Disclosure of Invention
The technical problem to be solved by the invention is to provide a selective water plugging method for a fractured low-permeability oil reservoir multi-section plug oil well, aiming at the defects of the prior art, the method comprises the steps of injecting a protective section plug, cleaning a blast hole and a near-well stratum through a surfactant solution, and then performing a pre-adsorption retention effect on a polymer solution, so as to protect the injection of a second-stage section plug, or directly injecting the polymer solution as the protective section plug; then injecting a second-stage slug to plug cracks, large pore passages and a high permeability layer in the stratum, forcing incoming water to change direction and effectively enlarging the swept volume of subsequently injected water; then injecting a selective plugging slug to perform oil-water selective plugging on the channel, after injecting the jelly selective phase permeation regulator into the production well, performing expansion ionization in the stratum, wherein the electronic electrostatic action and the macromolecule winding action of the jelly selective phase permeation regulator have good affinity with the stratum, meanwhile, a filter screen is formed in each production layer, the filter screen formed by a low-permeability oil layer under natural conditions is thin, the filter screen formed by a high-permeability water production layer or an oil-water layer is thick, and a grid structure formed by the jelly selective phase permeation regulator under the ground greatly reduces the water permeability because molecular chains stretch when encountering water; when oil is encountered, molecules shrink, intermolecular pores are enlarged, and oil smoothly passes through, so that the output liquid of a high-yield water layer is inhibited, and a low-permeability oil layer can still continue to produce, thereby achieving the aim of selectively plugging the stratum, really realizing effective water plugging of a fractured low-permeability oil reservoir oil well and prolonging the effective period of measures.
In order to solve the technical problems, the invention adopts the technical scheme that: a selective water plugging method for a multi-section plug oil well of a fractured low-permeability reservoir comprises the following steps: injecting a protective slug, a second-stage slug, a selective plugging slug and a sealing protective slug into an oil well of the fractured low-permeability oil reservoir in sequence for selective water plugging;
s1, injecting a protective slug:
injecting 10m in oil well of fractured low-permeability reservoir3～20m3Then 30m of surfactant solution was injected3Or by direct injection of 40m into the well of a fractured low permeability reservoir3～50m3The polymer solution of (a) as a protective slug;
s2, second-stage slug injection:
when the oil well of the fractured low-permeability oil reservoir is an oil well with stratum fracture development, injecting 80m of the oil well into the oil well in sequence3～100m3Plugging pills a and 100m3～150m3The plugging slug b is used as a second-stage slug;
low permeability reservoir when fracturedWhen the oil well is an oil well with a non-developed stratum crack and an artificial fracturing crack, 100m of the oil well is injected3～150m3The plugging slug b is used as a second-stage slug;
the strength of the plugging slug a is 30000mPa & s-50000 mPa & s; the strength of the plugging slug b is 3000mPa & s-10000 mPa & s;
s3, injecting a selective plugging slug:
injection of 200m into a well of a fractured low permeability reservoir3～600m3The jelly selective phase permeation regulator is used as a selective plugging slug;
s4, sealing and protecting the slug:
injecting 50m into oil well of fractured low-permeability reservoir3～100m3The interface modifier is used as a sealing protective slug.
Preferably, the surfactant solution in S1 is a fatty alcohol-polyoxyethylene ether sulfonate aqueous solution with a mass fraction of 0.3% to 0.5% or a fatty alcohol-polyoxyethylene ether carboxylate aqueous solution with a mass fraction of 0.3% to 0.5%; the polymer solution is a starch graft polymer aqueous solution with the mass fraction of 0.8-1.0% or an anionic polyacrylamide aqueous solution with the mass fraction of 0.8-1.0%.
Preferably, the plugging slug a in S2 is a jelly or an inorganic gel plugging agent.
Preferably, the jelly is 0.8% of starch graft polymer aqueous solution by mass fraction; the inorganic gel plugging agent is a silicate aqueous solution with the mass fraction of 0.8%, and the mass fraction of silicate in the inorganic gel plugging agent is 0.8%.
Preferably, the blocking slug b in S2 is a gel system.
Preferably, the gel system is a pre-crosslinking particle aqueous solution with the mass fraction of 0.2-0.5% or an aqueous solution of a mixture of anionic polyacrylamide and a phenolic resin crosslinking agent with the mass fraction of 0.2-0.5%, and the mass ratio of the anionic polyacrylamide and the phenolic resin crosslinking agent in the aqueous solution of the mixture of anionic polyacrylamide and the phenolic resin crosslinking agent is 1: 1.
preferably, the jelly selective phase permeation regulator in S3 is a water-soluble polysaccharide swelling resin aqueous solution with the mass fraction of 0.5%.
Preferably, the interface modifier in S4 is an anionic and cationic complex surfactant solution.
Compared with the prior art, the invention has the following advantages:
the invention relates to a method for selectively plugging a large pore passage high permeability layer of a crack, can realize less water production and more oil production of an oil well and avoid the risk of stratum blockage failure or blockage by adopting a multi-section plugging oil well selective water plugging method, wherein a protective section plug is firstly injected, a blast hole and a near-well stratum are firstly cleaned by a surfactant solution and then a polymer solution plays a role in pre-adsorption retention, and a protective effect is played on the injection of a second section plug, or a polymer solution is directly injected to serve as the protective section plug. Then injecting a second-stage slug, when the oil well of the fractured low-permeability oil reservoir is an oil well with stratum fracture development, injecting a high-strength plugging slug a into the second-stage slug, wherein the plugging slug a cannot enter a high-permeability layer and a matrix, mainly travels along the fracture to plug the fracture and a super-large pore passage in the stratum, and then injecting a low-strength plugging slug b into the second-stage slug to realize effective plugging of the large pore passage and the high-permeability layer, plugging the fracture, the large pore passage and the high-permeability layer in the stratum through the second-stage slug (the plugging slug a and the plugging slug b), forcing incoming water to be redirected, and effectively expanding the swept volume of subsequent injected water; when the oil well of the fractured low-permeability reservoir is a stratum fracture which does not develop, the plugging slug b with low injection strength is used as a second-stage slug, and the effective plugging of a large pore passage and a high permeability layer can be realized. Injecting a selective plugging slug on the basis of effectively plugging cracks, large pore channels and a high permeability layer in a stratum, injecting a jelly selective phase permeation regulator into a production well, performing expansion ionization in the stratum, performing electron electrostatic action and macromolecule winding action on the jelly selective phase permeation regulator, and ensuring good affinity with the stratum, forming a filter screen in each production layer, forming a thin filter screen in a low permeability oil layer under natural conditions, forming a thick filter screen in a high permeability water layer or an oil water layer, and forming a grid structure in the ground by the jelly selective phase permeation regulator, wherein when encountering water, molecular chains stretch, and the water permeability is greatly reduced; when oil is encountered, molecules shrink, intermolecular pores are enlarged, oil smoothly passes through, the output liquid of a high-yield water layer is inhibited, a low-permeability oil layer can still continue to produce, the selective plugging slug has strong oil-water selective plugging capability, only water plugging and oil plugging are realized, a water flow channel can be effectively plugged, the smoothness of the oil flow channel is ensured, injection liquid and formation water can be plugged in a formation without production, the oil well is prevented from being drowned by the injection liquid, the oil well produces more oil, and water or water is produced as little as possible, so that the aim of selectively plugging the formation is fulfilled, the effective water plugging of the oil well with the low-permeability fractured reservoir is really realized, and the effective period of measures is prolonged. And finally, injecting an interface modifier as a seal protection slug, on one hand, pushing the slugs into the deep part of an oil layer to prevent the oil well from being pumped to a shaft to block an oil well pump during pumping, and on the other hand, removing the residues of the slugs to strengthen the seepage capability of the near-wellbore area of the oil well so that the oil in the stratum can be smoothly produced.
The present invention will be described in further detail with reference to examples.
Detailed Description
Example 1
The oil well of the embodiment belongs to a low-permeability oil well with stratum microcrack development, the well depth is 2109m, the oil layer temperature is 57 ℃, the stratum water mineralization is 89120mg/L, and Ca is added2+、Mg2+The ion concentration was 664.7 mg/L. The well is produced in 6 layers of 6 months, and is immediately flooded with water after production, and the average daily water yield is 14.62m3And contains 100 percent of water. Closing the well in the next 5 months, installing a high-pressure wellhead, stopping the well, observing, stopping the injection of the corresponding 2 water injection wells, analyzing and considering that a fractured series connection exists between the oil well and the corresponding water well, wherein the well has a fracture, selectively plugging the well in 2011 in 6 months, and adopting a fractured low-permeability oil reservoir multi-section plugging oil well selective plugging method.
The method for selectively blocking water of the fractured low-permeability reservoir multi-section plug oil well comprises the following steps: injecting a protective slug, a second-stage slug, a selective plugging slug and a sealing protective slug into an oil well of the fractured low-permeability oil reservoir in sequence for selective water plugging;
s1, injecting a protective slug:
direct injection of 40m into a well of a fractured low permeability reservoir3The polymer solution of (a) as a protective slug; the polymer solution plays a role in pre-adsorption and retention and plays a role in protecting the injection of the second-stage slug; the polymer solution is a starch graft polymer aqueous solution with the mass fraction of 0.8%;
s2, second-stage slug injection:
because the oil well of the fractured low-permeability oil reservoir is an oil well with stratum fracture development, the plugging slug a and the plugging slug b are injected in sequence to be used as a second-stage slug;
the strength of the plugging slug a is 50000mPa & s; the strength of the plugging slug b is 10000mPa & s;
the injection method of the plugging slug a comprises the following steps: injection of 80m into the well of a fractured low permeability reservoir3The jelly of (2); the jelly is a starch graft polymer aqueous solution with the mass fraction of 0.8%;
the injection method of the plugging slug b comprises the following steps: injection of 100m into a well of a fractured low permeability reservoir3The gel system of (a); the gel system with the mass fraction of 0.2 percent is a pre-crosslinked particle aqueous solution;
the purpose of the second-stage slug injection is to plug cracks, large channels and high depth layers in the stratum, force the incoming water to change direction and effectively enlarge the swept volume of the subsequently injected water;
s3, injecting a selective plugging slug:
injection of 200m into a well of a fractured low permeability reservoir3The jelly selective phase permeation regulator is used as a selective plugging slug; after the gel selective phase permeation regulator is injected into a production well, the gel selective phase permeation regulator is expanded and ionized in a stratum, the electron electrostatic effect and the macromolecule winding effect of the gel selective phase permeation regulator have good affinity with the stratum, and meanwhile, a filter screen is formed in each production layer; under natural conditions, the filter screen formed by the low-permeability oil layer is thin, and the filter screen formed by the high-permeability water production layer or the oil-water layer is thick; selective phase permeation regulator for jellyWhen the grid structure formed underground encounters water, molecular chains stretch, so that the water permeability is greatly reduced; when encountering oil, molecules shrink, intermolecular pores are enlarged, and the oil smoothly passes through, so that the output liquid of a high-yield water layer is inhibited, and a low-permeability oil layer can still continue to produce, thereby achieving the aim of selectively plugging the stratum;
the gel selective phase permeation regulator is a glycan water-soluble expanded resin aqueous solution, and the mass fraction of glycan water-soluble expanded resin in the gel selective phase permeation regulator is 0.5%;
s4, sealing and protecting the slug:
injecting 50m into oil well of fractured low-permeability reservoir3The interface modifier is used as a sealing protective slug; the interface modifier is a composite anionic and cationic surfactant solution; the seal protection slug can effectively protect the selective plugging slug, and can improve the seepage capability of the low-permeability pore canal and ensure the smoothness of the produced oil flow channel.
After the oil well is plugged by the selective water plugging method of the fractured low-permeability reservoir multi-section plugging oil well of the embodiment, the daily oil production is increased to 3.8 tons, the water content is reduced to 60 percent, the effective period reaches 19 months, and 512 tons of oil are accumulated.
Example 2
The stratum fractures of the oil well of the embodiment do not develop, but the well fracturing operation has artificial fracturing fractures and large channels, the production well section of the oil well is 2167.5-2304.9 m, the thickness of an oil layer is 13 layers and 23.3m, the production layer position is 4-7 below sand, and the stratum permeability is 49 multiplied by 10-3μm2The well temperature is 85 ℃, and the degree of mineralization is 29 multiplied by 104mg/L, the extraction degree is 36.1 percent. The well layer has long multi-well sections and multi-layer water outlet, the upper part and the lower part of the position 2051.5m are sleeved, the minimum diameter is reduced to 91mm, a tool cannot be put into the well for plugging, and the well is subjected to multi-section plugging oil well selective water plugging, wherein the multi-section plugging oil well selective water plugging adopts a fracture low-permeability oil reservoir multi-section plugging oil well selective water plugging method.
The method for selectively blocking water of the fractured low-permeability reservoir multi-section plug oil well comprises the following steps: injecting a protective slug, a second-stage slug, a selective plugging slug and a sealing protective slug into an oil well of the fractured low-permeability oil reservoir in sequence for selective water plugging;
s1, injecting a protective slug:
direct injection of 50m into a well of a fractured low permeability reservoir3The polymer solution of (a) as a protective slug; the surfactant solution can clean the blast hole and the near-well stratum, and the polymer solution plays a role in pre-adsorption retention and plays a role in protecting the injection of the second-stage slug; the polymer solution is a starch graft polymer aqueous solution with the mass fraction of 1.0%;
s2, second-stage slug injection:
because the oil well of the fractured low-permeability oil reservoir of the embodiment is an oil well in which stratum fractures do not develop and fractures are artificially fractured, the plugging slug b is injected to serve as a second-stage slug; the strength of the plugging slug b is 3000mPa & s;
the injection method of the plugging slug b comprises the following steps: injecting 120m into oil well of fractured low-permeability reservoir3The gel system of (a); the gel system is an aqueous solution of a mixture of anionic polyacrylamide and a phenolic resin cross-linking agent with the mass fraction of 0.5%, and the mass ratio of the anionic polyacrylamide to the phenolic resin cross-linking agent in the aqueous solution of the mixture of anionic polyacrylamide and the phenolic resin cross-linking agent is 1: 1;
the purpose of the second-stage slug injection is to plug cracks, large channels and high depth layers in the stratum, force the incoming water to change direction and subsequently inject the swept volume of the water;
s3, injecting a selective plugging slug:
600m injection in wells of fractured low permeability reservoirs3The jelly selective phase permeation regulator is used as a selective plugging slug; after the gel selective phase permeation regulator is injected into a production well, the gel selective phase permeation regulator is expanded and ionized in a stratum, the electron electrostatic effect and the macromolecule winding effect of the gel selective phase permeation regulator have good affinity with the stratum, and meanwhile, a filter screen is formed in each production layer; formation of hypotonic oil layer under natural conditionsThe filter screen is thin, and the filter screen formed by the high-permeability water production layer or the oil-water layer is thick; the gel selective phase permeation regulator forms a grid structure under the ground, and molecular chains stretch when encountering water, so that the water permeability is greatly reduced; when encountering oil, molecules shrink, intermolecular pores are enlarged, and the oil smoothly passes through, so that the output liquid of a high-yield water layer is inhibited, and a low-permeability oil layer can still continue to produce, thereby achieving the aim of selectively plugging the stratum;
the gel selective phase permeation regulator is a glycan water-soluble expanded resin aqueous solution, and the mass fraction of glycan water-soluble expanded resin in the gel selective phase permeation regulator is 0.5%;
s4, sealing and protecting the slug:
injection of 100m into a well of a fractured low permeability reservoir3The interface modifier is used as a sealing protective slug; the interface modifier is a composite anionic and cationic surfactant solution; the seal protection slug can effectively protect the selective plugging slug, and can improve the seepage capability of the low-permeability pore canal and ensure the smoothness of the produced oil flow channel.
After the oil well is plugged by the selective water plugging method of the fractured low-permeability reservoir multi-section plugging oil well of the embodiment, the daily oil yield is averagely increased from 0.6 ton to 1.5 ton, the maximum daily yield is 3.3 ton, the cumulative oil increase reaches 874 ton, and the effective period is 2 years.
Example 3
The stratum fractures of the oil well of the embodiment do not develop, but the fracturing operation of the well has artificial fracturing fractures and large channels, the production well section of the oil well is 2367.5-2404.9 m, the thickness of an oil layer is 15 layers and 28.5m, the production layer position is 5-8 below sand, and the stratum permeability is 45 multiplied by 10-3μm2The well temperature is 87 ℃ and the degree of mineralization is 30.5 multiplied by 104mg/L, the extraction degree is 32.1 percent. The well layer is drained in multiple layers, selective water plugging of the oil well is carried out on the well in multiple sections, and the selective water plugging of the oil well in multiple sections adopts a selective water plugging method of a fractured low-permeability oil reservoir in multiple sections.
The method for selectively blocking water of the fractured low-permeability reservoir multi-section plug oil well comprises the following steps: injecting a protective slug, a second-stage slug, a selective plugging slug and a sealing protective slug into an oil well of the fractured low-permeability oil reservoir in sequence for selective water plugging;
s1, injecting a protective slug:
injecting 10m in oil well of fractured low-permeability reservoir3Then 30m of surfactant solution was injected3Or directly injecting 50m in the oil well of a fractured low-permeability reservoir3The polymer solution of (a) as a protective slug; the surfactant solution can clean the blast hole and the near-well stratum, and the polymer solution plays a role in pre-adsorption retention and plays a role in protecting the injection of the second-stage slug; the surfactant solution is 0.3% of fatty alcohol-polyoxyethylene ether sulfonate aqueous solution, and the polymer solution is 0.8% of anionic polyacrylamide aqueous solution in mass fraction;
s2, second-stage slug injection:
because the oil well of the fractured low-permeability oil reservoir is an oil well with stratum fracture development, the plugging slug a and the plugging slug b are injected in sequence to be used as a second-stage slug;
the strength of the plugging slug a is 30000mPa & s; the strength of the plugging slug b is 3000mPa & s;
the injection method of the plugging slug a comprises the following steps: injection of 100m into a well of a fractured low permeability reservoir3The inorganic gel blocking agent of (1); the inorganic gel plugging agent is a silicate aqueous solution with the mass fraction of 0.8%;
the injection method of the plugging slug b comprises the following steps: 150m injection into wells of fractured low permeability reservoirs3The gel system of (a); the gel system is an aqueous solution of a mixture of anionic polyacrylamide and a phenolic resin cross-linking agent with the mass fraction of 0.2%, and the mass ratio of the anionic polyacrylamide to the phenolic resin cross-linking agent in the aqueous solution of the mixture of anionic polyacrylamide and the phenolic resin cross-linking agent is 1: 1;
the purpose of the second-stage slug injection is to plug cracks, large channels and high depth layers in the stratum, force the incoming water to change direction and effectively enlarge the swept volume of the subsequently injected water;
s3, injecting a selective plugging slug:
injection of 400m into a well of a fractured low permeability reservoir3The jelly selective phase permeation regulator is used as a selective plugging slug; after the gel selective phase permeation regulator is injected into a production well, the gel selective phase permeation regulator is expanded and ionized in a stratum, the electron electrostatic effect and the macromolecule winding effect of the gel selective phase permeation regulator have good affinity with the stratum, and meanwhile, a filter screen is formed in each production layer; under natural conditions, the filter screen formed by the low-permeability oil layer is thin, and the filter screen formed by the high-permeability water production layer or the oil-water layer is thick; the gel selective phase permeation regulator forms a grid structure under the ground, and molecular chains stretch when encountering water, so that the water permeability is greatly reduced; when encountering oil, molecules shrink, intermolecular pores are enlarged, and the oil smoothly passes through, so that the output liquid of a high-yield water layer is inhibited, and a low-permeability oil layer can still continue to produce, thereby achieving the aim of selectively plugging the stratum;
the gel selective phase permeation regulator is a glycan water-soluble expanded resin aqueous solution, and the mass fraction of glycan water-soluble expanded resin in the gel selective phase permeation regulator is 0.5%;
s4, sealing and protecting the slug:
injection of 80m into the well of a fractured low permeability reservoir3The interface modifier is used as a sealing protective slug; the interface modifier is a composite anionic and cationic surfactant solution; the seal protection slug can effectively protect the selective plugging slug, and can improve the seepage capability of the low-permeability pore canal and ensure the smoothness of the produced oil flow channel.
After the oil well is plugged by the selective water plugging method of the fractured low-permeability reservoir multi-section plugging oil well of the embodiment, the daily oil yield is averagely increased from 0.9 ton to 2.2 tons, the maximum daily yield is 3.1 tons, the accumulated oil increase reaches 567 tons, and the effective period is 15 months.
In the embodiment, a selective water plugging method of a multi-section plug oil well is adopted, a protective section plug is injected firstly, a surfactant solution is used for cleaning a blast hole and a near-well stratum firstly, then a polymer solution plays a role in pre-adsorption retention, and a secondary section plug is injected for protection; then injecting a second-stage slug to plug cracks, large pore passages and a high permeability layer in the stratum, forcing incoming water to change direction and effectively enlarging the swept volume of subsequently injected water; then injecting a selective plugging slug to perform oil-water selective plugging on the channel, after injecting the jelly selective phase permeation regulator into the production well, performing expansion ionization in the stratum, wherein the electronic electrostatic action and the macromolecule winding action of the jelly selective phase permeation regulator have good affinity with the stratum, meanwhile, a filter screen is formed in each production layer, the filter screen formed by a low-permeability oil layer under natural conditions is thin, the filter screen formed by a high-permeability water production layer or an oil-water layer is thick, and a grid structure formed by the jelly selective phase permeation regulator under the ground greatly reduces the water permeability because molecular chains stretch when encountering water; when oil is encountered, molecules shrink, intermolecular pores are enlarged, and oil smoothly passes through, so that the output liquid of a high-yield water layer is inhibited, and a low-permeability oil layer can still continue to produce, thereby achieving the aim of selectively plugging the stratum, really realizing effective water plugging of a fractured low-permeability oil reservoir oil well and prolonging the effective period of measures.
Example 4
The stratum fractures of the oil well of the embodiment do not develop, but the well fracturing operation has artificial fracturing fractures and large channels, the production well section of the oil well is 3107.5-3203.5 m, the thickness of an oil layer is 21 layers and 43.3m, the production layer position is 2-3 below Sansha, and the stratum permeability is 15 multiplied by 10-3μm2The well temperature is 105 ℃, and the degree of mineralization is 35 multiplied by 104mg/L, the extraction degree is 30.1 percent. The well layer has long multi-well section, water is discharged from multiple layers, and selective water plugging of the oil well is carried out on the well by adopting a selective water plugging method of a fractured low-permeability oil reservoir multi-section plugging oil well.
The method for selectively blocking water of the fractured low-permeability reservoir multi-section plug oil well comprises the following steps: injecting a protective slug, a second-stage slug, a selective plugging slug and a sealing protective slug into an oil well of the fractured low-permeability oil reservoir in sequence for selective water plugging;
s1, injecting a protective slug:
in crack formationInjecting 20m in oil well of low-permeability oil reservoir3Then 30m of surfactant solution was injected3Or by direct injection of 40m into the well of a fractured low permeability reservoir3The polymer solution of (a) as a protective slug; the surfactant solution can clean the blast hole and the near-well stratum, and the polymer solution plays a role in pre-adsorption retention and plays a role in protecting the injection of the second-stage slug; the surfactant solution is a fatty alcohol-polyoxyethylene ether carboxylate aqueous solution with the mass fraction of 0.5%, the fatty alcohol-polyoxyethylene ether carboxylate in the surfactant solution, and the polymer solution is an anionic polyacrylamide aqueous solution with the mass fraction of 1.0%;
s2, second-stage slug injection:
because the oil well of the fractured low-permeability oil reservoir of the embodiment is an oil well in which stratum fractures do not develop and fractures are artificially fractured, the plugging slug b is injected to serve as a second-stage slug;
the strength of the plugging slug b is 10000mPa & s;
the injection method of the plugging slug b comprises the following steps: injection of 100m into a well of a fractured low permeability reservoir3The gel system of (a); the gel system is a pre-crosslinked particle aqueous solution with the mass fraction of 0.5%;
the purpose of the second-stage slug injection is to plug cracks, large channels and high depth layers in the stratum, force the incoming water to change direction and effectively enlarge the swept volume of the subsequently injected water;
s3, injecting a selective plugging slug:
600m injection in wells of fractured low permeability reservoirs3The jelly selective phase permeation regulator is used as a selective plugging slug; after the gel selective phase permeation regulator is injected into a production well, the gel selective phase permeation regulator is expanded and ionized in a stratum, the electron electrostatic effect and the macromolecule winding effect of the gel selective phase permeation regulator have good affinity with the stratum, and meanwhile, a filter screen is formed in each production layer; under natural conditions, the filter screen formed by the low-permeability oil layer is thin, and the filter screen formed by the high-permeability water production layer or the oil-water layer is thick; the grid structure formed by the jelly selective phase permeation regulator in the ground can greatly reduce molecular chain extension when encountering waterLow water permeability; when encountering oil, molecules shrink, intermolecular pores are enlarged, and the oil smoothly passes through, so that the output liquid of a high-yield water layer is inhibited, and a low-permeability oil layer can still continue to produce, thereby achieving the aim of selectively plugging the stratum;
the gel selective phase permeation regulator is a glycan water-soluble expanded resin aqueous solution, and the mass fraction of glycan water-soluble expanded resin in the gel selective phase permeation regulator is 0.5%;
s4, sealing and protecting the slug:
injecting 50m into oil well of fractured low-permeability reservoir3The interface modifier is used as a sealing protective slug; the interface modifier is a composite anionic and cationic surfactant solution; the seal protection slug can effectively protect the selective plugging slug, and can improve the seepage capability of the low-permeability pore canal and ensure the smoothness of the produced oil flow channel.
After the oil well is plugged by the selective water plugging method of the fractured low-permeability reservoir multi-stage plugging oil well of the embodiment, the daily oil yield is averagely increased from 1.6 tons to 3.2 tons, the maximum daily yield is 4.1 tons, the accumulated oil increase reaches 941 tons, and the effective period is 18 months.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modification, change and equivalent changes of the above embodiments according to the technical essence of the invention are still within the protection scope of the technical solution of the invention.