WO2011101739A2 - Process for the fluidification of a high-viscosity oil directly inside the reservoir - Google Patents
Process for the fluidification of a high-viscosity oil directly inside the reservoir Download PDFInfo
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- WO2011101739A2 WO2011101739A2 PCT/IB2011/000427 IB2011000427W WO2011101739A2 WO 2011101739 A2 WO2011101739 A2 WO 2011101739A2 IB 2011000427 W IB2011000427 W IB 2011000427W WO 2011101739 A2 WO2011101739 A2 WO 2011101739A2
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- Prior art keywords
- reservoir
- process according
- well
- oil
- microwaves
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 33
- 239000012530 fluid Substances 0.000 claims abstract description 22
- 229910010293 ceramic material Inorganic materials 0.000 claims abstract description 13
- 239000002245 particle Substances 0.000 claims abstract description 5
- 239000003921 oil Substances 0.000 claims description 40
- 239000000463 material Substances 0.000 claims description 19
- 239000004033 plastic Substances 0.000 claims description 16
- 229920003023 plastic Polymers 0.000 claims description 16
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 12
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 10
- 229910000831 Steel Inorganic materials 0.000 claims description 9
- 239000010959 steel Substances 0.000 claims description 9
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- 239000000725 suspension Substances 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 238000005553 drilling Methods 0.000 claims description 3
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 150000001298 alcohols Chemical class 0.000 claims description 2
- 239000000919 ceramic Substances 0.000 claims description 2
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- 229910003465 moissanite Inorganic materials 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 description 16
- 230000015572 biosynthetic process Effects 0.000 description 9
- 238000005755 formation reaction Methods 0.000 description 9
- 239000010779 crude oil Substances 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 238000000605 extraction Methods 0.000 description 4
- 238000011065 in-situ storage Methods 0.000 description 4
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- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 239000004576 sand Substances 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 2
- 238000010796 Steam-assisted gravity drainage Methods 0.000 description 2
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- 230000000638 stimulation Effects 0.000 description 2
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- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
- E21B43/2401—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection by means of electricity
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
- E21B43/2405—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection in association with fracturing or crevice forming processes
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/267—Methods for stimulating production by forming crevices or fractures reinforcing fractures by propping
Definitions
- the present invention relates to a process for the fluidification of a high-viscosity oil directly inside the reservoir.
- the present invention relates to a process for the fluidification of a high-viscosity oil directly inside the reservoir with the use of microwaves/radiofrequencies (RF) .
- RF microwaves/radiofrequencies
- the present invention relates to a process for the fluidification of a high- viscosity oil directly inside the reservoir, with the use of microwaves/ RF, suitable for both on-shore and off-shore production fields.
- oil wells which produce high-viscosity oil for example oil with a viscosity higher than 100 cps, generally ranging from 300 to 10 6 cps, have the necessity of fluidifying the oil directly in situ to favour its flow towards the well and allow the extraction pumps to pump the oil to the surface with a flow-rate which makes the exploitation of the reservoir convenient.
- Reservoirs with these characteristics are, for example, heavy oil reservoirs or tar fields.
- microwaves An alternative to the known thermal stimulation systems is represented by the use of microwaves whose use is described, for example, in the patent USA 3,104,711.
- the use of microwaves generated in situ in the reservoir causes a targeted heating of the crude oil, which facilitates its movement and consequently its extraction.
- microwaves for thermally stimulating crude oil directly in the reservoir is therefore a known process but the actual application in a production well has proved to be not particularly effective due to the limited capacity of the heating effect .
- An object of the present invention therefore relates to a process for the fluidification of a high- viscosity oil directly inside a reservoir which comprises :
- the oil production well can be a vertical or tilted, simple or with one or more branchings which radiate into the reservoir.
- the walls of the well, proceeding towards the reservoir are reinforced with a cylindrical steel structure, called casing, which adheres and is constrained to the walls with cement/mortar or concrete, generally consisting of a mixture of Portland cement and inert aggregates such as siliceous sand and possibly gravel.
- cement/mortar or concrete generally consisting of a mixture of Portland cement and inert aggregates such as siliceous sand and possibly gravel.
- production tubing When the well enters into production, the oil is recovered by means of a specific tubing, known as production tubing. This is a steel tubing which is inserted into the well and also into each branching, until it reaches the level of the reservoir. At the well bottom (also in correspondence with each branching) , the tubing is fixed by means of a combined hydraulic and mechanical sealing system, called packer, which forces the oil to rise to the surface from inside the tubing without touching the walls of the casing.
- packer a combined hydraulic and mechanical sealing system
- the terminal part of the casing downstream of the packer, is made with a cylindrical structure of plastic material, as the organic polymeric materials used as plastic material are much more transparent to microwaves/RF than steel.
- the dimension of the casing section or segment made of plastic material is substantially determined by the dimension of the reservoir and size of the well.
- the segment (substantially circular section) generally has a length ranging from 2 to 20 metres and a wall thickness ranging from 1 to 5 cm.
- the plastic material can be a thermoplastic polymer or a thermosetting resin.
- a polymer such as polypropylene, polyvinylchloride , polyesters (for example PET, PBT) , thermotropic polyesters, "engineering polymers", polyamides etc., can be used, and in the latter case thermosetting polyester resins or epoxy resins can be used.
- the materials can be reinforced with mineral fillers, such as talc or calcium carbonate, and/or with fibrous material such as glass fibres, carbon fibres, aramidic fibres, continuous or short.
- the terminal section of the casing made of plastic material is fixed to the walls of the well with mortar wherein the inert part essentially consists of alumina (A1 2 0 3 ) , which is more transparent to microwaves/RF than silica-based sand.
- the part of casing overlying the section made of plastic material is made of steel.
- the steel part of casing directly above the plastic casing and below the packer in turn comprises the production section, which can be associated with a screen for allowing the oil to flow from the reservoir into the well without producing possible sandy materials, and then rise to the surface through the tubing.
- the second step (b) of the process, object of the present invention envisages injecting into the reservoir, substantially at the bottom of the well, finely subdivided particles of ceramic material having a high thermal conductivity, dispersed in a fluid with a variable viscosity, by means of an induced fracturing operation.
- the induced fracturing operation is, as a general principle, an operation which is applied in the oil industry, for allowing the oil to flow more easily towards the well.
- the induced fracturing operation allows the heat generated by the emission of microwaves/RF to be transferred in depth into the reservoir, by means of fractures which propagate in all directions, and involving, in the heating and fluidification phase, greater volumes of high-viscosity oil with respect to those treated with the methods of the known art .
- Induced fracturing is a known technique which envisages subjecting a fluid having a variable viscosity to high pressure at the well bottom so that this can penetrate into the reservoir by means of a fracture in the geological formation in which the reservoir itself is situated.
- the fluid which under shear stress has a viscous rheological behaviour, entrains a finely subdivided solid material known as "proppant" which is a preservation agent of fractures.
- the suspension viscous fluid + proppant
- the suspension present in the fractures passes from the shaken state, associated with the shear action of the fracture-creating system, to a rest state during which the viscous fluid tends to have a Newtonian fluid rheological behaviour.
- the fluid is slowly absorbed by the reservoir and flow from the fractures diluting in the formation.
- the proppant on the other hand, remains in the fractures consolidating them.
- the fluid with a variable viscosity generally consists of a base selected from water, oil, alcohols, etc., in which a substance is dispersed/dissolved, capable of providing the desired rheological fluid behaviour suitable for producing an induced fracture at the well bottom.
- a substance is dispersed/dissolved, capable of providing the desired rheological fluid behaviour suitable for producing an induced fracture at the well bottom.
- these substances are guar rubber or materials of the type CMHPG (Carboxy Methyl Hydroxy Propyl Guar) or CMHEC (Carboxy Methyl Hydroxy Ethyl Cellulose) .
- the finely subdivided ceramic solid which is dispersed in the fluid having a variable viscosity, as a traditional proppant, preferably consists of silicon carbide, SiC, with a particle-size ranging from 1 to 20 ⁇ , preferably from 1 to 10 ⁇ . This material is preferred as it allows an optimum diffusion of the heat generated by the microwaves/RF .
- the concentration of finely subdivided ceramic material, for example SiC, in the suspension varies from 20 to 60% by weight (calculated with respect to the total of fluid + ceramic material), preferably from 30 to 50%.
- conventional suspending agents surfactants
- silicon carbide is substantially determined by the fact that it is a material with extremely good mechanical properties, among which a high hardness and a high elastic modulus, it has a low density, a low thermal expansion coefficient, an excellent thermal shock resistance and is substantially inert to the chemical products generally present in the reservoir, for example H 2 S, mercaptans, nitrogenated compounds, C0 2 , etc.
- the preferred characteristics of silicon carbide are its good absorbing capacity of microwaves/RF and a high thermal conductivity, which enables the heat generated by the microwaves/RF to be transferred in depth in the reservoir.
- the ceramic material i.e. the silicon carbide
- the ceramic material + steel microbeads is mixed with stainless steel microbeads, in a quantity ranging from 2 to 10% by weight (calculated with respect to the total of ceramic material + steel microbeads) .
- the latter are not transparent to microwaves, they reflect them in all directions improving the diffusion of heat in the fractures and from these towards the reservoir, thus favouring the fluidification of the oil contained therein.
- fractures can be obtained, which are distributed in depth in the geological formation in which the reservoir is present.
- the fractures can be distributed and developed at 360°, in all directions, with lengths which can be greater than 20 metres, generally ranging from 20 to 50 meters, preferably from 25 to 30 metres.
- the part of the well involved in the induced fracturing operation is preferably the terminal part of the casing, which is made of plastic material.
- the casing made of plastic is previously perforated so that the viscous suspension can flow through the corresponding holes.
- the plastic casing is internally covered with a continuous elastic lamina, again made of thermoplastic material, which blocks the holes as it elastically pushes against the internal cylindrical walls.
- the well can enter into production.
- the viscous oil is heated with the microwaves/RF .
- a microwave/RF antenna is lowered to the well bottom, in the bed of the casing made of plastic material, which is capable of irradiating radiofrequencies ranging from 0.1 to 1 GHz or microwaves with frequencies ranging from 1 GHz to 300 GHz and an overall wavelength ranging from 0.001 to 3 metres.
- the antenna is connected, by- cable or waveguide, to a magnetron having a power ranging from 1 to 5 MW, situated on the surface or inside the well in a specific position.
- the antenna continuously emits microwave beams/RF which are diffused in the formation and reservoir at 360° in all directions.
- the microwaves encounter both the reservoir and the fractures filled with ceramic material, in particular silicon carbide (SiC) and possibly stainless steel microbeads.
- SiC silicon carbide
- the electromagnetic waves are absorbed by the SiC and homogeneously reflected by the stainless steel beads in all directions and transformed into heat which is further diffused in the reservoir.
- the fractures become further heat sources which penetrate the reservoir allowing greater volumes of viscous oil to be fluidified with respect to those fluidified with the methods of the known art .
- the numerical reference (1) indicates the reservoir in which a heavy crude oil is contained.
- the reference number (2) indicates the steel casing whose terminal part, reference number (3) indicates the screen or "production section or area" .
- the reference number (5) indicates the fractures filled with the thermally conductive ceramic material, for example with Sic, whereas the reference numbers (6) and (7) respectively indicate the antenna for microwaves/RF and the cable or waveguide which connect the antenna to the magnetron, not illustrated in the Figure .
- the dashed and compact arrows respectively indicate the microwaves/RF emitted by the antenna, reference number (8) , and the flow of heated and fluidified oil, reference number (9) , which moves from the reservoir towards the production area.
- the antenna (6) transmits beams of microwaves or radiofrequencies (8) which are diffused in the reservoir (1) and cause its heating.
- the waves also encounter and heat the SiC contained in the fractures (5) .
- the SiC can be easily heated and allows the heat to be transferred in depth inside the reservoir.
- the hot oil which is consequently more fluid (9) can be easily transferred towards the production area (3) to rise into the casing (2) towards the pumping system (not illustrated in the Figure) which will take it to the surface by means of the tubing.
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
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- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
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Abstract
Process for the fluidification of a high-viscosity oil directly inside a reservoir which comprises injecting into the reservoir, substantially at the bottom of the well, finely subdivided particles of ceramic material having a high thermal conductivity, dispersed in a fluid with a variable viscosity, by means of an induced fracturing operation and installing, substantially in correspondence with the fractured area, a microwave/RF emission antenna connected by means of a waveguide or cable, to a magnetron.
Description
PROCESS FOR THE FLUIDIFICATION OF A HIGH-VISCOSITY OIL DIRECTLY INSIDE THE RESERVOIR
The present invention relates to a process for the fluidification of a high-viscosity oil directly inside the reservoir.
More specifically, the present invention relates to a process for the fluidification of a high-viscosity oil directly inside the reservoir with the use of microwaves/radiofrequencies (RF) .
Even more specifically, the present invention relates to a process for the fluidification of a high- viscosity oil directly inside the reservoir, with the use of microwaves/ RF, suitable for both on-shore and off-shore production fields.
As is known, oil wells which produce high-viscosity oil, for example oil with a viscosity higher than 100 cps, generally ranging from 300 to 106 cps, have the necessity of fluidifying the oil directly in situ to favour its flow towards the well and allow the extraction pumps to pump the oil to the surface with a flow-rate which makes the exploitation of the reservoir convenient. Reservoirs with these characteristics are, for example, heavy oil reservoirs or tar fields.
The fluidification of heavy/viscous crude oils or non-conventional oils, such as tars, oil sands, oil shales, etc., directly in the reservoir is, however, an extremely difficult operation.
For the extraction of viscous oils, it is known to
use advanced techniques, such as CSS (Cyclic Steam Simulation) or SAGD (Steam-Assisted Gravity Drainage) , which are based on injections of hot steam into the reservoir to fluidify the oil and favour its movement towards the well and therefore its emission onto the surface. Techniques of this type are also defined as "thermal stimulation" of the reservoir. Other known alternative techniques envisage the injection of hot C02 or combustion in situ.
For effecting the above techniques, however, either large water and energy consumptions are required, for the production and injection of vapour and/or C02, or a combustion must be effected at the well bottom which implies considerable risks. Furthermore, the implementation of these techniques can be problematical in off-shore environments where the availability of space is not excessive.
An alternative to the known thermal stimulation systems is represented by the use of microwaves whose use is described, for example, in the patent USA 3,104,711. The use of microwaves generated in situ in the reservoir causes a targeted heating of the crude oil, which facilitates its movement and consequently its extraction.
Applications of this type are also described in patent USA 5,082,054 which indicates how to apply electromagnetic radiations having a suitable frequency to favour the extraction of high-viscosity oils from
reservoirs essentially by means of selective heating induced by microwaves .
Other references in literature which describe the use of microwaves for heating high-viscosity oils in situ are patent application USA 2007/131591 and patent USA 4,419, 214.
The use of microwaves for thermally stimulating crude oil directly in the reservoir is therefore a known process but the actual application in a production well has proved to be not particularly effective due to the limited capacity of the heating effect .
The Applicant has now found, as better illustrated in the enclosed claims, a new way for heating a viscous oil directly in the reservoir with the use of microwaves or radiofrequencies (RF) . This method allows the heat produced by the microwaves or radiofrequencies to be diffused in depth in the reservoir providing a heating effect of the crude oil and consequently its fluidification, higher than that of the known methods.
An object of the present invention therefore relates to a process for the fluidification of a high- viscosity oil directly inside a reservoir which comprises :
a. producing a well by the drilling of an oil field until the oil reservoir is reached;
b. injecting into the reservoir, substantially at the bottom of the well, finely subdivided particles of
ceramic material having a high thermal conductivity, dispersed in a fluid with a variable viscosity, by means of an induced fracturing operation;
c. installing, substantially in correspondence with the fractured area of the reservoir, a microwave/RF emission antenna connected by means of a waveguide or cable, to a magnetron; and
d. fluidifying the viscous oil distributed in the reservoir by heating it with the heat produced by the microwaves/RF .
According to the present invention, the oil production well can be a vertical or tilted, simple or with one or more branchings which radiate into the reservoir. As is known, the walls of the well, proceeding towards the reservoir, are reinforced with a cylindrical steel structure, called casing, which adheres and is constrained to the walls with cement/mortar or concrete, generally consisting of a mixture of Portland cement and inert aggregates such as siliceous sand and possibly gravel. When the drilling phase of the well is terminated, with the possible formation of one or more branchings, the operative phases are initiated for completing the safety set-up phase of the well and activating the oil production.
When the well enters into production, the oil is recovered by means of a specific tubing, known as production tubing. This is a steel tubing which is
inserted into the well and also into each branching, until it reaches the level of the reservoir. At the well bottom (also in correspondence with each branching) , the tubing is fixed by means of a combined hydraulic and mechanical sealing system, called packer, which forces the oil to rise to the surface from inside the tubing without touching the walls of the casing.
According to the present invention, the terminal part of the casing, downstream of the packer, is made with a cylindrical structure of plastic material, as the organic polymeric materials used as plastic material are much more transparent to microwaves/RF than steel. The dimension of the casing section or segment made of plastic material is substantially determined by the dimension of the reservoir and size of the well. The segment (substantially circular section) generally has a length ranging from 2 to 20 metres and a wall thickness ranging from 1 to 5 cm.
The plastic material can be a thermoplastic polymer or a thermosetting resin. In the former case, a polymer such as polypropylene, polyvinylchloride , polyesters (for example PET, PBT) , thermotropic polyesters, "engineering polymers", polyamides etc., can be used, and in the latter case thermosetting polyester resins or epoxy resins can be used. In both cases, the materials can be reinforced with mineral fillers, such as talc or calcium carbonate, and/or with fibrous material such as glass fibres, carbon fibres, aramidic
fibres, continuous or short.
In order to favour the transparency to microwaves, the terminal section of the casing made of plastic material is fixed to the walls of the well with mortar wherein the inert part essentially consists of alumina (A1203) , which is more transparent to microwaves/RF than silica-based sand.
The part of casing overlying the section made of plastic material is made of steel. The steel part of casing directly above the plastic casing and below the packer in turn comprises the production section, which can be associated with a screen for allowing the oil to flow from the reservoir into the well without producing possible sandy materials, and then rise to the surface through the tubing.
The second step (b) of the process, object of the present invention, envisages injecting into the reservoir, substantially at the bottom of the well, finely subdivided particles of ceramic material having a high thermal conductivity, dispersed in a fluid with a variable viscosity, by means of an induced fracturing operation. The induced fracturing operation is, as a general principle, an operation which is applied in the oil industry, for allowing the oil to flow more easily towards the well. According to the process, object of the present invention, on the other hand, the induced fracturing operation allows the heat generated by the emission of microwaves/RF to be transferred in depth
into the reservoir, by means of fractures which propagate in all directions, and involving, in the heating and fluidification phase, greater volumes of high-viscosity oil with respect to those treated with the methods of the known art .
Induced fracturing is a known technique which envisages subjecting a fluid having a variable viscosity to high pressure at the well bottom so that this can penetrate into the reservoir by means of a fracture in the geological formation in which the reservoir itself is situated. The fluid, which under shear stress has a viscous rheological behaviour, entrains a finely subdivided solid material known as "proppant" which is a preservation agent of fractures. At the end of the fracturing phase, the suspension (viscous fluid + proppant) present in the fractures passes from the shaken state, associated with the shear action of the fracture-creating system, to a rest state during which the viscous fluid tends to have a Newtonian fluid rheological behaviour. As it becomes less viscous, the fluid is slowly absorbed by the reservoir and flow from the fractures diluting in the formation. The proppant, on the other hand, remains in the fractures consolidating them.
Information and details on induced fracturing techniques, on fluids with a variable viscosity and proppants, are available in scientific literature, for example in J.M. McGowen et al . "Fluid Selection for
Fracturing High-Permeability Formations", SPE 26559, 1993, 451-466 or in M.B. Smith et al . "High- Permeability Fracturing: The Evolution of a Technology", JPT, July 1996, 628-633.
According to the present invention, the fluid with a variable viscosity generally consists of a base selected from water, oil, alcohols, etc., in which a substance is dispersed/dissolved, capable of providing the desired rheological fluid behaviour suitable for producing an induced fracture at the well bottom. Examples of these substances are guar rubber or materials of the type CMHPG (Carboxy Methyl Hydroxy Propyl Guar) or CMHEC (Carboxy Methyl Hydroxy Ethyl Cellulose) .
The finely subdivided ceramic solid, which is dispersed in the fluid having a variable viscosity, as a traditional proppant, preferably consists of silicon carbide, SiC, with a particle-size ranging from 1 to 20 μπι, preferably from 1 to 10 μπι. This material is preferred as it allows an optimum diffusion of the heat generated by the microwaves/RF . The concentration of finely subdivided ceramic material, for example SiC, in the suspension varies from 20 to 60% by weight (calculated with respect to the total of fluid + ceramic material), preferably from 30 to 50%. If required, conventional suspending agents (surfactants) can be used, to favour, for example, the re-dispersion of the solid and prevent its accumulation, in the case
of sedimentation of the suspension following prolonged storage .
The choice of silicon carbide is substantially determined by the fact that it is a material with extremely good mechanical properties, among which a high hardness and a high elastic modulus, it has a low density, a low thermal expansion coefficient, an excellent thermal shock resistance and is substantially inert to the chemical products generally present in the reservoir, for example H2S, mercaptans, nitrogenated compounds, C02, etc. In particular, however, the preferred characteristics of silicon carbide are its good absorbing capacity of microwaves/RF and a high thermal conductivity, which enables the heat generated by the microwaves/RF to be transferred in depth in the reservoir.
According to a preferred embodiment of the present invention, the ceramic material, i.e. the silicon carbide, is mixed with stainless steel microbeads, in a quantity ranging from 2 to 10% by weight (calculated with respect to the total of ceramic material + steel microbeads) . As the latter are not transparent to microwaves, they reflect them in all directions improving the diffusion of heat in the fractures and from these towards the reservoir, thus favouring the fluidification of the oil contained therein.
Thanks to the viscosity of the fluid injected at the well bottom, fractures can be obtained, which are
distributed in depth in the geological formation in which the reservoir is present. The fractures can be distributed and developed at 360°, in all directions, with lengths which can be greater than 20 metres, generally ranging from 20 to 50 meters, preferably from 25 to 30 metres.
The part of the well involved in the induced fracturing operation is preferably the terminal part of the casing, which is made of plastic material. In order to allow the induced fracturing generation fluid to penetrate and fracture the formation, the casing made of plastic is previously perforated so that the viscous suspension can flow through the corresponding holes. At the end of the fracturing phase, in order to prevent the crude oil fluidified by the heat generated by the microwaves/RF from entering these holes, at the production regime, the plastic casing is internally covered with a continuous elastic lamina, again made of thermoplastic material, which blocks the holes as it elastically pushes against the internal cylindrical walls. Nothing can prevent, however, the part of the well involved in the induced fracturing operation from being that which corresponds to the production area immediately overlying the plastic casing. If the formation of the reservoir is not consolidated, screens (steel casings with a mesh structure) can be added in front of the production area to prevent the entrainment of sand, or other material of the formation, which
could block the well.
At the end of the induced fracturing phase, the well can enter into production. In order to favour the flow from the reservoir to the well, the viscous oil is heated with the microwaves/RF . In particular, a microwave/RF antenna is lowered to the well bottom, in the bed of the casing made of plastic material, which is capable of irradiating radiofrequencies ranging from 0.1 to 1 GHz or microwaves with frequencies ranging from 1 GHz to 300 GHz and an overall wavelength ranging from 0.001 to 3 metres. The antenna is connected, by- cable or waveguide, to a magnetron having a power ranging from 1 to 5 MW, situated on the surface or inside the well in a specific position.
In the operative phase, the antenna continuously emits microwave beams/RF which are diffused in the formation and reservoir at 360° in all directions. In this overall diffusion phase, the microwaves encounter both the reservoir and the fractures filled with ceramic material, in particular silicon carbide (SiC) and possibly stainless steel microbeads. The electromagnetic waves are absorbed by the SiC and homogeneously reflected by the stainless steel beads in all directions and transformed into heat which is further diffused in the reservoir. In this way, the fractures become further heat sources which penetrate the reservoir allowing greater volumes of viscous oil to be fluidified with respect to those fluidified with
the methods of the known art .
The process for the fluidification of a high- viscosity oil directly inside a reservoir, object of the present invention, can be better understood with reference to the drawing of the enclosed Figure which represents an illustrative and non- limiting embodiment.
In the Figure, the numerical reference (1) indicates the reservoir in which a heavy crude oil is contained. The reference number (2) indicates the steel casing whose terminal part, reference number (3) indicates the screen or "production section or area" .
Below the production section there is the perforated casing made of plastic material, reference number (4) , whereby the induced fracturing operation takes place. The reference number (5) indicates the fractures filled with the thermally conductive ceramic material, for example with Sic, whereas the reference numbers (6) and (7) respectively indicate the antenna for microwaves/RF and the cable or waveguide which connect the antenna to the magnetron, not illustrated in the Figure .
The dashed and compact arrows respectively indicate the microwaves/RF emitted by the antenna, reference number (8) , and the flow of heated and fluidified oil, reference number (9) , which moves from the reservoir towards the production area.
The functioning of the process, object of the present invention, is evident from the above
11000427
description and scheme of the enclosed figure. Under regime conditions, the antenna (6) transmits beams of microwaves or radiofrequencies (8) which are diffused in the reservoir (1) and cause its heating. During this irradiation phase, moreover, the waves also encounter and heat the SiC contained in the fractures (5) . Thanks to its thermal properties, including its thermal conductivity, the SiC can be easily heated and allows the heat to be transferred in depth inside the reservoir. The hot oil which is consequently more fluid (9) can be easily transferred towards the production area (3) to rise into the casing (2) towards the pumping system (not illustrated in the Figure) which will take it to the surface by means of the tubing.
Claims
1. A process for the fluidification of a high- viscosity oil directly inside a reservoir which comprises :
a. producing a well by the drilling of an oil field until reaching the oil reservoir;
b. injecting into the reservoir, substantially at the bottom of the well, finely subdivided particles of ceramic material having a high thermal conductivity, dispersed in a fluid with a variable viscosity, by means of an induced fracturing operation;
c. installing, substantially in correspondence with the fractured area of the reservoir, a RF/microwave emission antenna connected by means of a wave guide or cable, to a magnetron; and
d. fluidifying the viscous oil distributed in the reservoir by heating it with the heat produced by the RF/microwaves .
2. The process according to claim 1, wherein the walls of the well are reinforced with a steel cylindrical structure, called casing, whose terminal part is made with a cylindrical structure of plastic material transparent to RF/microwaves housing the emission antenna of the latter.
3. The process according to claim 2, wherein the plastic material is selected from thermoplastic polymers and thermosetting resins.
4. The process according to any of the previous claims, wherein the terminal section of casing made of plastic material is constrained to the walls of the well by means of mortar comprising alumina (Al203) .
5. The process according to any of the previous claims, wherein the fluid with a variable viscosity generally consists of a base selected from water, oil, alcohols in which a substance is dispersed/dissolved, capable of giving the desired rheological fluid behaviour suitable for producing an induced fracture at the well bottom.
6. The process according to any of the previous claims, wherein the induced fractures are distributed and developed at 360°, in all directions, with lengths greater than 20 metres.
7. The process according to any of the previous claims, wherein the finely subdivided ceramic solid consists of silicon carbide, SiC, with a particle size ranging from 1 to 20 μτη.
8. The process according to any of the previous claims, wherein the concentration of finely subdivided ceramic material in the suspension varies from 20 to 60% by weight, calculated with respect to the total fluid + ceramic material.
9. The process according to any of the previous claims, wherein the ceramic material is mixed with stainless steel micro-beads, in a quantity ranging from 2 to 10% by weight.
10. The process according to any of the previous claims, wherein the antenna for RF/microwaves radiates radiofrequencies from 0.1 to 1 GHz or microwaves with frequencies ranging from 1 GHz to 300 GHz.
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ITMI2010A000273 | 2010-02-22 | ||
ITMI2010A000273A IT1398309B1 (en) | 2010-02-22 | 2010-02-22 | PROCEDURE FOR THE FLUIDIFICATION OF A HIGH VISCOSITY OIL DIRECTLY INSIDE THE FIELD. |
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Cited By (6)
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CN102518420A (en) * | 2011-12-26 | 2012-06-27 | 四机赛瓦石油钻采设备有限公司 | Unlimited-layer electrically controlled fracturing sliding sleeve |
JP2016525177A (en) * | 2013-07-18 | 2016-08-22 | サウジ アラビアン オイル カンパニー | Electromagnetically assisted ceramic materials for heavy oil recovery and on-site steam generation |
CN107420079A (en) * | 2017-09-25 | 2017-12-01 | 西南石油大学 | The exploitation mechanism and method of a kind of dual horizontal well SAGD viscous crude |
US9939421B2 (en) | 2014-09-10 | 2018-04-10 | Saudi Arabian Oil Company | Evaluating effectiveness of ceramic materials for hydrocarbons recovery |
US11619097B2 (en) | 2021-05-24 | 2023-04-04 | Saudi Arabian Oil Company | System and method for laser downhole extended sensing |
US11725504B2 (en) | 2021-05-24 | 2023-08-15 | Saudi Arabian Oil Company | Contactless real-time 3D mapping of surface equipment |
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Publication number | Priority date | Publication date | Assignee | Title |
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CN102518420A (en) * | 2011-12-26 | 2012-06-27 | 四机赛瓦石油钻采设备有限公司 | Unlimited-layer electrically controlled fracturing sliding sleeve |
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CN107420079A (en) * | 2017-09-25 | 2017-12-01 | 西南石油大学 | The exploitation mechanism and method of a kind of dual horizontal well SAGD viscous crude |
US11619097B2 (en) | 2021-05-24 | 2023-04-04 | Saudi Arabian Oil Company | System and method for laser downhole extended sensing |
US11725504B2 (en) | 2021-05-24 | 2023-08-15 | Saudi Arabian Oil Company | Contactless real-time 3D mapping of surface equipment |
Also Published As
Publication number | Publication date |
---|---|
IT1398309B1 (en) | 2013-02-22 |
WO2011101739A3 (en) | 2012-07-05 |
ITMI20100273A1 (en) | 2011-08-23 |
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