CN116624133A - Drainage composite thickened oil exploitation method - Google Patents
Drainage composite thickened oil exploitation method Download PDFInfo
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- CN116624133A CN116624133A CN202210123921.1A CN202210123921A CN116624133A CN 116624133 A CN116624133 A CN 116624133A CN 202210123921 A CN202210123921 A CN 202210123921A CN 116624133 A CN116624133 A CN 116624133A
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- 238000000034 method Methods 0.000 title claims abstract description 41
- 239000002131 composite material Substances 0.000 title claims abstract description 21
- 238000002347 injection Methods 0.000 claims abstract description 99
- 239000007924 injection Substances 0.000 claims abstract description 99
- 239000003921 oil Substances 0.000 claims abstract description 77
- 238000004519 manufacturing process Methods 0.000 claims abstract description 73
- 239000012530 fluid Substances 0.000 claims abstract description 62
- 239000002904 solvent Substances 0.000 claims abstract description 59
- 239000007788 liquid Substances 0.000 claims abstract description 39
- 238000006073 displacement reaction Methods 0.000 claims abstract description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 17
- 238000004891 communication Methods 0.000 claims abstract description 15
- 150000001875 compounds Chemical class 0.000 claims abstract description 11
- 238000012544 monitoring process Methods 0.000 claims abstract description 11
- 239000007789 gas Substances 0.000 claims description 31
- 238000011084 recovery Methods 0.000 claims description 26
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 17
- 239000000295 fuel oil Substances 0.000 claims description 16
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 claims description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 8
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 8
- 238000007599 discharging Methods 0.000 claims description 7
- 238000010793 Steam injection (oil industry) Methods 0.000 claims description 5
- 239000001273 butane Substances 0.000 claims description 5
- 238000005336 cracking Methods 0.000 claims description 5
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical group CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 claims description 5
- 238000013459 approach Methods 0.000 claims description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 4
- 239000001569 carbon dioxide Substances 0.000 claims description 4
- 229920002521 macromolecule Polymers 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 229920006395 saturated elastomer Polymers 0.000 claims description 4
- -1 small molecule compound Chemical class 0.000 claims description 3
- 239000010779 crude oil Substances 0.000 abstract description 19
- 238000010796 Steam-assisted gravity drainage Methods 0.000 abstract description 13
- 238000010795 Steam Flooding Methods 0.000 abstract description 11
- 230000004044 response Effects 0.000 abstract description 2
- 235000019198 oils Nutrition 0.000 description 65
- 238000011161 development Methods 0.000 description 12
- 239000010410 layer Substances 0.000 description 12
- 230000008901 benefit Effects 0.000 description 8
- 230000005484 gravity Effects 0.000 description 8
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- 238000002485 combustion reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
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- 238000005086 pumping Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003027 oil sand Substances 0.000 description 1
- 235000019476 oil-water mixture Nutrition 0.000 description 1
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- 238000004088 simulation Methods 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
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- 238000006467 substitution reaction Methods 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
-
- 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
- E21B43/164—Injecting CO2 or carbonated water
-
- 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
- E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
-
- 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
- E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
- E21B43/168—Injecting a gaseous medium
-
- 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
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
The invention is applicable to the field of thickened oil exploitation, and provides a drainage composite thickened oil exploitation method, which comprises the following steps: establishing a directional communication channel between an injection well and a production well at the bottom of an oil layer; and injecting displacement liquid into the injection well, recovering produced liquid from the production well, monitoring the temperature of the produced liquid of the production well, and when the temperature of the produced liquid reaches a preset temperature, performing displacement compound exploitation, and continuously injecting mixed fluid into the injection well. After the communication is completed, the pressure response among well groups is implemented rapidly, so that the starting efficiency of the SAGD or steam flooding or fire flooding in the early stage of exploitation is improved; reducing oil saturation (hot water displacement) or reducing crude oil viscosity (hot solvent displacement), and maintaining a low-viscosity channel clear; the solvent gathers at the thermal front and is swept towards the production well, the oil displacement efficiency is high, the saturation of residual oil is low, and the oil production speed is high; compared with steam flooding, the bottom oil reservoir can be effectively heated, the lower portion utilization degree is improved, and the oil-gas ratio is improved.
Description
Technical Field
The invention belongs to the field of thick oil exploitation, and particularly relates to a drainage composite thick oil exploitation method.
Background
The world thick oil reserves are huge, and the main current technology of thick oil development is methods such as steam huff and puff, steam flooding, SAGD (steam assisted gravity drainage), fire flooding and the like. Steam flooding is a successor technology of steam huff and puff of a heavy oil reservoir, high-dryness steam is continuously injected into an oil layer by an injection well, and the steam continuously heats the oil layer, so that the viscosity of stratum crude oil is greatly reduced. The injected steam condenses to hot water after releasing latent heat in the formation, driving the crude oil into production wells and being produced. Because the fluidity ratio of steam/hot water to thick oil is large, conventional displacement is poor, steam is easy to break through along the top of an oil layer, and once the steam breaks through, the oil-gas ratio is reduced, and an effective displacement pressure difference cannot be established between wells; in addition, the top of the oil layer is extracted to a very high degree due to the early huff and puff operation, after the steam is driven, the steam cavity is quickly topped, a large amount of high-temperature steam is in long-time contact with the top cover layer, and huge heat loss is caused, so that the economic efficiency is lower. Steam injection development is also accompanied by serious gravity differentiation, obvious steam overburden can be formed, so that residual oil is very low after upper steam displacement, and the middle and lower part of an oil reservoir is relatively low in temperature, high in crude oil viscosity and insufficient in displacement power, so that a large amount of thick oil at the middle and lower part is difficult to extract. SAGD is to deploy double horizontal wells at the bottom of an oil reservoir, continuously inject steam from the upper horizontal well, and continuously produce oil from the lower horizontal well. The steam is continuously expanded upwards under the overburden effect, condensed oil is condensed in a cold oil reservoir, latent heat is released, condensed water and heated crude oil flow to a production well at the lower part under the action of gravity, and under the lifting actions of underground pumping, lifting and the like, an oil-water mixture reaches the ground and is subjected to demulsification oil-water separation, so that ultra-thick oil is obtained. SAGD gives full play to the advantages of strong reservoir control capability and high oil production speed of a horizontal well, combines the advantage of high recovery ratio of the gravity drainage technology, is the main technology for developing super-heavy oil at present, and is widely applied to the development of super-heavy oil and oil sand at home and abroad. Gravity oil drainage forms better liquid resistance and oil-gas ratio is higher than displacement. However, in the middle and later stages, the heated crude oil flows to the production well with great resistance due to the overlarge transverse expansion scale (approximately 50 meters) of the steam cavity, and the effective gravity pressure head gradually decreases, so that the oil production speed is greatly reduced. Finally, a wedge-shaped difficult-to-use zone is left between SAGD well groups, and additional horizontal wells are required to be drilled to strengthen the use. The fireflood uses the heavy components in crude oil as fuel, air as combustion improver, ignition to maintain the combustion of crude oil in oil layer, oxidation reaction to generate great amount of heat, heating of oil layer, cracking of heavy components in crude oil at high temperature to obtain modified light oil, flue gas, water vapor, etc. these fluids together drive crude oil out of oil layer. Has the unique advantages of energy conservation, environmental protection, high heat efficiency and the like.
The successful implementation of the starting is a key step for implementing the thermal recovery of the thick oil, and has great influence on the overall economic benefit of the process technology. For steam flooding and SAGD, the conventional throughput and steam cycle starting method has the defects of low heat utilization, long starting time, high input and output, and the like, and the timing of the flooding is easy to miss. In addition, after the huff and puff start, heat is difficult to be effectively conducted to the bottom of the oil reservoir due to gas overburden, so that the lower part of the oil reservoir is difficult to be used in later steam flooding development. The invention mainly aims at the problems of steam flooding, SAGD and other thermal recovery technologies, and provides a flooding and drainage composite thickened oil recovery method.
Disclosure of Invention
Aiming at the problems, on one hand, the invention discloses a drainage composite thickened oil recovery method, which comprises the following steps:
establishing a directional communication channel between an injection well and a production well at the bottom of an oil layer;
injecting displacement liquid into the injection well, recovering produced liquid from the production well, and monitoring the temperature of the produced liquid of the production well;
when the temperature of the produced liquid reaches a preset temperature, flooding and discharging compound exploitation is carried out, and mixed fluid is continuously injected into the injection well.
Further, after the directional communication channel is established between the injection well and the production well at the bottom of the oil reservoir, the method further comprises:
after the directional communication channel is completed, the pressure among well groups is rapidly responded and implemented, and the liquid flows out from the wellhead of the production well within a specified time.
Further, the displacement liquid is a hot solvent or hot water.
Further, the recovering the produced fluid from the production well specifically includes:
the production well adopts pressure control production, the down-hole flow is lower than the reservoir pressure, and the produced liquid is continuously pumped and recovered from the production well.
Further, the mixed fluid is a mixed fluid of steam and solvent.
Further, when the temperature of the produced fluid reaches the preset temperature, performing flooding and drainage composite production, and continuously injecting the mixed fluid into the injection well specifically includes:
when the temperature of the produced fluid of the production well reaches above a preset temperature, continuously injecting mixed fluid of steam and solvent into the injection well, and monitoring the injection pressure of the injection well in real time;
when the injection pressure increases at a rate exceeding the intervention rate, the solvent content in the mixed fluid is increased, and the recovery of the thick oil is continuously carried out.
Further, the injection pressure is lower than the oil reservoir fracture pressure, and the injection temperature of the mixed fluid is the saturated steam temperature at the injection pressure; on the premise that the injection pressure is lower than the cracking pressure, the injection flow and the steam dryness of the mixed fluid are gradually improved, and the expansion of the steam cavity is accelerated.
Further, when the injection pressure increases at a rate exceeding the intervention rate, the solvent content in the mixed fluid is increased, the solvent is mainly a macromolecular compound, and the solvent is in a liquid state under the operating condition.
Further, when the injection pressure increases at a rate exceeding the intervention rate, the solvent content in the mixed fluid is increased, and after the recovery of the thick oil is continued, the method further comprises:
when the fluctuation of injection pressure is in a stable region, the solvent in the mixed fluid is changed into a small molecular compound solvent.
Further, the small molecule compound solvent is butane or hexane or pentane.
Further, when the temperature of the produced fluid reaches the preset temperature, the flooding and drainage composite production is performed, and after the mixed fluid is continuously injected into the injection well, the method further comprises:
injecting non-condensing gas into the injection well when the steam cavity near the injection well has risen to the top, and monitoring the oil-gas ratio of the produced liquid;
when the oil-gas ratio of the recovered produced liquid is reduced to a preset low value, the flooding composite exploitation approaches tail sound, the steam injection into the injection well is stopped, and the non-condensable gas is continuously injected for displacement.
Further, the non-condensable gas is injected into the injection well in a slug or a satellite injection mode.
Further, the non-condensable gas is nitrogen or methane or carbon dioxide.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides the following components.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 shows a schematic diagram of a flooding collaborative development of an embodiment of the present invention;
FIG. 2 shows temperature field profiles at various stages of an embodiment of the invention;
FIG. 3 shows a graph of oil saturation change at various stages of an embodiment of the present invention;
FIG. 4 shows a graph of differential pressure between injection and production horizontal wells according to an embodiment of the present invention;
FIG. 5 shows a concentration profile of a solvent in the gas phase for an embodiment of the present invention;
FIG. 6 is a graph showing the extent of extraction as a function of time for an embodiment of the present invention;
FIG. 7 shows a graph of cumulative oil-to-gas ratio over time for an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In one embodiment of the invention, the thickened oil recovery method comprises:
establishing a directional communication channel between an injection well and a production well at the bottom of an oil layer;
injecting displacement liquid into the injection well, recovering produced liquid from the production well, and monitoring the temperature of the produced liquid of the production well; the displacement liquid is a hot solvent or hot water.
When the temperature of the produced liquid reaches a preset temperature, flooding and discharging compound exploitation is carried out, and mixed fluid is continuously injected into the injection well. The mixed fluid is a mixed fluid of steam and solvent.
In one aspect of this embodiment, after the establishing a directional communication channel between the injection well and the production well at the bottom of the reservoir, the method further comprises:
after the directional communication channel is completed, the pressure among well groups is rapidly responded and implemented, and the liquid flows out from the wellhead of the production well within a specified time.
In one aspect of this embodiment, the recovering the produced fluid from the production well specifically comprises:
the production well adopts pressure control production, the down-hole flow is lower than the reservoir pressure, and the produced liquid is continuously pumped and recovered from the production well.
In an embodiment of the present invention, when the temperature of the produced fluid reaches a preset temperature, performing flooding and drainage composite production, and continuously injecting the mixed fluid into the injection well specifically includes:
when the temperature of the produced fluid of the production well reaches above a preset temperature, continuously injecting mixed fluid of steam and solvent into the injection well, and monitoring the injection pressure of the injection well in real time; the injection pressure is lower than the oil reservoir fracture pressure, and the injection temperature of the mixed fluid is the saturated steam temperature at the injection pressure; on the premise that the injection pressure is lower than the cracking pressure, the injection flow and the steam dryness of the mixed fluid are gradually improved, and the expansion of the steam cavity is accelerated.
When the injection pressure increases at a rate exceeding the intervention rate, the solvent content in the mixed fluid is increased, and the recovery of the thick oil is continuously carried out. The solvent is mainly macromolecular compounds and is liquid under the operating condition. When the fluctuation of injection pressure is in a stable region, the solvent in the mixed fluid is changed into a small molecular compound solvent. The small molecule compound solvent is butane or hexane or pentane.
In one embodiment of the present invention, when the temperature of the produced fluid reaches the preset temperature, the flooding compound production is performed, and after the mixed fluid is continuously injected into the injection well, the method further includes:
injecting non-condensing gas into the injection well when the steam cavity near the injection well has risen to the top, and monitoring the oil-gas ratio of the produced liquid;
when the oil-gas ratio of the recovered produced liquid is reduced to a preset low value, the flooding composite exploitation approaches tail sound, the steam injection into the injection well is stopped, and the non-condensable gas is continuously injected for displacement. The non-condensable gas is nitrogen or methane or carbon dioxide.
In one case of this embodiment, the non-condensable gas is injected into the injection well in a slug or a satellite injection manner.
In the actual operation process, as shown in fig. 1, the implementation steps of the drainage composite thickened oil recovery method are as follows:
1. firstly, extracting and injecting solvent/water, and establishing a directional communication channel (directional solvent zone) between wells at the bottom of an oil layer by utilizing solvent fingering (injecting solvent)/geomechanical expansion (water). After the communication is completed, the pressure response between the well groups is rapid (the time delay is less than 2 hours), the sign that the injected solvent/water is produced from the other well is obviously visible, and the starting efficiency of the SAGD or steam flooding or fire flooding in the early stage of exploitation is improved; the solvent is miscible with crude oil, and the viscosity of the formed mixture is greatly reduced to below 100 cP; the solvent may be pure hydrocarbon or other compound, or may be a mixture of compounds.
2. And injecting hot solvent or hot water into the injection well, adopting pressure-controlled production in the production well, continuously pumping the production well from the production well under the condition that the downhole flowing pressure is slightly lower than the reservoir pressure, increasing the temperature of the bottom directional communication channel, simultaneously reducing the oil saturation (hot water displacement) or the viscosity of crude oil (hot solvent displacement), and maintaining the smoothness of the low-viscosity channel.
3. And continuously injecting mixed fluid of steam and solvent into the injection well, and performing flooding and drainage synergistic composite development. When the production well production fluid temperature reaches above 70 ℃ (depending on the viscosity-temperature characteristics of the crude oil), in turn, a mixed fluid of steam and solvent is continuously injected into the injection well. The injection pressure is below the reservoir fracture pressure and the injection temperature of the mixed fluid is the saturated steam temperature at that pressure. On the premise that the injection pressure is lower than the cracking pressure, the injection flow and the steam dryness can be gradually improved, and the expansion of the steam cavity is accelerated. When the injection pressure rises faster, the solvent content should be increased; wherein the solvent is mainly macromolecular compound and is liquid under the operating condition.
Because the steam upwards covers the development steam cavity, most crude oil is heated, the viscosity is greatly reduced, and the crude oil is converged to the bottom flow channel under the action of gravity. Meanwhile, the injected liquid solvent has high density and weak overburden capacity, and also flows into the flow channel to be mixed with crude oil, so that the viscosity is reduced, and the smoothness of the flow channel is ensured. Fluid entering the flow channel flows to the production well under the drive of pressure difference between the injection well and the production well, and is produced.
In the whole drive-release collaborative development process, a liquid seal similar to SAGD is formed on a bottom channel, steam production is prevented, heat transfer efficiency is improved, heat transfer (heated crude oil, condensed water, solvent and other mixed fluid discharged from the upper part) is carried out to a bottom oil reservoir, the use of the lower part of an oil reservoir is greatly enhanced, steam wave and recovery ratio is improved, and oil-gas ratio is improved.
4. Continuous injection production does not see significant pressure fluctuations (injection pressure rise over 40% of operating pressure) and is shifted to continuous injection of steam with small molecule solvents (such as butane, hexane, pentane, etc., which can enter the reservoir in the gas phase when injected in admixture with steam and accumulate or condense at the front of the steam cavity). The auxiliary flooding and discharging of the solvent are cooperated, steam and small molecular solvents (such as butane, hexane, pentane and the like) are continuously injected, the substances can enter the oil reservoir in a gas phase form when being mixed with the steam for injection, and are gathered or condensed at the front edge of a steam cavity, and the solvents are gathered at the hot front edge and are swept towards a production well, so that the flooding efficiency is effectively improved, the saturation of residual oil is reduced, and meanwhile, the oil production speed is increased.
5. When the steam cavity near the injection well is judged to be raised to the top (the monitoring of the observation well or the judgment of other numerical simulation means), non-condensed gases such as nitrogen, methane, carbon dioxide and the like are injected in a slug or concomitant injection mode, the temperature of the steam at the top is reduced to be lower than the saturation temperature of the steam by utilizing the non-condensed gases, the heat loss to the cover layer is greatly reduced, and the heat energy utilization efficiency is improved; along with the progress of the development process of the displacement and leakage cooperation, the temperature of the bottom displacement channel and the temperature nearby the bottom displacement channel are gradually increased, so that the lower portion of the oil reservoir is enhanced, and the displacement and leakage composite production degree is improved.
6. When the oil-gas ratio is obviously reduced, the displacement and the leakage are cooperatively developed to approach tail sound, steam injection is stopped, non-condensed gas is continuously injected for displacement, the fluid in the oil reservoir is continuously produced, the solvent is recovered, and the saturation of residual oil is reduced.
The thickened oil exploitation method can improve the starting efficiency of SAGD, steam flooding and fireflooding in the early exploitation stage; compared with SAGD, the method has the advantages that no wedge-shaped difficult-to-use area exists (the distance from a production well is far, the gravity pressure head is insufficient for providing economic production speed), the scope of the wave is large, and the production degree is high; compared with steam flooding, the bottom oil reservoir can be effectively heated, the lower part utilization degree is improved, and the oil-gas ratio is improved; the method is insensitive to the interlayer and can be used for the development of heterogeneous reservoirs; the total temperature of the produced liquid is low, and the heat energy utilization rate is high; the fuel-gas ratio is high, the energy consumption can be greatly reduced, and the economic efficiency is improved.
When the heavy oil recovery method is implemented, the injection well group is arranged at the lower part of the oil reservoir and is 0.5-1 m away from the bottom boundary, and the gravity pressure head is fully utilized for production; the injection well groups are all horizontal wells, and the length is 200-1000 meters (depending on the geological conditions of the oil reservoir); well spacing is 35-70 meters (depending on factors such as crude oil viscosity, permeability, etc.).
In order to verify the feasibility of the thick oil exploitation method, the method provided by the invention is applied to numerically simulate the development process of a thick oil reservoir. Model size: porosity Φ=0.352, permeability k=120d, oil saturation so= 0.9087. The initial pressure of the oil reservoir is 4MPa, and the temperature of the stratum is 26 ℃. Viscosity of the crude oil was degassed at 50℃to 1500mPaS. The injection and production horizontal wells are all arranged at the bottom of the model and are 1cm away from the bottom boundary, the horizontal section is 25cm long, and the diameter of the well hole is 0.5cm. The well spacing was 48cm. Temperature and pressure measuring points are arranged in the model.
In the simulated exploitation experiment, fluid communication between injection and production wells is formed first, then hot water is injected for displacement, the rate is 75ml/min, the injection temperature is 260 ℃, and the operation pressure is 4MPa.
And then steam-solvent mixed injection and flooding and discharging compound development are carried out. In this process, as shown in fig. 2 and 3, the temperature field and the oil saturation field are respectively distributed in a typical stage, the stages represented by three arranged pictures in the two figures correspond to the hot water injection ending stage, the steam-solvent mixed fluid medium stage and the steam-solvent mixed fluid end stage from top to bottom, and the arrow starting points on the left and right sides in the figures respectively represent the positions of the production well and the injection well. In the experiment, the solvent is n-hexane, the molar concentration is 30%, the temperature of the injected mixed fluid is 260 ℃, the operation pressure is 4MPa, and the duration is 120min. As shown in fig. 2, it was observed in the experiment that the top temperature of the model was continuously lower than the steam saturation temperature, greatly reducing the top heat dissipation. Meanwhile, the temperature of the production well is lower, the temperature of the early stage of the experiment is about 50 ℃, the later stage is expanded along with the expansion of the air cavity, when the front edge is pushed to the vicinity of the production well, the temperature of the produced fluid rises to about 160 ℃, and the total produced temperature is greatly lower than the SAGD and steam drive produced fluid temperature under the same operating temperature and pressure condition, which indicates that the heat carried by the production is effectively reduced, and the heat utilization efficiency is further improved.
As shown in FIG. 4, the pressure difference between the injection and production wells in the early stage is larger and reaches 60KPa, and the pressure difference in the later stage is reduced to be within 1KPa along with the rise of the temperature of the produced fluid. As shown in fig. 5, the starting points of the arrows on the left and right sides of the graph represent the positions of the production well and the injection well respectively, and the accumulation of the solvent at the front of oil drainage is observed in the experiment to form solvent displacement, so that the saturation of the residual oil is greatly reduced. As shown in fig. 3, as the solvent is injected, the residual oil saturation decreases, and at the end of injection production, the residual oil saturation is as low as 0.08. As in fig. 6 and 7, the experiment ended at about 300 minutes with a recovery of 80% and an accumulated oil vapor ratio of greater than 0.6.
Although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (13)
1. A method for recovering thickened oil by composite drainage, which is characterized by comprising the following steps:
establishing a directional communication channel between an injection well and a production well at the bottom of an oil layer;
injecting displacement liquid into the injection well, recovering produced liquid from the production well, and monitoring the temperature of the produced liquid of the production well;
when the temperature of the produced liquid reaches a preset temperature, flooding and discharging compound exploitation is carried out, and mixed fluid is continuously injected into the injection well.
2. The drainage composite heavy oil recovery method of claim 1, wherein after establishing a directional communication channel between the bottom of the reservoir, the injection well and the production well, the method further comprises:
after the directional communication channel is completed, the pressure among well groups is rapidly responded and implemented, and the liquid flows out from the wellhead of the production well within a specified time.
3. The flooding complex heavy oil recovery method of claim 2, wherein the displacement liquid is a hot solvent or hot water.
4. The flooding complex thickened oil recovery method of claim 1, wherein recovering produced fluid from a production well specifically comprises:
the production well adopts pressure control production, the down-hole flow is lower than the reservoir pressure, and the produced liquid is continuously pumped and recovered from the production well.
5. The flooding complex heavy oil recovery method of claim 1, wherein the mixed fluid is a mixed fluid of steam and solvent.
6. The method for producing heavy oil by flooding and discharging composite according to claim 5, wherein when the temperature of the produced fluid reaches a preset temperature, the step of producing by flooding and discharging composite is performed, and the step of continuously injecting the mixed fluid into the injection well comprises the following steps:
when the temperature of the produced fluid of the production well reaches above a preset temperature, continuously injecting mixed fluid of steam and solvent into the injection well, and monitoring the injection pressure of the injection well in real time;
when the injection pressure increases at a rate exceeding the intervention rate, the solvent content in the mixed fluid is increased, and the recovery of the thick oil is continuously carried out.
7. The flooding complex heavy oil recovery method of claim 6, wherein the injection pressure is lower than the reservoir fracture pressure, and the injection temperature of the mixed fluid is the saturated steam temperature at the injection pressure; on the premise that the injection pressure is lower than the cracking pressure, the injection flow and the steam dryness of the mixed fluid are gradually improved, and the expansion of the steam cavity is accelerated.
8. The flooding complex heavy oil recovery method of claim 6, wherein when the injection pressure increases at a rate exceeding the intervention rate, the solvent is predominantly macromolecular compounds and is liquid under operating conditions when the solvent content in the mixed fluid is increased.
9. The flooding complex heavy oil recovery method of claim 6, wherein said increasing the rate of injection pressure exceeds the intervention rate increases the solvent content of the mixed fluid, and wherein after continuing to recover heavy oil, said method further comprises:
when the fluctuation of injection pressure is in a stable region, the solvent in the mixed fluid is changed into a small molecular compound solvent.
10. The flooding complex heavy oil recovery method of claim 9, wherein the small molecule compound solvent is butane or hexane or pentane.
11. The drainage composite heavy oil recovery method according to any one of claims 1 to 10, wherein when the temperature of the produced fluid reaches a preset temperature, drainage composite recovery is performed, and after continuously injecting the mixed fluid into the injection well, the method further comprises:
injecting non-condensing gas into the injection well when the steam cavity near the injection well has risen to the top, and monitoring the oil-gas ratio of the produced liquid;
when the oil-gas ratio of the recovered produced liquid is reduced to a preset low value, the flooding composite exploitation approaches tail sound, the steam injection into the injection well is stopped, and the non-condensable gas is continuously injected for displacement.
12. The method for producing heavy oil by combining drainage and recovery according to claim 11, wherein the injection of the non-condensable gas into the injection well is performed by means of a slug or a satellite injection.
13. The flooding complex heavy oil recovery method of claim 11, wherein said non-condensable gas is nitrogen or methane or carbon dioxide.
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