leachate through it to surface where it is conveyed to the plant.
[0062] As examples for ISLM there are two standard ISLM well system arrays described herein with differing attributes designed to inject and recover solutions. A regular five spot well system consists of a square pattern with a vertical well at the centre of the square to inject leachant to dissolve intervening material plus a vertical well at each corner of the pattern to recover resulting leachate. An inverted five spot well system injects leachant at the corner wells and recovers leachate from the central well. A series of adjoining well systems constitutes a wellfield. The addition of guard wells with recovery pumps appropriately placed around a well system or wellfield perimeter discharging such water at a suitable distant site can greatly assist in reducing groundwater dilution of recovered leachate. The optimum design of a well system as to shape (square or polygonal), regular or inverted and guardwell locations, to maximize sweep efficiency is based on ISLM field tests and modeling studies.
[0063] In practice, a wellfield necessary to recover the target amount of oil is installed in the oil-bearing deposit according to a pattern based on modeling studies and hydrologic tests. Leach solution (leachant) is injected through the deposit via some of the wells to selectively dissolve the calculated amount of oil. Resulting pregnant solution (oil/monoterpene leachate) is extracted through adjacent wells and pumped to the treatment plant where the leachant, the dissolved oil and any associated water are recovered selectively.
[0064] An ISLM well-field to recover oil from a deposit is conceptually depicted in Figure 2. It comprises four adjoining regular five spot well systems with central wells injecting leachant plus peripheral pumping wells that recover the leachate. A treatment system selectively recovers the resulting monoterpene-oil leachate by rejecting its associated groundwater.
[0065] Because of the differing oil deposits (i.e. in sand or carbonate rocks), the straddle packer that would be employed (e.g. in Figure 3) must be adjusted to suit the material being leached. If the deposits have different permeabilities they cannot be leached together because the one with higher permeability will short circuit the other. Consequently the lower permeability zone must be increased by hydrofracturing to equal the adjoining permeability or both deposits leached separately.
[0066] Referring to the blow up in Figure 5 showing the sand grains microscopic examination has revealed that such grains (plus their associated bitumen patches) are surrounded by a thin layer of water that evidently enables leachant plus precipitant to migrate along the hydrophilic surfaces of sand and to reach bitumen which facilitates the leachate phase-particle separation in situ and also in subsequent processing. (Microscopic Structure Of Athabaska Oil Sands, Koichi Takemura, Canadian Journal of Chemical Engineering, vol. 60, August 1982).
[0067] The process has the potential of recovering oil resources from low grade or small deposits in contrast to other processes that would not be economical for same. It is versatile and capable of high recovery and output well beyond that by conventional technologies currently in use to recover oil and/or bitumen from the foregoing deposit types. Moreover it does so in a more advantageous manner. It can achieve oil recovery at comparatively lower costs with reduced environmental impact because it does not employ steam, can avoid mining operations that create substantial ground disturbance or waste piles and avoids creating contaminated or toxic discharges.
[0068] One example of ISLM entails installing a series of vertical pipes according to a selected certain pattern (wellfield), into a geological formation of suitable porosity and permeability to permit a leachant- precipitant to be pumped through the formation via some of the (injection) pipes to dissolve target constituents. The resulting leachate is recovered to surface for treatment via the remaining (recovery) pipes.
[0069] This technique employing selected monoterpenes would aim to recover oil/bitumen almost completely from host deposits at comparatively low cost and virtually no environmental impact. Groundwater dilution of the oil/bitumen can be prevented by appropriate wellfield design employing guard wells and/or electric fences. Extracted groundwater may be treated to meet statutory regulations and re-injected into the earth at a selected site or otherwise suitably disposed of [0070] The permeability of a deposit can be increased if necessary to perform ISLM by means well known to those skilled in the art. A standard method is to adopt the procedure employed by water well drillers to hydrofracture the deposit by injecting high pressure water at up to 20,000 psi or more to separate portions of the deposit and adding a propant such as fine particles of aluminum oxide to keep the separated portions apart. The limonene or other monoterpene leachant can be recovered from the oil/bitumen leachate e.g. by vacuum distillation. It is recycled for further leaching and the oil/bitumen/asphaltene components recovered for sale or refining to more valuable products.
Estimated oil recovery from hypothetical block of oil sands [0071] The average thickness of various oil sands layers in Alberta is reported to be about 20m (i.e. about 66ft). Assuming the permeability of such oil sand of about 35 Darcies a wellfield area 600ft square over half that depth of oil sand would represent an oil sands block amounting to 600x600x33 ft = 12x106 ft3 and that is easily within the capability of ISLM in one day given the permeability of the target material.
[0072] Assuming average bitumen content = 8% therefore the contained bitumen in the zone =
10x105 ft3. At 5.62 ft3 bitumen/US bbl therefore this represents 1.78 x105 US
bbl/d of bitumen.
Assuming 70% bitumen = oil (balance is asphaltene) the foregoing = 1.246x105 US bbl/d of oil =
455 x 105 US bbl/yr of oil and @ $50/b = $2 x 109/yr.
[0073] The foregoing ISLM estimation demonstrates the potential value of oil recovery from oil sands/carbonate oil bearing rock or oil shales that can be achieved.
[0074] Oil from the foregoing sources is regarded as heavy oil. Apart from oil sands its normal rate of production by North American producers is less than about 100,000 US
bbl/d. Two of the current fourteen Athabaska oil sands operators produce about 200,000 US bbl/d and are scheduled to increase output to about 350,000 US bbl/d. As these calculations indicate, an ISLM
project involving a well-field 183 m2 (600ft2) x 10m (33ft) deep could produce about 125,000 US bbl/d of oil based on conservative figures. Expanding this output could be possible, by appropriate extended use of the present invention.
[0075] In many cases the recovered asphaltenes contain valuable components, in particular trace metals and rare earths (oxides) whose value justifies recovery treatment. For example it is known that Alberta oil sand asphaltenes contain vanadium oxide usually in amounts to justify recovery.
EXAMPLES
[0076] The following examples are meant to illustrate but not limit the invention.
[0077] Laboratory tests have indicated that the addition of monoterpene leachant in excess of the volume of the pore space will readily leach bitumen from oil sands in an open vessel. Scalable tests (laboratory tests that can be scaled up to full field conditions) indicate that plugging occurs when flow through of leachant is attempted under lower porosity confined conditions. It was suspected that the rate of change in viscosity by the asphaltenes caused the observed blockage and pressure increase. Use of push-pull ISLM methods alleviated the problem but increased the time required to leach an oil sand well-field. However, when the asphaltene was absent from the leachate (by precipitation), the viscosity problem was solved and the fine asphaltene could be removed easily with the silt and clays by flow-through ISLM methods. This was achieved by introducing a selected asphaltene precipitant, e.g. isopropanol, to the d-limonene leachant as described herein.
[0078] In order to prove this method, gravity leaching tests (gradient = 1) were performed on similar samples of oil sand, packed to represent reservoir conditions, in vertical glass tubing. The leachant in the first test was 100% d-limonene, while in the second test a selected precipitant was added to the leachant to form a 50:50 mix by volume of d-limonene and isopropanol. In the first test, leachate recovery slowed to a trickle by the second pore volume of leachant; due to pore plugging caused by viscosity and pressure increases. In the second test the leachate mixture was recoverable at a constant free flow rate. The leachate from this second test consisted of a mixture of crude oil, d-limonene, isopropanol as a single phase, and particles of asphaltene, clay and silt.
D-limonene dissolution of bitumen [0079] Laboratory tests disclosed that the ratio of d-limonene to bitumen for the leachate to provide highest flow rate was about 54gm bitumen/liter of d-limonene. One liter of limonene is able to render pumpable up to about 40g oil from oil sands. Isopropanol precipitation of asphaltene. Laboratory testing indicated that isopropanol when introduced to a d-limonene leachate loaded with dissolved bitumen will, when used in the same volumes as naphtha, pentane and heptane, precipitate more asphaltene from the leachate than the latter hydrocarbons.
Selective leaching of bitumen using a d-limonene/isopropanol leach [0080] A leachant consisting of 50% d-limonene and 50% isopropanol was found to leach bitumen while at the same time causing the precipitation (separation) of the asphaltenes. This facilitates flow within the well-field so that ISLM flow-through methods can be feasible. These methods are much faster and more efficient than are the push-pull methods that must be considered when using a 100% d-limonene leach.
[0081] Isolation of the asphaltenes using the above method expedites pre-pipeline upgrading by enabling removal of entrained asphaltenes, silts and clay particles e.g. by use of a dynamic centrifuge as opposed to more time consuming chemical methods. The isolation and recycling of the d-limonene and the isopropanol can be achieved by use of vacuum distillation; leaving the de-asphaltened crude oil ready for shipment to refinery by pipeline. In the case where the oil is too thick, selected condensate (naphtha) can be added as a thinner (see Fig.
4).
[0082] One preferred ISLM process is to carry out in situ leaching utilizing a mixed leachant consisting of d-limonene as a solvent and isopropanol as a precipitant and employing a well-field consisting of adjoining regular or inverted five spot well systems with guard wells linked together to recover oil/ and asphaltene from either an oil sands, carbonate rock or a sandstone deposit as in Fig. 1 plus Fig. 4. Recovered ground water can be recycled in situ to wash out residual asphaltene particles.
[00051 There are also vast amounts of heavy oil (about 26% of the amount estimated in the oil sands reserves) in carbonate rocks beneath the Alberta oil sands. These latter deposits have about 7% - 40% porosity and 100 to 10,000 mDarcies (mD) permeability. They and carbonate rock deposits together are estimated to contain 2.15 x 1011 m3 of bitumen roughly equal to 1.51x1011 m3 of oil. This amount is equivalent to about one trillion (1x1012) US barrels (USb) of heavy oil which is the estimate for the Saudi oil deposit. The Athabaska deposits may be larger than implied above as they are not yet defmed. They and the Saudi deposits represent the two largest individual accumulations of oil in the world.
[0006] The Athabaska oil sands deposits consist of a mixture of about 1% to 15% averaging 8%
bitumen (congealed heavy oil) plus minor fme clay (silt) and water in high porosity (28% - 32%) quartz arenites varying to arkosic sands of Cretaceous age. Their permeability is about 35 D.
They form flat lying sheet-like zones up to about 20m (66ft) thick across the area. The zones vary in vertical depths below surface up to about 400m (1,300ft) depending on the overlying overburden thickness and are flanked above and below by sandstone-shales and limestone beds respectively. The overburden consists of muskeg, sand, gravel and clay (largely unsuitable for farming).
100071 Bitumen is a tar like substance comprising various types of petroleum products ranging from asphaltenes to light petroleum with approximate parameters and composition, according to the API, of specific gravity = 8 -14 , C = 83.2%, H = 10.4%, 0 = 0.94%, N =
0.36% and S
4.8%. Currently the bitumen is initially recovered from the host deposit and then either sold as is or up-graded by distillation plus reduction of S and N and addition of H to become more valuable types of petroleum products. Raw bitumen is worth about 75% of the quoted price of Saudi oil. Accordingly bitumen is initially upgraded into two fractions: one containing about 30% of the bitumen with the heavier hydrocarbons including asphaltenes and the remainder being lighter hydrocarbons similar to Saudi crude. The fractions are refined to more valuable products.
[0008] As used herein, the "oil" in oil sands and other host materials is intended to comprise various petroleum oils particularly heavy oil and bitumen which include asphaltenes. Normally these recovered oils are subject to various fractionations and hydrocracking to derive desired useful products.
[00091 Further background and prior art are described in related United States Application No.
12/381,918 filed March 18, 2009.
[0010] Various processes for recovering oil from oil sands and the like by solvent extraction and in situ pooling and leaching have been studied particularly in the years from about 1970 to 1985.
Hot water, steam and petroleum-based solvents and diluents have been tried without real success.
Apparently no significant commercial operation of this type has existed: it is understood that high solvent losses, low overall recoveries and other operating problems as well as competitive pressures, have kept such operations from being cost effective. Typical references include: US
Patent Nos. 3,858,654; 3,881,550; 3,929,193; 4,474,238; 4,510,997 and GB
Patent No.
2,136,034.
[0011] Kenchington et al. in "Energy Sources", Vol. 5, No. 4, 1981, pp. 317-338 summarizes cost parameters for solvent extraction of mined oil sands using petroleum cuts or blends of C6-C9 aliphatics and aromatics. Brief mention is made on p. 318 of in situ processes for oil sands too deep to mine in which a steam or flame front is generated to drive distilled and cracked product to a recovery well. No direct ISLM technique is mentioned.
[00121 As described in United States Patent Application No. 12/381,918 selected plant-derived non-aqueous liquids are unexpectedly advantageous solvents for oil extraction including in situ leach mining of oil-bearing deposits. In particular monoterpenes having the formula C10H16 have been found very suitable for e.g. in situ leaching of deposits having heavy oils ¨ bitumen ¨
kerogen asphaltenes therein. These monoterpenes are a renewable resource and are by-products of citrus fruit processing and wood harvesting and are biodegradable.
[0013] The use of a biodegradable non-toxic, non-carcinogenic, plant-derived solvents lead to degradation of residual amounts of solvent left following its application and enables environmentally-sustainable resource development. Especially in the case of remediation of contaminated sites, the residual monoterpene solvent after in situ leaching is believed to enhance the overall biodegradation of solvent - plus-oil remaining at the site, and expedite remediation.
This is not feasible with non-renewable petroleum-based solvents.
[0014] Selected monoterpenes include:
Item Boiling Point (range) Flash Point Limonene (d or 1) 176-177 C
Dipentene (d + 1) 175-176 C 45 C
p-Pinene 164-169 C 47 C
a-, P-Terpinene 180-183 C
[0015] Monoterpene leachants preferably are selected to comprise at least one of limonene (d or 1), dipentene, 13-pinene and a- and I3-terpinene.
[0016] Preferred monoterpenes include d-limonene, 1-limonene and dipentene.
[0017] a-pinene has a boiling point of 156-160 C and flash point of 32 C and would require appropriate handling precautions: it would be more suitable for use in winter conditions.
[0018] It has been found that these monoterpenes are able to provide leachates of pumpable viscosities when present in amounts as low as about 20% by volume of the leachate. They are able also to allow and withstand repeated separation and recycling steps.
[0019] Monoterpenes such as limonene and dipentene are much less toxic than mineral spirits (and toluene), are non-caustic, non-reactive to metal surfaces, non-carcinogenic or mutagenic and are readily biodegradable. Due to their flash points these selected monoterpenes should be handled with appropriate care. They are currently regulated as volatile organic compounds (VOC), however their use with recycling should not result in the release into the environment of any more materials than would occur naturally.
[0020] D-limonene is listed as a non-toxic chemical in the Toxic Substances Control Act (TSCA). It is not listed within the Species At Risk Act, Title III compound and is not regulated by the Clean Air Act. The product is also classified as a food additive and has been granted the FDA's GRAS (Generally Recognized As Safe) status. The Environmental Protection Agency (EPA) regulates the use of d-limonene when insecticidal properties are claimed. It coagulates if exposed to sunlight but this can be prevented by the addition of a small amount of an antioxidant e.g. butylated-hydroxy-toluene (BHT) which is also used for human consumption.
Other antioxidants such as phenyl-beta-naphthamine and di-tert-butyl-para-cresol may be used. D-limonene is manufactured inter alia by Florida Chemical Company Inc, 351 Winter Haven Blvd, Winter Haven FL 33881-9432, USA, tel. 863.284.8493. It is available through major distributors e.g. EWR International Inc, 1310 Goshen Parkway, West Chester PA, 19380, USA, tel 619.431.1700. It is understood to be available also from producers in Brazil and Asia inter alia.
[0021] Dipentene is available, similarly and compared to d-limonene, is more resistant to oxidation.
[0022] As outlined in United States Patent Application No. 12/381,918, it has been found that the porosity and permeability of the Athabaska oil sands deposits and their underlying oil bearing carbonate rocks plus the oil bearing sandstones in the USA, as shown in the following table, renders them excellent candidates for ISLM according to this invention. In addition the necessary permeability to enable ISLM may be created in formations such as shale deposits by hydrofracturing them with the addition of particles such as aluminum oxide acting as propants to hold fissures open and thus allow access to the oil deposits, as known to those skilled in the art.
Item porosity permeability Athabasca oil sands About 35 % About 35 D
Athabasca carbonate rocks About 20 % 100-104 mD
USA sandstones About 16%-22% 100mD¨ 600mD
[0023] In order to perform in situ leaching (ISL), the target deposit permeability should preferably be at least about 100mD.
[0024] Bitumens and particularly the asphaltenes therein are the components of the oil in oil sands and the like, which are most difficult to dissolve and maintain in solution. Toluene is known to be a very good solvent for bitumen including asphaltenes. In comparison tests, limonene was found to be a good solvent for bitumen and shale oils (approaching toluene in effectiveness) and able to keep the asphaltenes from precipitating. Naphtha was found unable to prevent the asphaltenes from precipitating forming blocks preventing solution travel during pipeline transportation (in effect acting as asphaltene precipitant).
SUMMARY OF THE INVENTION
[0025] In the course of further testing (flowing from United States Patent Application No.
12/381,918) it was found that in many cases, particularly where longer ISLM
runs and/or reduced porosity occurred, there were significant increases in viscosity and back pressure leading to low efficiencies and poor recoveries. The cause was found to be asphaltene build-up in the leachate. It was discovered that adding selected precipitants for asphaltenes to the leachant led to particulates of asphaltenes being formed in situ with only the very fine ones moving with the leachate and with no significant reduction in leachate flow rate over time.
[0026] The most effective asphaltene precipitants for maintaining leachate flow rates were found to be selected alcohols e.g. within the C2 to Clo range. While certain hydrocarbons function as asphaltene precipitants they have been found to be less effective in this leachate context compared to e.g. isopropanol. While less effective than selected alcohols, they are considered able to maintain sufficient flow rates (leachate) to be operative (see Example 2).
[0027] Preferably the process of the invention incorporates a leachant, e.g. d-limonene, which contains a precipitant, e.g. isopropanol, to selectively dissolve the heavy oil from bitumen, while at the same time precipitating or preventing the asphaltenes from dissolving.
Using ISLM
methods the heavy oil is recovered along with fine particulate asphaltene, clays and silts. The asphaltene, clay and silt particles, and any groundwater present, are removed by centrifuge for deposition or sale. The leachant-precipitant is removed from the heavy oil e.g. by vacuum distillation and recycling back into the well-field forming a closed loop process for further use.
[0028] The process of the invention incorporates a precipitant, e.g. a selected alcohol or hydrocarbon, used in conjunction with the leachant to prevent asphaltene from increasing the viscosity of the leachate in the site or oil-field. This in effect eases flow through within a well-field while conducting ISLM or at a processing site.
[0029] A particular benefit of the process would be to approximately double the monetary value of the oil sands deposits for which it is used. This is because it can recover over 95% of the contained oil compared to about 50% or less by current technology. It also should be able to advantageously recover the oil by-passed by steam-assisted gravity drainage (SAGD) and open-pit mining (OPM) and contained in the sandstone and carbonate rocks that is considered to be uneconomic by existing technology. Test results also disclose the ability of selected monoterpenes e.g. d-limonene to leach oil from a shale deposit.
[0030] In one embodiment the oil sands or similar host materials are in their original deposit location and are subject to in situ leach mining using the selected leachant and the loaded leachate removed and passed to a processing site.
[0031] In some cases the host materials are open-pit mined and transported to a processing site for steps upgrading.
[0032] It is also intended that the host material may be oil and asphaltene-contaminated soil (including sub-soil) that is treated in situ or off-site for the purpose of remediation.
[0033] The process (as defined herein) broadly covers leaching bitumen or oil from oil sands and like host materials containing asphaltenes with a selected leachant which also leaches asphaltenes with the improvement comprising including in the leachant an additive selected to precipitate asphaltenes, the additive being present in an amount sufficient to maintain an operative leachate flow rate through the host materials throughout the leaching process.
[0034] The precipitant additive preferably is a selected alcohol (as described herein) but may be a hydrocarbon selected from pentane, heptane and a selected naphtha. When the additive is a naphtha, it may be retained in the recovered oil as a thinner for pipelining.
The additive may be a combination of a selected alcohol with a selected naphtha, and only the alcohol is recovered for recycling before pipelining.
[0035] The invention includes a leachant composition comprising monoterpene leachant and an additive selected to precipitate asphaltenes; as well as the resulting leachate including leached oil from which asphaltenes have been precipitated. More specifically the invention includes leachate compositions comprising selected alcohol precipitant for asphaltenes, monoterpene leachant and oil leached from oil- and mineral-containing host materials.
[0036] More preferably the invention includes a process of separating oil from oil sands and similar oil- and mineral-containing host materials wherein asphaltenes are present comprising contacting the host materials with a combined leachant-plus-precipitant in which the leachant is a selected monoterpene and the precipitant is an alcohol selected to precipitate asphaltenes sufficiently to enable desired leachate flow rates; removing the oil-loaded leachate from the host materials; separating entrained asphaltene, silt and clay particles from the leachate; separating the leachant and precipitant from the leachate for recycle; and recovering the separated oil and optionally separated asphaltene particles for further treatment.
[0037] The alcohol precipitant preferably is at least one selected from saturated aliphatic and alicyclic mono- and di-hydric alcohols having from 2 to 10 carbon atoms.
[0038] More preferably the alcohol is selected from the group isopropanol, propylene glycol, pentanol, cyclohexanol and decanol.
[0039] Optionally the process may include a subsequent wash of the leached host material with a selected aqueous liquid to recover residual asphaltene particles from the host materials, and the combined recovered asphaltene particles treated to isolate useful components.
[0040] The alcohol precipitant is used in selective effective amounts within the range from about 30 to about 90 % by volume of the monoterpene leachant. A preferred range for isopropanol is about 50 to 70% by volume. Usually the amounts are chosen to result in adequate leachate flow rates in the host material.
BRIEF DESCRIPTION OF DRAWINGS
[0041] Figure 1 depicts the streamline flow leaching pattern of a regular five spot well system with corner guard wells. It illustrates one general technique of the method that would be employed to perform ISLM.
[0042] Figure 2 depicts a wellfield consisting of four adjoining regular five spot well systems. It illustrates the general layout of a wellfield to perform ISLM. The size of the well systems and therefore the resulting wellfield and the resulting oil production, are based on the relevant hydrologic parameters understood by those skilled in the art.
[0043] Figure 3 depicts a conceptual injection/recovery straddle packer system for use in wells.
In one embodiment packers are the heart of each well system enabling solution delivery to and recovery from specific parts of the area to be leached.
[0044] Figure 4 is a conceptual depiction of a process flowsheet to recover oil (and asphaltene) contained in oil sands, carbonate rock (limestone), sandstone or shale oil deposits.
[0045] Figure 5 depicts in cross-section a conceptual ISLM system to recover oil from an oil sands and/or underlying carbonate rock with oil deposit containing asphaltenes.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS
[0046] The process usually employs two steps to selectively recover crude oil and asphaltene directly from bitumen in oil sands deposits. Associated particles of asphaltene, clay and silt can be selectively recovered from the leachate e.g. by use of a centrifuge,and the leachant and precipitant can be removed from the remaining crude oil e.g. by use of vacuum distillation. The remaining oil can be transmitted by pipeline, to a refinery, if desired adding condensate for thinning. The process flowsheet may for example consist of one centrifuge, a vacuum distillation unit and mixer to accomplish selective recovery of asphaltene, and oil (which latter may then be mixed with naphtha (or condensate) for thinning to enable easier pipeline transmission. The leachant-precipitant mixture is recovered for re-use, and asphaltene plus clay and silt particles are discharged; or the asphaltene is separated and recovered for use or treatment.
[0047] ISLM performed on sand, carbonate rock, sandstone or shale oil deposits to recover oil entails injecting leachant through the deposit to dissolve the oil into a leachate that is then treated to separate the oil from the leachant and recycle leachant for further leaching. Figure 1 illustrates the basic principle of ISLM. It depicts the computer generated stream lines of a solution flowing from an injection to recovery points in a permeable medium. The leachant is injected into the deposit via pipes inserted in the deposit according to a wellfield design based on hydrologic modeling studies and ISLM tests conducted on the deposit. The leachate is treated to recover the oil for sale, remove the leachant for re-use and discard associated water if necessary.
[0048] The well system shown in Figure 1 consists of five vertical wells installed in a square pattern in a geologic formation of suitable porosity and pernieability. One of the wells is located in the center of the pattern to inject solution (leachant) to dissolve or target oils thereby forming a leachate. A vertical well is also located at each corner of the pattern to conduct pumping forming sinks to recover the leachate. The leachate is discharged to the plant for treatment.
[0049] Guard wells (if required) surround the well system according to modeling studies. Their purpose is to recover groundwater to reduce its ability to dilute recovered leachate. The water they collect is discharged at a suitable distant site.
[0050] The stream flow lines depict the paths of individual segments of the leachant moving toward a recovery well. The segments outside of the well system boundary will leach the relevant area traversed and attract ground water if present. Potential leachate excursion in the course of ISLM recovery (i.e. wandering beyond the well system) is regarded as unimportant because of its organic similarity to and therefore compatibility with its environment particularly due to the biodegradable leachant selected.
[0051] An inverted well system involves injection performed by the four peripheral wells and recovery by the central well. Its choice as well as that of either a regular or inverted polygonal well system (providing more recovery wells to offer dilution abatement and leaching advantages) is indicated by modeling.
[0052] The first steps of the ISLM process are to define the geologic and hydrologic parameters of the oil deposit to perform modeling studies. Parameters include (a) extent/variation in bitumen concentration and contained oil and (b) porosity, pemteability, solution travel time between injection and recovery wells, groundwater amount and flow direction and size/distribution of fractures that could affect leaching. This information enables the design of a wellfield to yield the desired rate of oil recovery.
[0053] It may be necessary to increase the permeability of a deposit to enable satisfactory ISLM
or to strengthen the walls of the installed wells to prevent caving or to plug channels in the deposit or surrounding formation that act as short circuits preventing proper leachant delivery.
These tasks can be performed by people skilled in the art. The first can be achieved by hydro-fracturing the deposit (i.e. injecting high pressure water with the addition of aluminum oxide particles to force and prop open fractures necessary for the purpose).
Strengthening well hole walls is accomplished by electrical induration. Preventing potential short circuit channels entails mapping their routes by water injection temperature sensing and then plugging them at selected locations by injecting cement grout.
[0054] Injection and recovery wells are purpose drilled vertical holes about 15cm (6 in) outside diameter (OD) according to the selected wellfield pattern. They extend from ground surface to the bottom of the portion of the deposit selected for ISLM. They are cased from surface into the top of the deposit to strengthen the well mouth.
[0055] For example, in Figure 2, leachant is supplied to the wellfield from the treatment plant via a single pipe e.g. consisting of high density PVC, lying on ground surface and usually extending to a pump house. From there leachant is distributed by individual pipes (e.g. PVC) to the respective injection well heads where a high pressure pump injects it into the host material.
Sensors installed in the individual pipes record relevant parameters including speed, volume and chemistry. This information is relayed to the control centre in the plant to guide changes in the leachant delivery protocol and to forecast estimated oil production.
Continuous solution movement in pipelines prevents freezing. In the event of plant delays e.g. in winter, solutions can be recycled through the deposit until operations resume. Recovery well pumps usually send their leachate to the pump house where it is combined into a single pipe to the plant.
[0056] The main concern of ISLM is to insure efficient delivery of leachant through the deposit to provide sweep efficiency and to prevent loss of leachate. In the circumstances the latter is not a serious issue because of the extensive expanse of oil host surrounding the area being mined identical in nature to the leachate components plus the absence of toxic chemicals being used.
[0057] In one aspect each well is fitted with a straddle packer system e.g. as depicted and described in Figure 3 consisting of a pipe e.g. stainless steel, extending from surface to the bottom of the wellbore. It is perforated along its portion traversing the target extraction section to enable injection or recovery of leach solutions. The pipe is sized for the injection pressure and amount of solution to be delivered. It has rubber packer sleeves above and below the perforated sections that can be hydraulically expanded to form a 20,000 psi seal with the well bore to prevent upward migration of solutions. Packer systems intended to recover rather than inject solutions are fitted with internal submersible pumps rather than external injection pumps.
[0058] Well holes are drilled to a depth slightly beyond that of the oil matrix section to undergo leaching and to accommodate the packer system e.g. as in Figure 3. A metal casing is inserted into the top of the well hole to a depth slightly deeper than the overburden to stabilize the well entrance. A straddle packer system is installed in the well hole to sequester the section to be leached and to deliver leachant and recover leachate.
[0059] The packer preferably consists of a sectional pipe e.g. 316 stainless steel, extending from the top to bottom of the wellbore. The central service portion covers the section of the well intended for leaching. Its OD is slightly less than the inside diameter (ID) of the wellbore and is perforated to enable injection or recovery of solutions. It may be fitted with two adjustable double rubber sleeves (packers) one at each end of the section. The sleeves can be compressed longitudinally by hydraulic rams to expand laterally forming a 20,000 psi seal with the wellbore to prevent vertical migration of fluids thereby sequestering (i.e. packing off) the section to be leached.
[0060] A shorter narrower delivery pipe is attached to the upper end of the service pipe to convey leachant to or leachate from the packer service pipe section. It also houses the hydraulic fluid line to the rams and the electrical supply cord to the submersible pump.
[0061] The packer is fitted with a submersible electric pump if it is intended to recover leachate rather than inject leachant. The pump exit is attached to the bottom of the service pipe to discharge leachate through it to surface where it is conveyed to the plant.
[0062] As examples for ISLM there are two standard ISLM well system arrays described herein with differing attributes designed to inject and recover solutions. A regular five spot well system consists of a square pattern with a vertical well at the centre of the square to inject leachant to dissolve intervening material plus a vertical well at each corner of the pattern to recover resulting leachate. An inverted five spot well system injects leachant at the corner wells and recovers leachate from the central well. A series of adjoining well systems constitutes a wellfield. The addition of guard wells with recovery pumps appropriately placed around a well system or wellfield perimeter discharging such water at a suitable distant site can greatly assist in reducing groundwater dilution of recovered leachate. The optimum design of a well system as to shape (square or polygonal), regular or inverted and guardwell locations, to maximize sweep efficiency is based on ISLM field tests and modeling studies.
[0063] In practice, a wellfield necessary to recover the target amount of oil is installed in the oil-bearing deposit according to a pattern based on modeling studies and hydrologic tests. Leach solution (leachant) is injected through the deposit via some of the wells to selectively dissolve the calculated amount of oil. Resulting pregnant solution (oil/monoterpene leachate) is extracted through adjacent wells and pumped to the treatment plant where the leachant, the dissolved oil and any associated water are recovered selectively.
[0064] An ISLM well-field to recover oil from a deposit is conceptually depicted in Figure 2. It comprises four adjoining regular five spot well systems with central wells injecting leachant plus peripheral pumping wells that recover the leachate. A treatment system selectively recovers the resulting monoterpene-oil leachate by rejecting its associated groundwater.
[0065] Because of the differing oil deposits (i.e. in sand or carbonate rocks), the straddle packer that would be employed (e.g. in Figure 3) must be adjusted to suit the material being leached. If the deposits have different permeabilities they cannot be leached together because the one with higher permeability will short circuit the other. Consequently the lower permeability zone must be increased by hydrofracturing to equal the adjoining permeability or both deposits leached separately.
[0066] Referring to the blow up in Figure 5 showing the sand grains microscopic examination has revealed that such grains (plus their associated bitumen patches) are surrounded by a thin layer of water that evidently enables leachant plus precipitant to migrate along the hydrophilic surfaces of sand and to reach bitumen which facilitates the leachate phase-particle separation in situ and also in subsequent processing. (Microscopic Structure Of Athabaska Oil Sands, Koichi Takemura, Canadian Journal of Chemical Engineering, vol. 60, August 1982).
[0067] The process has the potential of recovering oil resources from low grade or small deposits in contrast to other processes that would not be economical for same. It is versatile and capable of high recovery and output well beyond that by conventional technologies currently in use to recover oil and/or bitumen from the foregoing deposit types. Moreover it does so in a more advantageous manner. It can achieve oil recovery at comparatively lower costs with reduced environmental impact because it does not employ steam, can avoid mining operations that create substantial ground disturbance or waste piles and avoids creating contaminated or toxic discharges.
[0068] One example of ISLM entails installing a series of vertical pipes according to a selected certain pattern (wellfield), into a geological formation of suitable porosity and permeability to permit a leachant- precipitant to be pumped through the formation via some of the (injection) pipes to dissolve target constituents. The resulting leachate is recovered to surface for treatment via the remaining (recovery) pipes.
[0069] This technique employing selected monoterpenes would aim to recover oil/bitumen almost completely from host deposits at comparatively low cost and virtually no environmental impact. Groundwater dilution of the oil/bitumen can be prevented by appropriate wellfield design employing guard wells and/or electric fences. Extracted groundwater may be treated to meet statutory regulations and re-injected into the earth at a selected site or otherwise suitably disposed of [0070] The permeability of a deposit can be increased if necessary to perform ISLM by means well known to those skilled in the art. A standard method is to adopt the procedure employed by water well drillers to hydrofracture the deposit by injecting high pressure water at up to 20,000 psi or more to separate portions of the deposit and adding a propant such as fine particles of aluminum oxide to keep the separated portions apart. The limonene or other monoterpene leachant can be recovered from the oil/bitumen leachate e.g. by vacuum distillation. It is recycled for further leaching and the oil/bitumen/asphaltene components recovered for sale or refining to more valuable products.
Estimated oil recovery from hypothetical block of oil sands [0071] The average thickness of various oil sands layers in Alberta is reported to be about 20m (i.e. about 66ft). Assuming the permeability of such oil sand of about 35 Darcies a wellfield area 600ft square over half that depth of oil sand would represent an oil sands block amounting to 600x600x33 ft = 12x106 ft3 and that is easily within the capability of ISLM in one day given the permeability of the target material.
[0072] Assuming average bitumen content = 8% therefore the contained bitumen in the zone =
10x105 ft3. At 5.62 ft3 bitumen/US bbl therefore this represents 1.78 x105 US
bbl/d of bitumen.
Assuming 70% bitumen = oil (balance is asphaltene) the foregoing = 1.246x105 US bbl/d of oil =
455 x 105 US bbl/yr of oil and @ $50/b = $2 x 109/yr.
[0073] The foregoing ISLM estimation demonstrates the potential value of oil recovery from oil sands/carbonate oil bearing rock or oil shales that can be achieved.
[0074] Oil from the foregoing sources is regarded as heavy oil. Apart from oil sands its normal rate of production by North American producers is less than about 100,000 US
bbl/d. Two of the current fourteen Athabaska oil sands operators produce about 200,000 US bbl/d and are scheduled to increase output to about 350,000 US bbl/d. As these calculations indicate, an ISLM
project involving a well-field 183 m2 (600ft2) x 10m (33ft) deep could produce about 125,000 US bbl/d of oil based on conservative figures. Expanding this output could be possible, by appropriate extended use of the present invention.
[0075] In many cases the recovered asphaltenes contain valuable components, in particular trace metals and rare earths (oxides) whose value justifies recovery treatment. For example it is known that Alberta oil sand asphaltenes contain vanadium oxide usually in amounts to justify recovery.
EXAMPLES
[0076] The following examples are meant to illustrate but not limit the invention.
[0077] Laboratory tests have indicated that the addition of monoterpene leachant in excess of the volume of the pore space will readily leach bitumen from oil sands in an open vessel. Scalable tests (laboratory tests that can be scaled up to full field conditions) indicate that plugging occurs when flow through of leachant is attempted under lower porosity confined conditions. It was suspected that the rate of change in viscosity by the asphaltenes caused the observed blockage and pressure increase. Use of push-pull ISLM methods alleviated the problem but increased the time required to leach an oil sand well-field. However, when the asphaltene was absent from the leachate (by precipitation), the viscosity problem was solved and the fine asphaltene could be removed easily with the silt and clays by flow-through ISLM methods. This was achieved by introducing a selected asphaltene precipitant, e.g. isopropanol, to the d-limonene leachant as described herein.
[0078] In order to prove this method, gravity leaching tests (gradient = 1) were performed on similar samples of oil sand, packed to represent reservoir conditions, in vertical glass tubing. The leachant in the first test was 100% d-limonene, while in the second test a selected precipitant was added to the leachant to form a 50:50 mix by volume of d-limonene and isopropanol. In the first test, leachate recovery slowed to a trickle by the second pore volume of leachant; due to pore plugging caused by viscosity and pressure increases. In the second test the leachate mixture was recoverable at a constant free flow rate. The leachate from this second test consisted of a mixture of crude oil, d-limonene, isopropanol as a single phase, and particles of asphaltene, clay and silt.
D-limonene dissolution of bitumen [0079] Laboratory tests disclosed that the ratio of d-limonene to bitumen for the leachate to provide highest flow rate was about 54gm bitumen/liter of d-limonene. One liter of limonene is able to render pumpable up to about 40g oil from oil sands. Isopropanol precipitation of asphaltene. Laboratory testing indicated that isopropanol when introduced to a d-limonene leachate loaded with dissolved bitumen will, when used in the same volumes as naphtha, pentane and heptane, precipitate more asphaltene from the leachate than the latter hydrocarbons.
Selective leaching of bitumen using a d-limonene/isopropanol leach [0080] A leachant consisting of 50% d-limonene and 50% isopropanol was found to leach bitumen while at the same time causing the precipitation (separation) of the asphaltenes. This facilitates flow within the well-field so that ISLM flow-through methods can be feasible. These methods are much faster and more efficient than are the push-pull methods that must be considered when using a 100% d-limonene leach.
[0081] Isolation of the asphaltenes using the above method expedites pre-pipeline upgrading by enabling removal of entrained asphaltenes, silts and clay particles e.g. by use of a dynamic centrifuge as opposed to more time consuming chemical methods. The isolation and recycling of the d-limonene and the isopropanol can be achieved by use of vacuum distillation; leaving the de-asphaltened crude oil ready for shipment to refinery by pipeline. In the case where the oil is too thick, selected condensate (naphtha) can be added as a thinner (see Fig.
4).
[0082] One preferred ISLM process is to carry out in situ leaching utilizing a mixed leachant consisting of d-limonene as a solvent and isopropanol as a precipitant and employing a well-field consisting of adjoining regular or inverted five spot well systems with guard wells linked together to recover oil/ and asphaltene from either an oil sands, carbonate rock or a sandstone deposit as in Fig. 1 plus Fig. 4. Recovered ground water can be recycled in situ to wash out residual asphaltene particles.
Claims (14)
1. A process of separating oil from oil sands and similar oil- and mineral-containing host materials wherein asphaltenes are present, comprising:
a) contacting the host materials with a combined leachant plus precipitant in which the leachant is a selected monoterpene and the precipitant is an alcohol selected to precipitate asphaltenes sufficiently to enable desired leachate flow rates;
b) removing the oil-loaded leachate from the host materials;
c) separating entrained asphaltene, silt and clay particles from the leachate;
d) separating the leachant and precipitant from the leachate for recycle;
and e) recovering the separated oil and optionally separated asphaltene particles for further treatment.
a) contacting the host materials with a combined leachant plus precipitant in which the leachant is a selected monoterpene and the precipitant is an alcohol selected to precipitate asphaltenes sufficiently to enable desired leachate flow rates;
b) removing the oil-loaded leachate from the host materials;
c) separating entrained asphaltene, silt and clay particles from the leachate;
d) separating the leachant and precipitant from the leachate for recycle;
and e) recovering the separated oil and optionally separated asphaltene particles for further treatment.
2. The process of claim 1, wherein the alcohol precipitant is at least one selected from saturated aliphatic and alicyclic mono- and di-hydric alcohols having from 2 to 10 carbon atoms.
3. The process of claim 2, wherein the precipitant is selected from the group consisting of isopropanol, propylene glycol, pentanol, cyclohexanol and decanol.
4. The process of claim 1, wherein a subsequent wash with selected aqueous liquid is carried out to recover residual asphaltene particles from the host materials, and the combined recovered asphaltene particles treated to isolate useful components.
5. The process of claim 1, wherein the alcohol precipitant is present in selected effective amounts from about 30 to about 90% by volume of the monoterpene leachant.
6. The process of claim 3, wherein the precipitant is isopropanol in amounts of about 50 to about 70% by volume based on the monoterpene leachant.
7. A leachant composition for oil sands and like mixtures containing asphaltenes comprising monoterpene leachant and an additive selected to precipitate asphaltenes.
8. A leachate composition comprising the leachant of claim 7 and oil from which asphaltenes have been precipitated.
9. In a process for leaching bitumen or oil from oil sands and like host materials containing asphaltenes with a selected leachant which also leaches asphaltenes, the improvement comprising including in the leachant an additive selected to precipitate asphaltenes, the additive being present in an amount sufficient to maintain an operative leachate flow rate through the host materials throughout the leaching process.
10. The process of claim 9 wherein the leachant is a selected monoterpene.
11. The process of claim 9 wherein the additive is a selected alcohol.
12. The process of claim 9 wherein the additive is selected from pentane, heptane and a selected naphtha.
13. The process of claim 12 wherein the additive comprises a selected naphtha which is retained in the recovered oil as a thinner for pipelining.
14. The process of claim 9 wherein the additive is a combination of a selected alcohol with a selected naphtha and only the alcohol is recovered for recycling before pipelining.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2779238A CA2779238A1 (en) | 2012-06-08 | 2012-06-08 | Selective leach recovery of oil (and asphaltene) from oil sands and like materials |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2779238A CA2779238A1 (en) | 2012-06-08 | 2012-06-08 | Selective leach recovery of oil (and asphaltene) from oil sands and like materials |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2779238A1 true CA2779238A1 (en) | 2013-12-08 |
Family
ID=49753562
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2779238A Abandoned CA2779238A1 (en) | 2012-06-08 | 2012-06-08 | Selective leach recovery of oil (and asphaltene) from oil sands and like materials |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2779238A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015065798A1 (en) * | 2013-10-30 | 2015-05-07 | Chevron U.S.A. Inc. | Process for in situ upgrading of a heavy hydrocarbon using asphaltene precipitant additives |
| US10975291B2 (en) | 2018-02-07 | 2021-04-13 | Chevron U.S.A. Inc. | Method of selection of asphaltene precipitant additives and process for subsurface upgrading therewith |
| CN114477714A (en) * | 2021-12-27 | 2022-05-13 | 上海丛麟环保科技股份有限公司 | Recovery treatment method for tank cleaning oil sludge |
-
2012
- 2012-06-08 CA CA2779238A patent/CA2779238A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015065798A1 (en) * | 2013-10-30 | 2015-05-07 | Chevron U.S.A. Inc. | Process for in situ upgrading of a heavy hydrocarbon using asphaltene precipitant additives |
| US9670760B2 (en) | 2013-10-30 | 2017-06-06 | Chevron U.S.A. Inc. | Process for in situ upgrading of a heavy hydrocarbon using asphaltene precipitant additives |
| US10975291B2 (en) | 2018-02-07 | 2021-04-13 | Chevron U.S.A. Inc. | Method of selection of asphaltene precipitant additives and process for subsurface upgrading therewith |
| CN114477714A (en) * | 2021-12-27 | 2022-05-13 | 上海丛麟环保科技股份有限公司 | Recovery treatment method for tank cleaning oil sludge |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9410405B2 (en) | Compositions and methods for enhanced hydrocarbon recovery | |
| US8534359B2 (en) | Leach recovery of oil from oil sands and like host materials | |
| US20130045902A1 (en) | Composition and method for recovering heavy oil | |
| AU2014302576B2 (en) | Remediation of asphaltene-induced plugging of wellbores and production lines | |
| EP2715060A2 (en) | Compositions, methods, apparatus, and systems for incorporating bio-derived materials in drilling and hydraulic fracturing | |
| US9556717B2 (en) | Non-aqueous hydrocarbon recovery | |
| Almubarak et al. | Recent advances in waterless fracturing fluids: A review | |
| Ali et al. | A critical review of emerging challenges for the oil field waters in the United States | |
| CA2779238A1 (en) | Selective leach recovery of oil (and asphaltene) from oil sands and like materials | |
| Veil et al. | Water issues associated with heavy oil production. | |
| WO2014197110A1 (en) | Camphor and alpha-olefin for inhibiting or dissolving asphaltene or paraffin deposits | |
| Wojtanowicz | Oilfield waste disposal control | |
| WO2013154468A2 (en) | Method for increasing the extraction of oil, gas condensates and gases from deposits and for ensuring the continuous operation of production and injection wells | |
| EP3039097B1 (en) | Haloalkane composition for inhibiting or dissolving asphaltene or paraffin deposits | |
| Fu et al. | Formation damage problems associated with CO2 flooding | |
| King et al. | Environmental aspects of hydraulic fracturing: what are the facts? | |
| Hsu et al. | Production for recovery | |
| CA2820932C (en) | Method for recovering hydrocarbons from a subterranean reservoir | |
| Zoveidavianpoor et al. | Overview of environmental management by drill cutting re-injection through hydraulic fracturing in upstream oil and gas industry | |
| Oskui et al. | Multi-criteria evaluation technique for SFI site identification of NORMS and oil industry waste disposal–Possibilities in Kuwait | |
| Ferreira | Smart Water EOR potential in Brazilian oilfields | |
| Pedchenko et al. | Expanding of spheres the application of borehole hydro-production technology to develop deposits of non-traditional hydrocarbons | |
| US3847220A (en) | Miscible displacement of petroleum using sequential addition of carbon disulfide and a hydrocarbon solvent | |
| Zhironkin et al. | Analysis of the Negative Impact of Hydraulic Fracturing Technology on the Environment | |
| Sutherland | Separation processes in oil and gas extraction |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |
Effective date: 20140610 |
|
| FZDE | Discontinued |
Effective date: 20140610 |