CN112554855A - Method for improving oil recovery ratio by continuous phase composite oil displacement - Google Patents
Method for improving oil recovery ratio by continuous phase composite oil displacement Download PDFInfo
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- 238000011084 recovery Methods 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000006073 displacement reaction Methods 0.000 title claims description 22
- 239000002131 composite material Substances 0.000 title description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 116
- 239000000243 solution Substances 0.000 claims abstract description 94
- 239000007924 injection Substances 0.000 claims abstract description 67
- 238000002347 injection Methods 0.000 claims abstract description 67
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 50
- GHMLBKRAJCXXBS-UHFFFAOYSA-N resorcinol Chemical compound OC1=CC=CC(O)=C1 GHMLBKRAJCXXBS-UHFFFAOYSA-N 0.000 claims description 50
- 235000019270 ammonium chloride Nutrition 0.000 claims description 25
- WYYQVWLEPYFFLP-UHFFFAOYSA-K chromium(3+);triacetate Chemical compound [Cr+3].CC([O-])=O.CC([O-])=O.CC([O-])=O WYYQVWLEPYFFLP-UHFFFAOYSA-K 0.000 claims description 25
- 229920002401 polyacrylamide Polymers 0.000 claims description 25
- MRUAUOIMASANKQ-UHFFFAOYSA-N cocamidopropyl betaine Chemical compound CCCCCCCCCCCC(=O)NCCC[N+](C)(C)CC([O-])=O MRUAUOIMASANKQ-UHFFFAOYSA-N 0.000 claims description 23
- 229940073507 cocamidopropyl betaine Drugs 0.000 claims description 23
- 239000002994 raw material Substances 0.000 claims description 23
- 239000003208 petroleum Substances 0.000 claims description 21
- 230000015271 coagulation Effects 0.000 claims description 6
- 238000005345 coagulation Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 abstract description 6
- 238000000605 extraction Methods 0.000 abstract description 5
- 230000008859 change Effects 0.000 abstract description 3
- 229920006037 cross link polymer Polymers 0.000 abstract description 2
- 239000004094 surface-active agent Substances 0.000 abstract description 2
- 238000010521 absorption reaction Methods 0.000 abstract 1
- 239000003921 oil Substances 0.000 description 99
- 239000010779 crude oil Substances 0.000 description 31
- 239000003129 oil well Substances 0.000 description 23
- 230000000694 effects Effects 0.000 description 11
- 230000001965 increasing effect Effects 0.000 description 10
- 239000011435 rock Substances 0.000 description 8
- 239000009096 changqing Substances 0.000 description 7
- 238000012360 testing method Methods 0.000 description 5
- 230000000903 blocking effect Effects 0.000 description 4
- 230000001112 coagulating effect Effects 0.000 description 3
- -1 i.e. Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- ROSDSFDQCJNGOL-UHFFFAOYSA-N Dimethylamine Chemical compound CNC ROSDSFDQCJNGOL-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000000701 coagulant Substances 0.000 description 2
- 238000004132 cross linking Methods 0.000 description 2
- 239000003431 cross linking reagent Substances 0.000 description 2
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- 239000012530 fluid Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000002888 zwitterionic surfactant Substances 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/58—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
- C09K8/584—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids characterised by the use of specific surfactants
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/58—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
- C09K8/588—Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids characterised by the use of specific polymers
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/602—Compositions for stimulating production by acting on the underground formation containing surfactants
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/84—Compositions based on water or polar solvents
- C09K8/86—Compositions based on water or polar solvents containing organic compounds
- C09K8/88—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
- C09K8/882—Compositions based on water or polar solvents containing organic compounds macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
Abstract
The invention provides a method for improving oil recovery ratio by continuous phase complex flooding, which comprises the steps of injecting weak gel solution into an oil reservoir through a water injection well to improve oil-water fluidity ratio of the oil reservoir, plugging a high-permeability reservoir and enabling oil in the reservoir to flow to a production well more; and secondly, after the cross-linked polymer is injected, injecting a surfactant solution into the same water injection well to reduce the oil-water interfacial tension, separating oil from water, and allowing the oil to enter a production well for extraction. The method can increase the viscosity of water, reduce the water-oil mobility ratio, adjust the water absorption profile of the stratum, reduce the tension of an oil-water interface, change the edge wettability and reduce the pressure of a water injection well.
Description
Technical Field
The invention relates to the technical field of crude oil recovery, in particular to a method for improving the oil recovery rate by continuous phase complex oil displacement.
Background
Crude oil, i.e., petroleum, also known as "black gold", is conventionally referred to as crude oil produced directly from an oil well as raw petroleum, which is a dark brown or dark green viscous liquid or semi-solid combustible substance composed of various hydrocarbons.
In the development stage of oil field in China, water injection and oil displacement are carried out, and after long-time water injection, the oil field is basically produced in three exploitation stages of high water content, ultrahigh water content and medium-low water content at present, and in order to excavate the residual oil in the three stages, a technical method for improving the recovery ratio of crude oil is often adopted. The level of recovery is related to many factors, not only to the natural conditions of reservoir lithology, physical properties, heterogeneity, fluid properties, and drive type, but also to the development scheme adopted in developing the oil field.
Generally, the method for recovering the crude oil mainly aims at improving the sweep efficiency and the oil displacement efficiency, the conventional profile control of the water injection well mainly aims at improving the sweep efficiency of injected water, the improvement effect on the oil displacement efficiency is not obvious or no good method is provided, and the crude oil recovery efficiency cannot be further improved.
At present, oil exploitation basically belongs to a water injection later stage exploitation stage, in the stage, oil in a pore passage in some oil reservoirs is basically displaced, the pore passages are water mixing passages, namely high permeable layers, water injection at later stage enters an oil well along the water mixing passages and cannot enter the low permeable layers to displace the oil in the low permeable layers to the oil well, so that the water mixing passages are generally blocked by weak gel solution at present, and the oil is further ensured to smoothly enter the low permeable layers to displace the oil to the oil well by later stage water injection; in addition, in the later stage of water injection exploitation, oil in the formation gap is basically displaced, a few oil films are left to be attached to the surface of the rock, and if water injection is continued, the oil films attached to the surface of the rock cannot be displaced, adsorbed and transported by water according to the fluid principle.
However, the existing weak gel solution needs long time for solidification and gel formation, has unstable performance in the stratum and is easy to dehydrate and break, so the effective period of the conventional oil production method using the existing weak gel solution is generally less than one year, the effective period of the conventional method for improving the oil recovery ratio is generally less than one year by combining field mine tests, and the maximum effective period is generally 400 days according to the water shutoff and profile control effect evaluation method of the Changqing oil field, so that the improvement of the oil recovery ratio is influenced.
Therefore, it is desirable to provide a method for improving the sweep efficiency of reservoir crude oil, as well as improving the oil displacement efficiency.
Disclosure of Invention
The invention aims to provide a method for improving the oil recovery rate by continuous phase complex oil displacement, which mainly improves the sweep efficiency of injected water and the oil displacement efficiency from the angles of increasing the viscosity of water, reducing the water-oil fluidity ratio, inhibiting the finger advance and the sudden advance of water, reducing the tension of an oil-water interface, improving the wettability, reducing the pressure of a water injection well and the like so as to improve the recovery rate.
The technical scheme for realizing the purpose of the invention is as follows:
in a first aspect, the invention provides a method for improving oil recovery rate by continuous phase complex flooding, which comprises the following steps,
1) preparing weak gel solution, injecting the weak gel solution into the petroleum layer of the corresponding perforation section through the oil pipe of the water injection well, enabling the weak gel solution to enter a water-mixing channel in the petroleum reservoir,
the effective components of the weak gel solution comprise 4 raw materials of polyacrylamide, chromium acetate, resorcinol and ammonium chloride, and the mass fractions of the 4 raw materials are as follows:
0.12-0.22% of polyacrylamide, 0.18-0.3% of chromium acetate, 0.001-0.002% of resorcinol and 0.02-0.04% of ammonium chloride;
2) after the injection of the weak gel solution is finished, closing the well for waiting coagulation, and waiting for the weak gel solution to coagulate into gel;
3) the method comprises the steps of preparing the cocamidopropyl betaine solution with the mass fraction of 0.1-1.0%, injecting the solution into a water injection well through an injection pump, and enabling the solution to enter a petroleum reservoir through a perforation section of the water injection well.
Preferably, the method also comprises the step 4) of injecting water into the water injection well oil pipe through a water injection pump, wherein the volume of the injected water is slightly larger than that of the water injection well oil pipe.
Preferably, the mass fractions of polyacrylamide, chromium acetate, resorcinol and ammonium chloride in step 1) are 0.15%, 0.20%, 0.015% and 0.03%, respectively.
Preferably, the mass fraction of the cocamidopropyl betaine solution is 0.5-0.6%.
In a second aspect, the invention provides a weak gel solution for improving reservoir oil recovery efficiency, wherein the effective components of the weak gel solution comprise 4 raw materials of polyacrylamide, chromium acetate, resorcinol and ammonium chloride, and the mass fractions of the 4 raw materials are as follows:
0.12-0.22% of polyacrylamide, 0.18-0.3% of chromium acetate, 0.001-0.002% of resorcinol and 0.02-0.04% of ammonium chloride.
Preferably, the mass fractions of polyacrylamide, chromium acetate, resorcinol and ammonium chloride are 0.15%, 0.20%, 0.015% and 0.03%, respectively.
The invention has the advantages that:
the invention improves the recovery ratio of the crude oil by simultaneously improving the sweep efficiency and the oil displacement efficiency. Firstly, weak gel solution is injected, the weak gel solution prepared by the method can increase the viscosity of water, reduce the water-oil flow ratio, inhibit the finger-in and the sudden-in of water, adjust the water-absorbing homogeneity of each layer with bad property, has short gel time and stable performance in the stratum, is not easy to break gel, has good effect of blocking a water channel and long blocking duration, can block injected water for a long time, and can displace oil with a low permeable layer into an oil well to the maximum extent by later stage water injection, thereby improving the sweep efficiency and further improving the crude oil recovery ratio;
in addition, when the cocamidopropyl betaine solution is injected, as the cocamidopropyl betaine is a zwitterionic surfactant, the cocamidopropyl betaine solution is diffused in a displacement water phase and reaches an oil-water interface, the oil-water interface tension is improved, the ultralow interface tension is formed, when the interface tension is low enough, the capillary force of an oil film captured on a rock is weakened, the oil film falls off from the surface of the rock to form oil drops, and the oil drops can flow under the action of viscous force and gravity to reduce the saturation of residual oil and then enter an oil well to achieve the purpose of oil displacement; when the residual crude oil is brought out along with the cocamidopropyl betaine solution, the water injection pressure of the oil field with medium and low water content is reduced at the same time, so that the injected cocamidopropyl betaine solution can replace an oil film attached to the surface of the rock, and further the oil displacement efficiency is improved.
Detailed Description
The present invention is described in detail with reference to the following embodiments, but it should be understood that these embodiments are not intended to limit the present invention, and those skilled in the art should understand that the functional, method, or structural equivalents of these embodiments or substitutions may be made without departing from the scope of the present invention.
In a first aspect, the embodiments of the present invention provide a method for increasing oil recovery by continuous phase complex flooding, including the following steps,
1) preparing weak gel solution, injecting the weak gel solution into the petroleum layer of the corresponding perforation section through the oil pipe of the water injection well, enabling the weak gel solution to enter a water-mixing channel in the petroleum reservoir,
the effective components of the weak gel solution comprise 4 raw materials of polyacrylamide, chromium acetate, resorcinol and ammonium chloride, and the mass fractions of the 4 raw materials are as follows: 0.12-0.22% of polyacrylamide, 0.18-0.3% of chromium acetate, 0.001-0.002% of resorcinol and 0.02-0.04% of ammonium chloride;
2) after the injection of the weak gel solution is finished, closing the well to wait for coagulation, and waiting for the weak gel solution to coagulate into gel (generally forming gel for two days);
3) the method comprises the steps of preparing the cocamidopropyl betaine solution with the mass fraction of 0.1-1.0%, injecting the solution into a water injection well through an injection pump, and enabling the solution to enter a petroleum reservoir through a perforation section of the water injection well.
Specifically, the mass fraction of the cocamidopropyl betaine solution is preferably 0.5-0.6%;
the mass fractions of polyacrylamide, chromium acetate, resorcinol and ammonium chloride are preferably 0.15%, 0.20%, 0.015% and 0.03%, respectively.
Combining the indoor test analysis result and the field test effect, when the mass fractions of the 4 raw materials are as follows: 0.12-0.22% of polyacrylamide, 0.18-0.3% of chromium acetate, 0.001-0.002% of resorcinol and 0.02-0.04% of ammonium chloride, compared with the weak gel solution in the prior art, the weak gel solution has short gel time, stable performance in the stratum and difficult gel breakage, so the plugging and water crossing channel has good effect and long plugging duration, thus being capable of plugging injected water for a long time and improving the oil recovery,
when the mass fraction of the cocamidopropyl betaine solution is 0.1-1.0%, the cocamidopropyl betaine solution can diffuse in a displacement water phase and reach an oil-water interface, the oil-water interface tension is improved, when the interface tension is low enough, the capillary force of an oil film captured on a rock is weakened, the oil film falls off from the surface of the rock to form oil drops, the oil drops enter an oil well, the oil displacement efficiency is improved, and the oil recovery is further improved;
when the optimal scheme is adopted for the mass fractions of 4 raw materials of polyacrylamide, chromium acetate, resorcinol and ammonium chloride and the cocamidopropyl betaine solution, the weak gel solution has shorter gel time, more stable performance in the stratum and less possibility of gel breaking, so that the effect of blocking a water crossing channel is better, the blocking duration is longer, injected water can be blocked more durably, and the oil recovery is improved to a greater extent; the cocamidopropyl betaine solution can better improve the oil-water interfacial tension, further improve the oil displacement efficiency and improve the oil recovery.
Generally, the oil extraction is carried out by adopting the optimal scheme of the invention, the oil extraction amount is greatly improved, and the effect is obvious.
Crude oil was recovered by injecting weak gel solution and cocamidopropyl betaine solution into the water injection well. The cross-linked polymer is weak gel formed by cross-linking 4 raw materials, and the 4 raw materials are 1 polymer, 2 organic cross-linking agents and 1 coagulant. The polymer is polyacrylamide, the 2 kinds of organic cross-linking agents are chromium acetate and resorcinol, and the coagulant is ammonium chloride. For an oil well with three exploitation stages of high water content, ultrahigh water content and medium-low water content, a stratum environment is in a high-salinity water solution, the dehydration and gel breaking time of a weak gel solution in the high-salinity water is prolonged, the weak gel is prevented from undergoing a chemical reaction with metal ions in the stratum to form a new substance, the chemical property is changed, dehydration and gel breaking are caused due to unstable performance, and further a water crossing channel cannot be plugged, and the proportion of raw materials in the weak gel solution 4 enables the prepared weak gel solution to have stable performance, so that the water crossing channel can be plugged more effectively, and the swept efficiency is improved;
wherein the cocamidopropyl betaine is a zwitterionic surfactant, the cocamidopropyl betaine solution is aqueous solution of cocamidopropyl dimethylamine ethylene lactone, and the molecular formula of the cocamidopropyl dimethylamine ethylene lactone is [ RCONH (CH)2)3N+(CH3)2CH2COO- "is from plant, is a complex macromolecule organic matter, has excellent stability under acidic and alkaline conditions, presents positive and negative ion respectively, is easily soluble in water, has higher viscosity, has no irritation or toxic and side effects, has high safety performance, is easy to biodegrade, and has good compatibility. The surface activity of the oil-bearing slurry is utilized to infiltrate, permeate and strip crude oil in the oil-bearing slurry, so that the recovery ratio of the third recovery is improved. According to field tests, when the concentration of the cocamidopropyl betaine solution is 0.3-1.0%, the effect of improving the oil recovery and displacement efficiency of crude oil is optimal.
In order to avoid waste of raw materials, the method also comprises the step 4) of injecting water into the oil pipe of the water injection well through a water injection pump, wherein the volume of the injected water is slightly larger than that of the oil pipe of the water injection well, and the residual cocamidopropyl betaine solution in the oil pipe of the water injection well is extruded into the oil reservoir through the injected water. And (4) directly entering an oil extraction stage after the step (3) is finished, and specifically injecting water into an oil pipe of the water injection well by using a water injection pump for oil extraction, wherein the water injection amount is not limited by requirements.
The principle of crude oil recovery of the invention is as follows:
according to the invention, the crude oil recovery adopts the organic cross-linked weak gel formed by 4 raw materials to plug a water crossing channel in a petroleum reservoir, and the surfactant of cocamidopropyl dimethylamine caprolactone is matched for use, so that the oil-water interfacial tension is improved, the ultralow interfacial tension is formed, an oil film falls off from the surface of a rock and then enters an oil well in the form of oil drops, and the oil displacement efficiency of crude oil is improved under the condition of improving the recovery efficiency of the crude oil, so that the recovery efficiency of the crude oil is greatly improved.
In a second aspect, the invention provides a weak gel solution for improving reservoir oil recovery efficiency, wherein the effective components of the weak gel solution comprise 4 raw materials of polyacrylamide, chromium acetate, resorcinol and ammonium chloride, and the mass fractions of the 4 raw materials are as follows: 0.12-0.22% of polyacrylamide, 0.18-0.3% of chromium acetate, 0.001-0.002% of resorcinol and 0.02-0.04% of ammonium chloride;
preferably, the mass fractions of polyacrylamide, chromium acetate, resorcinol and ammonium chloride are 0.15%, 0.20%, 0.015% and 0.03%, respectively.
The technical parameters of the weak gel formed by the cross-linking reaction of 4 raw materials of polyacrylamide, chromium acetate, resorcinol and ammonium chloride are as follows: the viscosity of the weak gel solution is less than or equal to 100 mPa.s; the weak gel solution is formed for 6-48 h; the colloid viscosity of the weak gel is more than or equal to 30000 mPa.s; the viscosity change rate of the weak gel is less than +/-5.0%. Preferably, the viscosity in the weak gel is 24 mPa.s; the weak gel solution is formed for 24 hours; the weak gel had a colloidal viscosity of 35900 mpa.s; when the viscosity change rate of the weak gel is 1.5%, the weak gel has the best effect on improving the sweep efficiency of crude oil recovery.
The method for improving the oil displacement rate is described in detail by the following specific embodiments:
example 1:
in this embodiment, a hu 154 block hu 171 well group constructed in the Changqing oil field in 12 months in 2018 is taken as an example for introduction, and crude oil recovery of the hu 171 well group includes the following steps:
1) preparing weak gel solution, wherein the mass fractions of 4 raw materials of the weak gel solution are 0.15 percent of polyacrylamide, 0.20 percent of chromium acetate, 0.015 percent of resorcinol and 0.03 percent of ammonium chloride; injecting the prepared weak gel solution into a petroleum layer of a corresponding perforation section through an oil pipe of the water injection well, wherein the weak gel solution enters a water-mixing channel in the petroleum reservoir;
2) after the injection of the weak gel solution is finished, closing the well for coagulation, waiting for about 24 hours, and coagulating the weak gel solution to form gel;
3) preparing 0.5 mass percent of cocamidopropyl betaine solution, and injecting the solution into a water injection well through an injection pump, wherein the solution enters a petroleum reservoir through a perforation section of the water injection well;
4) and injecting water to the oil pipe of the water injection well through a water injection pump to extract oil.
In the embodiment, after crude oil recovery is carried out on the Hu 171 well group of the Changqing oil field in 12 months in 2018 and by the steps, the Hu 171 water injection well corresponds to 5 oil wells (namely production wells) by the expiration date, wherein the oil content of four oil wells is remarkably increased, the oil wells are cumulatively increased by 982.92t, and the water content of the 4 oil wells is cumulatively reduced by 1362.98m3At present, the oil well still continues to increase oil and the water content still continues to decrease.
Example 2:
in this embodiment, the 157 and 462 well group is installed in the huqin 154 area of the Changqing oil field in 12 months in 2018 as an example, and the crude oil recovery of the 157 and 462 well group includes the following steps:
1) preparing weak gel solution, wherein the mass fractions of 4 raw materials of the weak gel solution are 0.15 percent of polyacrylamide, 0.20 percent of chromium acetate, 0.015 percent of resorcinol and 0.03 percent of ammonium chloride; injecting the prepared weak gel solution into a petroleum layer of a corresponding perforation section through an oil pipe of the water injection well, wherein the weak gel solution enters a water-mixing channel in the petroleum reservoir;
2) after the injection of the weak gel solution is finished, closing the well for coagulation, waiting for about 24 hours, and coagulating the weak gel solution to form gel;
3) preparing 0.5 mass percent of cocamidopropyl betaine solution, and injecting the solution into a water injection well through an injection pump, wherein the solution enters a petroleum reservoir through a perforation section of the water injection well;
4) and injecting water to the oil pipe of the water injection well through a water injection pump to extract oil.
In the embodiment, after crude oil recovery is carried out on 310-09 well groups in Rou228 region of the Changqing oil field by the steps, the corresponding 6 oil wells of the water injection well with 157-462 are added in the Hu 154 region in the verified production period, wherein the oil content of 4 oil wells is remarkably increased, the oil wells are cumulatively increased by 341.58t, and the water content of the 4 oil wells is cumulatively reduced by 902.15m3It is still effective at present, i.e. the oil well is still increasing and the water content is still decreasing.
Example 3:
in the embodiment, the 167-cake 242 well group is installed in the huqin 154 area of the Changqing oil field construction in 11 months in 2018 as an example, and the crude oil recovery of the 157-cake 242 well group comprises the following steps:
1) preparing weak gel solution, wherein the mass fractions of 4 raw materials of the weak gel solution are 0.15 percent of polyacrylamide, 0.20 percent of chromium acetate, 0.015 percent of resorcinol and 0.03 percent of ammonium chloride; injecting the prepared weak gel solution into a petroleum layer of a corresponding perforation section through an oil pipe of the water injection well, wherein the weak gel solution enters a water-mixing channel in the petroleum reservoir;
2) after the injection of the weak gel solution is finished, closing the well for coagulation, waiting for about 24 hours, and coagulating the weak gel solution to form gel;
3) preparing 0.6 mass percent of cocamidopropyl betaine solution, and injecting the solution into a water injection well through an injection pump, wherein the solution enters a petroleum reservoir through a perforation section of the water injection well;
4) and injecting water to the oil pipe of the water injection well through a water injection pump to extract oil.
In the embodiment, after crude oil recovery is carried out by arranging 167-242 well groups in the Hu 154 area of the Changqing oil field through the steps, the crude oil recovery is stopped to 310-03 water injection wells in the Hu 154 area in the production period, corresponding to 6 oil wells, the oil content of four oil wells is remarkably increased, the oil content is increased by 331.91t in an accumulated way, and the water content of the 4 oil wells is reduced by 505.12m in an accumulated way3At present, the oil well still continues to increase oil and the water content still continues to decrease. .
Through the three embodiments, the method provided by the invention improves the recovery sweep efficiency of the crude oil, improves the oil displacement efficiency of the crude oil, and finally greatly improves the recovery ratio of the crude oil.
The maximum valid period days of the existing requirements are usually 400 days, and the test data of the three examples show that the valid period of the invention is far more than 400 days, the oil increasing effect is very outstanding, the oil displacement efficiency of crude oil is improved, and the recovery ratio of the crude oil is greatly improved.
The above list of details is only a detailed description of possible embodiments of the invention, and they are not intended to limit the scope of the invention, which is intended to include all equivalent embodiments or modifications without departing from the scope of the invention.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (6)
1. A method for improving the oil recovery rate by continuous phase complex oil displacement is characterized by comprising the following steps,
1) preparing weak gel solution, injecting the weak gel solution into the petroleum layer of the corresponding perforation section through the oil pipe of the water injection well, enabling the weak gel solution to enter a water-mixing channel in the petroleum reservoir,
the effective components of the weak gel solution comprise 4 raw materials of polyacrylamide, chromium acetate, resorcinol and ammonium chloride, and the mass fractions of the 4 raw materials are as follows:
0.12-0.22% of polyacrylamide, 0.18-0.3% of chromium acetate, 0.001-0.002% of resorcinol and 0.02-0.04% of ammonium chloride;
2) after the injection of the weak gel solution is finished, closing the well for waiting coagulation, and waiting for the weak gel solution to coagulate into gel;
3) the method comprises the steps of preparing the cocamidopropyl betaine solution with the mass fraction of 0.1-1.0%, injecting the solution into a water injection well through an injection pump, and enabling the solution to enter a petroleum reservoir through a perforation section of the water injection well.
2. The method of claim 1,
and 4) injecting water into the oil pipe of the water injection well through a water injection pump, wherein the volume of the injected water is slightly larger than that of the oil pipe of the water injection well.
3. The method according to claim 1 or 2,
in the step 1), the mass fractions of polyacrylamide, chromium acetate, resorcinol and ammonium chloride are 0.15%, 0.20%, 0.015% and 0.03%, respectively.
4. The method of claim 3,
the mass fraction of the cocamidopropyl betaine solution is 0.5-0.6%.
5. The weak gel solution for improving the reservoir oil recovery rate is characterized in that the effective components of the weak gel solution comprise 4 raw materials of polyacrylamide, chromium acetate, resorcinol and ammonium chloride, wherein the mass fractions of the 4 raw materials are as follows:
0.12-0.22% of polyacrylamide, 0.18-0.3% of chromium acetate, 0.001-0.002% of resorcinol and 0.02-0.04% of ammonium chloride.
6. The weak gelling solution of claim 5, wherein the mass fractions of polyacrylamide, chromium acetate, resorcinol and ammonium chloride are 0.15%, 0.20%, 0.015% and 0.03%, respectively.
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