CN111087997A - Method for blocking water in oil reservoir and oil well - Google Patents
Method for blocking water in oil reservoir and oil well Download PDFInfo
- Publication number
- CN111087997A CN111087997A CN201811242608.XA CN201811242608A CN111087997A CN 111087997 A CN111087997 A CN 111087997A CN 201811242608 A CN201811242608 A CN 201811242608A CN 111087997 A CN111087997 A CN 111087997A
- Authority
- CN
- China
- Prior art keywords
- water
- mixture
- mass
- plugging agent
- oil
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- 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
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
- C09K8/504—Compositions based on water or polar solvents
- C09K8/506—Compositions based on water or polar solvents containing organic compounds
- C09K8/508—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
- C09K8/512—Compositions based on water or polar solvents containing organic compounds macromolecular compounds containing cross-linking agents
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F251/00—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F251/00—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
- C08F251/02—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof on to cellulose or derivatives thereof
-
- 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
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
- C09K8/504—Compositions based on water or polar solvents
- C09K8/506—Compositions based on water or polar solvents containing organic compounds
- C09K8/508—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
- C09K8/5083—Compositions based on water or polar solvents containing organic compounds macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
-
- 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
- C09K8/887—Compositions based on water or polar solvents containing organic compounds macromolecular compounds containing cross-linking agents
-
- 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
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices, or the like
Abstract
The application provides a method for blocking water of an oil reservoir and an oil well, which comprises the following steps: 1) injecting a first plugging agent into the oil well at the front section plug, wherein the first plugging agent is a first mixture comprising expansion-slowing particles and water; 2) injecting a second plugging agent into the oil well at the main body slug, wherein the second plugging agent is a second mixture comprising polyacrylamide, polyethyleneimine and water; 3) and injecting a third plugging agent into the oil well at the sealing slug, wherein the third plugging agent is a third mixture comprising sodium soil, cement, a retarder and water.
Description
Technical Field
The application provides a method for water shutoff of an oil reservoir and an oil well.
Background
The proven reserves of the carbonate hydrocarbon reservoir account for more than 50% of the total amount of oil and gas resources, wherein more than 30% of the carbonate hydrocarbon reservoir is a fracture-cavity type hydrocarbon reservoir, and the development potential is huge. The Tahe oil field Ordovician reservoir is a typical representative of carbonate rock oil and gas reservoirs discovered in China, and has become the second largest oil and gas production area of medium petrochemicals except for the victory oil field due to large reserves.
The reservoir body of the oil reservoir is influenced by a plurality of functions such as tectonic movement, karst superposition transformation, multi-phase reservoir formation and the like, the reservoir body is generally a composite medium and comprises karst caves, cracks and dissolved pores, discontinuity exists in spatial distribution, a matrix does not have the capacity of storing and permeating, the heterogeneity of the reservoir layer is strong, and the relation of oil and water is complex. Leading to difficulties in the development of such reservoirs. Particularly in recent years, with the pressure attenuation and the water content increase in the middle and later stages of development, the water invasion of the bottom water of some oil wells is serious year by year, and the number of high-water-content oil wells increases year by year and reaches about 320; the water injection and water flooding efficiency shows a trend of deterioration, the water injection effect of a well group is deteriorated, the failure proportion is increased, the water flooding response degree is only 33.6 percent, the unidirectional effect and water channeling become main development contradictions, and the tower and river recovery ratio is only 14.8 percent and is far lower than the average level at home and abroad.
The large-area water outlet of the oil field causes the overall effect of oil field development to be poor, and great economic loss is caused, so that oil-stabilizing and water-controlling measures must be carried out to reduce the water content. On the premise of meeting the production requirements of oil fields, the water plugging technology is the best measure for reducing water outlet.
However, the water plugging of the carbonate fracture-cave type reservoir in the tower river oil field faces a plurality of technical difficulties, such as strong reservoir heterogeneity, complex underground oil-water relationship, difficult determination of water outlet layer sections and the like, so that the adaptability of the conventional water plugging process is poor; the effective application of the conventional high-strength or selective plugging agent is severely restricted by the characteristics of strong flow conductivity of a flow channel of a fracture-cavity reservoir, low stratum pressure gradient, easiness in leakage after production and vacancy, ultra-deep reservoir, high-temperature and high-salinity (the burial depth is 5400-6600 m, the temperature is 120-140 ℃, and the mineralization degree is 210-240 g/L) and the like.
Patent CN 102618232B (plugging agent for fracture-cavity type oil reservoir) reports a method for plugging water in fracture-cavity type oil reservoir, and is especially suitable for high salinity fracture-cavity type oil reservoir. The method comprises the steps of preparing a mixed solution from cement, micro-silicon, sodium bentonite, a polymer dispersant, a retarder and a sodium carbonate aqueous solution, injecting the mixed solution into an oil well, closing the well for a period of time, and then opening the well for production. Due to the fact that the density difference of the plugging agent and oil and water is utilized, the plugging agent can effectively reside between oil and water interfaces in the water plugging process of the fracture-cavity oil reservoir to plug a water outlet channel, oil and water in the water plugging agent are high in selectivity and strength, high-strength selective water plugging is achieved, and the on-site water control and oil increasing effects are obvious.
The patent CN 102587858B (method for water plugging of fracture-cavity reservoir) reports the use of CN 102618232B (plugging agent for fracture-cavity reservoir).
Patent CN 102746835B (carbonate oil well density selective water shutoff agent and preparation process thereof) reports a carbonate oil well density selective water shutoff agent and preparation process thereof. The invention prepares cement, fly ash, clay, micro-silicon, early strength agent and fluid loss agent into aqueous solution according to a certain proportion. By utilizing the density selectivity of the water plugging agent, the water plugging partition plate is easy to stay between oil-water interfaces, and plays a role in precipitation and oil increase.
According to the technical scheme, an oil-water interface low-density selective plugging agent system is developed indoors by optimizing different component ratios of superfine cement, a permeation enhancer, a framework bridging agent, a density regulator, a suspension dispersant, a water reducer, a retarder and the like in the document (evaluation of the performance of the Wexue oil-water interface low-density selective plugging agent [ J ]. development of fine petrochemical industry, 2015,16(4): 21-24).
The literature (Wu civilization, Tahe oilfield carbonate fracture-vug type reservoir water plugging technology [ J ] oil gas geology and recovery ratio, 2013,20(6): 104-.
In summary, the water plugging method for the fracture-cavity carbonate reservoir reported in the prior art is only suitable for reservoirs with obvious oil-water interfaces, and the related plugging agent and construction method can utilize the characteristic of density difference of fluid under the reservoir condition to play a role in water plugging; however, for water outflow of a fractured reservoir in a fractured-vuggy reservoir, fractures are not only seepage channels but also reservoir spaces, and reservoir fluids have no obvious oil-water interface, so that the existing method is difficult to meet the field requirements.
Research shows that in fractured reservoirs, the water output of oil wells is mainly influenced by the communication condition of fractures in the reservoirs and the size of the fracture. The better the crack communication condition is, the higher the crack flow conductivity is, after the oil well is exposed to water, the shielding effect of the large-scale crack on other cracks is stronger, and the water is easier to be extracted from a channel communicating the large-scale crack, which shows that the oil well has high water content. However, a large amount of residual oil in the reservoir is not used, and the oil reservoir has low oil utilization degree.
Therefore, the water plugging method for the fracture-cave type carbonate rock oil well has strong applicability and good effect, can meet the development requirement of a fractured oil reservoir, and can effectively plug the large fracture of the high-water-cut oil well after being applied to the site, so that oil flow flows out from other unused storage and seepage spaces, and the purposes of oil stabilization and water control are achieved.
Disclosure of Invention
The application provides a method for blocking water of an oil reservoir and an oil well, which comprises the following steps:
1) injecting a first plugging agent into the oil well at the front section plug, wherein the first plugging agent is a first mixture comprising expansion-slowing particles and water; the preparation method of the slow swelling particles comprises the following steps:
1-1) obtaining reaction raw materials, wherein the reaction raw materials comprise a graftable copolymer, acrylic acid, acrylamide, a cross-linking agent, an initiator and water;
1-2) dissolving the acrylic acid and acrylamide in water, adding the graft copolymer, fully dissolving, and introducing N2Then adding the initiator and the cross-linking agent, mixing uniformly, and continuously introducing N during mixing2Obtaining a mixture system;
1-3) reacting the mixed system under the heating condition to obtain a slow swelling gel block;
1-4) drying, crushing and sieving the slow swelling gel block to obtain slow swelling particles;
2) injecting a second plugging agent into the well at the body slug, the second plugging agent being a second mixture comprising polyacrylamide and an organic cross-linking agent (e.g., polyethyleneimine) with water; wherein the polyacrylamide has a degree of hydrolysis of 15% to 30% and a molecular weight of 500 to 2000 ten thousand;
3) and injecting a third plugging agent into the oil well at the sealing slug, wherein the third plugging agent is a third mixture comprising sodium soil, cement, a retarder and water.
In a specific embodiment, the content of the slow swelling particles in the first mixture is 0.2% to 2% by mass.
In a specific embodiment, the content of the polyacrylamide in the second mixture is 0.5% to 1.5% by mass; the polyethyleneimine is present in the second mixture in an amount of 0.15% to 0.35%.
In a specific embodiment, the content of the sodium soil in the third mixture is 5 to 10% by mass; the content of the cement in the third mixture is 20% to 40%; the retarder is present in the third mixture in an amount of 0.01% to 1%.
In a particular embodiment, the total amount of said first, second and third plugging agent does not exceed 500m3。
In a specific embodiment, the concentration of the water solution of the slow swelling particle of the front slug is not particularly limited, and preferably, the amount of the first plugging agent is 10 to 25 percent of the total amount by volume percentage.
In a specific embodiment, the concentration of the system in the bulk slug is not particularly limited, and preferably, the second plugging agent is used in an amount of 60 to 75 volume percent of the total amount.
In a specific embodiment, the concentration of the system for sealing the slug is not particularly limited, and preferably, the third plugging agent is used in an amount of 10 to 15% by volume of the total amount.
In one embodiment, in step 1), step 2) and step 3), the injection speed of the plugging agent is 3-15m independently3/h。
In a specific embodimentIn an embodiment, the injection rate of the blocking agent in step 1), step 2) and step 3) is preferably 9 to 10m, independently of each other3H is used as the reference value. However, the injection speed in the actual use process needs to be determined according to the field situation, and can be controlled to be any value within a certain range.
In a specific embodiment, the cement is a grade G cement.
In one embodiment, the set retarder is a borate and/or silicate. Such as sodium borate.
In one embodiment, in the process of preparing the slow swelling particle, the graftable copolymer accounts for 10% to 55%, the acrylamide accounts for 5% to 10%, the acrylic acid accounts for 3% to 5%, the crosslinking agent accounts for 0.03% to 0.5%, the initiator accounts for 0.02% to 0.15%, and the water accounts for 29.35% to 81.95%, based on 100% of the total mass of the mixture system.
In a specific embodiment, in the process of preparing the slow swelling particles, in the step 1-2), N is introduced for the first time2For 10 to 30 minutes, and introducing N for the second time2For a period of 5 to 15 minutes.
In a specific embodiment, in the process of preparing the slow swelling particles, in the step 1-3), the reaction is carried out for 4 to 6 hours by heating to 50 to 55 ℃.
In a particular embodiment, during the preparation of the slow-swelling granules, the graftable copolymer is selected from at least one of chitin, chitosan, soluble starch, carboxymethyl cellulose, guar gum and fenugreek gum.
In one embodiment, in the process of preparing the slow swelling particles, the crosslinking agent is an organic titanium crosslinking agent.
In one embodiment, the organotitanium crosslinking agent is prepared as follows: mixing triethanolamine and ethanol, adding tetraisopropyl titanate under the condition of stirring, heating and continuously stirring for reaction, thereby obtaining the organic titanium crosslinking agent.
In one embodiment, in the process of preparing the organic titanium crosslinking agent, the mass ratio of the triethanolamine, the ethanol and the tetraisopropyl titanate is (1-2): 0.8: (0.8-0.4).
In one embodiment, during the preparation of the organotitanium crosslinking agent, the temperature is raised to 45 to 65 ℃ for reaction for 3 to 6 hours.
In a specific embodiment, in the preparing of the organic titanium crosslinking agent, the initiator is at least one of ammonium persulfate, potassium persulfate, sodium sulfite, and sodium bisulfite.
In a specific embodiment, in the process of preparing the slow swelling granules, in the step 1-3), the drying temperature is 80-95 ℃, and the drying time is 5-12 hours; the granularity after crushing and sieving is 100 to 120 meshes.
"graftable copolymer" as used herein refers to a copolymer that has not undergone a grafting reaction, wherein the backbone units of the "copolymer" are capable of incorporating other monomer units to form new branches.
The beneficial effect of this application:
(1) the slow-swelling particles can be prepared into particles with proper particle size according to the field requirement, so the particle size is adjustable, the suspension property in the solution is good, and the preparation and the field pumping injection are facilitated;
(2) the slow expansion particles slowly absorb water and expand, so that the slow expansion particles can be injected into deep parts in the stratum, and after the slow expansion particles completely absorb water, gel particles with high strength and certain toughness are formed;
(3) the slow expansion particles can be used under the conditions of high temperature, high calcium and magnesium and high mineralization degree, can effectively block cracks, block water outlet channels and finally achieve the purposes of oil increasing and water controlling.
(4) The method for blocking water in the oil reservoir oil well has wide application range of stratum conditions, and the temperature of the stratum needing water blocking is preferably less than or equal to 150 ℃, and more preferably 90-140 ℃; the degree of mineralization of the groundwater is preferably less than or equal to 250,000 mg/L. The method can realize effective plugging of the fractured carbonate reservoir, inhibit water invasion of the oil well, improve the production effect of the oil well, improve the overall production effect of the block and have good application prospect.
Detailed Description
The present invention is further illustrated by the following examples, which are intended to be purely exemplary of the invention and are not to be construed as limiting the invention in any way.
The starting materials used in the present application are commercially available unless otherwise specified.
Example 1
Preparation of organic titanium crosslinking agent
Weighing triethanolamine, industrial alcohol and tetraisopropyl titanate in sequence according to the mass ratio of 1.2:0.6:1, mixing the triethanolamine and the alcohol, adding the tetraisopropyl titanate under the stirring condition, heating to 55 ℃, continuously stirring for reaction for 5 hours, sampling, dripping into water to be completely dissolved, and stopping the reaction to obtain the organic titanium crosslinking agent No. 1, wherein the liquid color is orange brown. Used in the next step without purification.
Example 2
Preparation of organic titanium crosslinking agent
Weighing triethanolamine, industrial alcohol and tetraisopropyl titanate in sequence according to the mass ratio of 1:0.8:0.8, mixing the triethanolamine and the alcohol, adding the tetraisopropyl titanate under the stirring condition, heating to 45 ℃, reacting for 6 hours, sampling, dripping into water to be completely dissolved, and stopping the reaction to obtain the organic titanium crosslinking agent No. 2, wherein the liquid color is orange brown. Used in the next step without purification.
Example 3
Preparation of organic titanium crosslinking agent
Weighing triethanolamine, industrial alcohol and tetraisopropyl titanate in sequence according to the mass ratio of 2:0.8:0.4, mixing the triethanolamine and the alcohol, adding the tetraisopropyl titanate under the stirring condition, heating to 60 ℃, reacting for 3 hours, sampling, dripping into water to be completely dissolved, and stopping the reaction to obtain the organic titanium crosslinking agent No. 3, wherein the liquid color of the organic titanium crosslinking agent is orange brown. Used in the next step without purification.
Example 4
Preparation of slow swelling granules
Taking 10 parts by mass of chitin, 5 parts by mass of acrylamide monomer, 3 parts by mass of acrylic acid monomer, 0.03 part by mass of organic phthalein cross-linking agent 1# and 0.02 part by mass of potassium persulfate, and the balance of water, wherein the total mass is 100 parts by mass.
Adding weighed acrylic acid and acrylamide into a four-mouth bottle, adding water to dissolve, adding chitin, continuously stirring to fully dissolve, and introducing N2After 10 minutes, adding weighed potassium persulfate and organic phthalein cross-linking agent No. 1, fully and uniformly stirring, and continuously introducing N during the period25 minutes, a mixture system was obtained. Sealing the prepared mixture system, putting the mixture system into a thermostat (BINDER ED115) at 50 ℃, and reacting for 4 hours under a heating condition to obtain a slow swelling gel block; and (3) putting the prepared slow swelling gel block into an oven (BINDER ED115) at 85 ℃ for drying, and crushing into 100-mesh and 120-mesh particles by using a crusher (ZT-600 type), thereby obtaining the slow swelling particles 4 #.
Example 5
Preparation of slow swelling granules
Based on 100 parts by mass of the total amount, 55 parts by mass of chitin, 10 parts by mass of an acrylamide monomer, 5 parts by mass of an acrylic acid monomer, 0.5 part by mass of an organic phthalein cross-linking agent 1#, 0.15 part by mass of potassium persulfate and the balance of water are taken.
Adding weighed acrylic acid and acrylamide into a four-mouth bottle, adding water to dissolve, adding chitin, continuously stirring to fully dissolve, and introducing N2After 15 minutes, adding weighed potassium persulfate and organic phthalein cross-linking agent No. 1, fully and uniformly stirring, and continuously introducing N during the period215 minutes, a mixture system was obtained. Sealing the prepared mixture system, putting the mixture system into a thermostat (BINDER ED115) at 75 ℃, and reacting for 6 hours under a heating condition to obtain a slow swelling gel block; and (3) putting the prepared slow swelling gel block into an oven (BINDER ED115) at 85 ℃ for drying, and crushing into 100-mesh and 120-mesh particles by using a crusher (ZT-600 type), thereby obtaining the slow swelling particles 5 #.
Example 6
Preparation of slow swelling granules
Taking 25 parts by mass of chitin, 8 parts by mass of acrylamide monomer, 5 parts by mass of acrylic acid monomer, 0.15 part by mass of organic phthalein cross-linking agent 1# and 0.1 part by mass of potassium persulfate, and the balance of water, wherein the total mass is 100 parts by mass.
Adding weighed acrylic acid and acrylamide into a four-mouth bottle, adding water to dissolve, adding chitin, continuously stirring to fully dissolve, and introducing N2After 10 minutes, adding weighed potassium persulfate and organic phthalein cross-linking agent No. 1, fully and uniformly stirring, and continuously introducing N during the period215 minutes, a mixture system was obtained. Sealing the prepared mixture system, putting the mixture system into a thermostat (BINDER ED115) at 75 ℃, and reacting for 5 hours under a heating condition to obtain a slow swelling gel block; and (3) putting the prepared slow swelling gel block into an oven (BINDER ED115) at 85 ℃ for drying, and crushing into 100-mesh and 120-mesh particles by using a crusher (ZT-600 type), thereby obtaining the slow swelling particles 6 #.
Example 7
Preparation of slow swelling granules
According to the total amount of 100 parts, 10 parts by mass of chitosan, 5 parts by mass of acrylamide monomer, 3 parts by mass of acrylic acid monomer, 0.03 part by mass of organic phthalein cross-linking agent 2#, 0.02 part by mass of ammonium persulfate and the balance of water are taken.
Adding weighed acrylic acid and acrylamide into a four-mouth bottle, adding water to dissolve, adding chitosan, continuously stirring to fully dissolve, and introducing N2After 10 minutes, adding weighed ammonium persulfate and organic phthalein cross-linking agent No. 2, fully and uniformly stirring, and continuously introducing N during the period2For 5 minutes. Sealing the prepared mixture system, putting the mixture system into a thermostat (BINDERED115) at 50 ℃, and reacting for 4 hours under a heating condition to obtain a slow swelling gel block; and (3) putting the prepared slow swelling gel block into an oven (BINDER ED115) at 85 ℃ for drying, and crushing into 100-mesh and 120-mesh particles by using a crusher (ZT-600 type), thereby obtaining the slow swelling particles 7 #.
Example 8
Preparation of slow swelling granules
According to the total amount of 100 parts by mass, 55 parts by mass of chitosan, 10 parts by mass of acrylamide monomer, 5 parts by mass of acrylic acid monomer, 0.5 part by mass of organic phthalein cross-linking agent 3#, 0.15 part by mass of ammonium persulfate and the balance of water are taken.
Adding weighed acrylic acid and acrylamide into a four-mouth bottle, adding water to dissolve, and adding a shellStirring the polysaccharide to dissolve it sufficiently, introducing N215 minutes later, then adding weighed ammonium persulfate and organic phthalein cross-linking agent No. 3, fully and uniformly stirring, and continuously introducing N during the period2For 15 minutes. Sealing the prepared mixture system, putting the mixture system into a thermostat (BINDERED115) at 75 ℃, and reacting for 6 hours under a heating condition to obtain a slow swelling gel block; and (3) putting the prepared slow swelling gel block into an oven (BINDER ED115) at 85 ℃ for drying, and crushing into 100-mesh and 120-mesh particles by using a crusher (ZT-600 type), thereby obtaining the slow swelling particles 8 #.
Example 9
Preparation of slow swelling granules
According to the total amount of 100 parts by mass, 25 parts by mass of carboxymethyl cellulose, 8 parts by mass of acrylamide monomer, 5 parts by mass of acrylic acid monomer, 0.15 part by mass of organic phthalein cross-linking agent 1#, 0.1 part by mass of sodium persulfate and the balance of water are taken.
Adding weighed acrylic acid and acrylamide into a four-mouth bottle, adding water to dissolve, adding chitosan, continuously stirring to fully dissolve, and introducing N2After 10 minutes, adding weighed sodium persulfate and organic phthalein cross-linking agent No. 1, fully and uniformly stirring, and continuously introducing N during the period2For 15 minutes. Sealing the prepared mixture system, putting the mixture system into a thermostat (BINDERED115) at 75 ℃, and reacting for 5 hours under a heating condition to obtain a slow swelling gel block; and (3) putting the prepared slow swelling gel block into an oven (BINDER ED115) at 85 ℃ for drying, and crushing into 100-mesh and 120-mesh particles by using a crusher (ZT-600 type), thereby obtaining the slow swelling particles 9 #.
Example 10
Preparation of slow swelling granules
According to the total amount of 100 parts by mass, 10 parts by mass of soluble starch, 5 parts by mass of acrylamide monomer, 3 parts by mass of acrylic acid monomer, 0.03 part by mass of organic phthalein cross-linking agent 1#, 0.02 part by mass of ammonium persulfate and the balance of water are taken.
Adding weighed acrylic acid and acrylamide into a four-mouth bottle, adding water to dissolve, adding soluble starch, continuously stirring to fully dissolve, and introducing N2After 10 minutes, the weighed ammonium persulfate and organic phthalein are added for crosslinkingAgent No. 1, and stirring thoroughly, while continuing to introduce N2For 5 minutes. Sealing the prepared mixture system, putting the mixture system into a thermostat (BINDER ED115) at 50 ℃, and reacting for 4 hours under a heating condition to obtain a slow swelling gel block; and (3) putting the prepared slow swelling gel block into an oven (BINDER ED115) at 85 ℃ for drying, and crushing into 100-mesh and 120-mesh particles by using a crusher (ZT-600 type), thereby obtaining the slow swelling particles of 10 #.
Example 11
Preparation of slow swelling granules
According to the total amount of 100 parts by mass, 55 parts by mass of soluble starch, 10 parts by mass of acrylamide monomer, 5 parts by mass of acrylic acid monomer, 0.5 part by mass of organic phthalein cross-linking agent 1#, 0.15 part by mass of ammonium persulfate and the balance of water are taken.
Adding weighed acrylic acid and acrylamide into a four-mouth bottle, adding water to dissolve, adding soluble starch, continuously stirring to fully dissolve, and introducing N215 minutes later, then adding weighed ammonium persulfate and organic phthalein cross-linking agent No. 1, fully and uniformly stirring, and continuously introducing N during the period2For 15 minutes. Sealing the prepared mixture system, putting the mixture system into a thermostat (BINDER ED115) at 75 ℃, and reacting for 6 hours under a heating condition to obtain a slow swelling gel block; and (3) putting the prepared slow swelling gel block into an oven (BINDER ED115) at 85 ℃ for drying, and crushing into 100-mesh and 120-mesh particles by using a crusher (ZT-600 type), thereby obtaining the slow swelling particles 11 #.
Example 12
Preparation of slow swelling granules
According to the total amount of 100 parts by mass, 25 parts by mass of soluble starch, 8 parts by mass of acrylamide monomer, 5 parts by mass of acrylic acid monomer, 0.15 part by mass of organic phthalein cross-linking agent 1#, 0.1 part by mass of ammonium persulfate and the balance of water are taken.
Adding weighed acrylic acid and acrylamide into a four-mouth bottle, adding water to dissolve, adding soluble starch, continuously stirring to fully dissolve, and introducing N2After 10 minutes, adding weighed ammonium persulfate and organic phthalein cross-linking agent No. 1, fully and uniformly stirring, and continuously introducing N during the period2For 15 minutes. Sealing the prepared mixture system, and placingReacting in a thermostat (BINDER ED115) at 75 ℃ for 5 hours under the heating condition to obtain a slow swelling gel block; and (3) putting the prepared slow swelling gel block into an oven (BINDER ED115) at 85 ℃ for drying, and crushing into 100-mesh and 120-mesh particles by using a crusher (ZT-600 type), thereby obtaining the slow swelling particles 12 #.
Example 13
Preparation of slow swelling granules
According to the total amount of 100 parts by mass, 25 parts by mass of guar gum, 8 parts by mass of acrylamide monomer, 5 parts by mass of acrylic acid monomer, 0.15 part by mass of organic phthalein cross-linking agent 1#, 0.1 part by mass of ammonium persulfate and the balance of water are taken.
Adding weighed acrylic acid and acrylamide into a four-mouth bottle, adding water to dissolve, adding fenugreek gum, continuously stirring to fully dissolve, and introducing N2After 10 minutes, adding weighed ammonium persulfate and organic phthalein cross-linking agent No. 1, fully and uniformly stirring, and continuously introducing N during the period2For 15 minutes. Sealing the prepared mixture system, putting the mixture system into a thermostat (BINDERED115) at 75 ℃, and reacting for 5 hours under a heating condition to obtain a slow swelling gel block; and (3) putting the prepared slow swelling gel block into an oven (BINDER ED115) at 85 ℃ for drying, and crushing into 100-mesh and 120-mesh particles by using a crusher (ZT-600 type), thereby obtaining the slow swelling particles 13 #.
Example 14
Preparation of slow swelling granules
According to the total amount of 100 parts by mass, 25 parts by mass of fenugreek gum, 8 parts by mass of acrylamide monomer, 5 parts by mass of acrylic acid monomer, 0.15 part by mass of organic phthalein cross-linking agent 1#, 0.1 part by mass of ammonium persulfate and the balance of water are taken.
Adding weighed acrylic acid and acrylamide into a four-mouth bottle, adding water to dissolve, adding fenugreek gum, continuously stirring to fully dissolve, and introducing N2After 10 minutes, adding weighed ammonium persulfate and organic phthalein cross-linking agent No. 1, fully and uniformly stirring, and continuously introducing N during the period2For 15 minutes. Sealing the prepared mixture system, putting the mixture system into a thermostat (BINDERED115) at 75 ℃, and reacting for 5 hours under a heating condition to obtain a slow swelling gel block; placing the obtained gel block into an oven (BINDER) at 85 deg.CED115) and crushed into 100-mesh and 120-mesh particles by a crusher (ZT-600 type), thereby obtaining the slow swelling particles 14 #.
Example 15
Evaluation of Properties of Slow swelling particles
The experimental method comprises the following steps: 0.5g of the slow swelling granules prepared in each example was weighed, respectively, and filled in an ampoule bottle, 30mL of simulated water (total degree of mineralization 230000mg/L, Ca) was added2+、Mg2+13000mg/L), sealing the ampoule bottle, putting the ampoule bottle into an aging tank, and putting the aging tank with the ampoule bottle into an oven at 80 ℃, 120 ℃ and 140 ℃. Wherein, 30 parallel samples, namely 30 samples at 80 ℃, 120 ℃ and 140 ℃, are respectively made in the performance evaluation experiment corresponding to the slow-swelling particles prepared in each example. The particles were weighed at intervals according to table 1, filtered to remove free water, and the expansion factor was calculated according to the formula. The expansion factor is calculated as follows:
expansion factor (mass of expanded particles-mass of initial particles)/mass of initial particles
The results are shown in Table 1.
TABLE 1 evaluation of expansion retarding Properties of granules
As can be seen from Table 1, each of the examples exhibited better swelling retarding properties. The lower the temperature, the slower the expansion rate; the higher the temperature, the higher the expansion rate. But shows better delayed expansion performance and stability in the temperature range.
Example 16
Evaluation of plugging performance of expansion-retarding particles
The experimental method comprises the following steps: the 100-mesh 120-mesh slow swelling particles prepared in examples 7, 10 and 11 were randomly selected from examples 1 to 14 and weighed respectively, and simulated formation water (total salinity of 230000mg/L, Ca) was used2+、Mg2+13000mg/L) as the preparation solution, and respectively preparing the suspension into the slow swelling particle with the mass concentration of 0.20 percent. The sand-packed tubes (2.5 cm. times.30 cm) were saturated with the simulated water and their permeability was measured with a displacement apparatus (model HV-III). Then 0.05PV of slow swelling particle suspension is respectively injected into the sand-packed pipe at the injection speed of 0.3mL/min, and then the sand-packed pipe is placed at the constant temperature of 120 ℃ for 5 days, and then simulated water is respectively injected at the injection speed of 0.3mL/min to displace different water for measuring the permeability (K)b) The measured permeability K of the sand-filled pipe at the moment is calculatedfAccording to the formula η ═ 1-Kf/Kb) The plugging rate η of the slow swelling granules was calculated at 100%, and the results are shown in Table 2.
As can be seen from Table 2, the slow swelling particles still have strong plugging capability under the conditions of high temperature and high mineralization, and the plugging rate is as high as more than 95%.
TABLE 2 Slow expansion particle plugging Properties
Example 17
Implementation in situ
The site implementation is to inject three slugs into the formation by using a cement truck according to the following steps (the total volume is prepared to be 300 m)3)：
Injecting a front-mounted slug into simulated water (total mineralization is 230000mg/L, Ca) according to mass percentage concentration2+、Mg2+13000mg/L) is added with 0.8 percent of plugging agent prepared by slow swelling particles to prepare 45m3(15% of the total) is injected into the formation. Wherein, no sedimentation occurs in the preparation process.
Injecting a main body slug, adding 1.0 percent of polyacrylamide with the molecular weight of 1100 ten thousand and the hydrolysis degree of 25 percent and 0.25 percent of polyethyleneimine organic cross-linking agent into water according to the mass percentage concentration, and preparing 225m3(75% of the total), injecting into the formation;
step three, injecting a sealing slug, adding 5 percent of sodium soil, 20 percent of G-grade cement and 0.1 percent of retarder (sodium borate) into the water according to the mass percentage concentration) Preparing 30m3(10% of the total) is injected into the formation.
During the injection process, the injection speed of each slug is kept at 10m3/h。
After the oil field oil well of the embodiment is subjected to water plugging, 2214t of oil production and 7862t of water production are periodically carried out, and the comprehensive water content is 78.03%. The well wheel adopts conventional gel water plugging, 150t of oil production, 3152t of water production and 95.45 percent of comprehensive water content. Compared with the conventional water plugging method, the water plugging method of the embodiment has the advantages that the comprehensive water content is reduced by 17.42 percent compared with the conventional water plugging method in which oil is periodically increased by 2064t, and the oil increasing and water controlling effects are outstanding.
Example 18
Implementation in situ
The field implementation is that a cement truck is utilized to inject three slugs into the stratum according to the following steps:
injecting a front-mounted slug into simulated water (total mineralization is 230000mg/L, Ca) according to mass percentage concentration2+、Mg2+13000mg/L) is added with 0.2 percent of plugging agent prepared by slow swelling particles to prepare 30m3(10% of the total) is injected into the formation. Wherein, no sedimentation occurs in the preparation process.
Injecting a main body slug, adding 0.5 percent of polyacrylamide (molecular weight of 2000 ten thousand and hydrolysis degree of 30 percent) and 0.15 percent of polyethyleneimine organic cross-linking agent into water according to mass percentage concentration, and preparing 225m3(75% of the total), injecting into the formation;
step three, injecting a sealing slug, adding 5 percent of sodium soil, 20 percent of G-grade cement and 0.01 percent of retarder (sodium borate) into water according to the mass percentage concentration, and preparing 45m3(15% of the total) is injected into the formation.
During the injection process, the injection speed of each slug is kept at 9m3/h。
After the oil field oil well of the embodiment is subjected to water plugging, 1876t of oil production, 6528t of water production and 77.67% of comprehensive water content are periodically produced. The well-logging wheel adopts conventional gel water plugging, oil production 102t, water production 4427t and comprehensive water content 97.75 percent. Compared with the conventional water plugging method, the water plugging method of the embodiment has the advantages that the comprehensive water content is reduced by 20.08 percent compared with the conventional water plugging method which increases oil at 1774t periodically, and the oil increasing and water controlling effects are outstanding.
Example 19
Implementation in situ
The field implementation is that a cement truck is utilized to inject three slugs into the stratum according to the following steps:
injecting a front-mounted slug into simulated water (total mineralization is 230000mg/L, Ca) according to mass percentage concentration2+、Mg2+13000mg/L) is added with the plugging agent prepared by 2.0 percent of slow swelling particles to prepare 75m3(20% of the total) is injected into the formation. Wherein, no sedimentation occurs in the preparation process.
Injecting a main body slug, adding 1.5 percent of polyacrylamide with the molecular weight of 500 ten thousand and the hydrolysis degree of 15 percent and 0.35 percent of polyethyleneimine organic cross-linking agent into water according to the mass percentage concentration, and preparing 180m3(60% of the total), injecting into the formation;
step three, injecting a sealing slug, adding 10% of sodium soil, 40% of G-grade cement and 1% of retarder (sodium borate) into water according to the mass percentage concentration, and preparing 45m3(15% of the total) is injected into the formation.
During the injection process, the injection speed of each slug is kept at 9m3/h。
After the oil field oil well of the embodiment is subjected to water plugging, 3581t of oil production, 11253t of water production and 75.86% of comprehensive water content are obtained periodically. The well wheel adopts conventional gel water plugging, oil production is 280t, water production is 5632t, and comprehensive water content is 95.26%. Compared with the conventional water plugging method, the water plugging method of the embodiment has the advantages that the comprehensive water content is reduced by 19.4 percent compared with the conventional water plugging method in which oil is added for 3301t periodically, and the oil-adding and water-controlling effects are outstanding.
While the present application has been described with reference to specific embodiments, those skilled in the art will appreciate that various changes can be made without departing from the true spirit and scope of the present application. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, and method to the objective, spirit and scope of the present application. All such modifications are intended to be included within the scope of the claims of this application.
Claims (9)
1. A method for water shutoff of a reservoir oil well comprises the following steps:
1) injecting a first plugging agent into the oil well at the front section plug, wherein the first plugging agent is a first mixture comprising expansion-slowing particles and water; the preparation method of the slow swelling particles comprises the following steps:
1-1) obtaining reaction raw materials, wherein the reaction raw materials comprise a graftable copolymer, acrylic acid, acrylamide, a cross-linking agent, an initiator and water;
1-2) dissolving the acrylic acid and acrylamide in water, adding the graft copolymer, fully dissolving, and introducing N2Then adding the initiator and the cross-linking agent, mixing uniformly, and continuously introducing N during mixing2Obtaining a mixture system;
1-3) reacting the mixed system under the heating condition to obtain a slow swelling gel block;
1-4) drying, crushing and sieving the slow swelling gel block to obtain slow swelling particles;
2) injecting a second plugging agent into the oil well at the main body slug, wherein the second plugging agent is a second mixture comprising polyacrylamide, an organic cross-linking agent and water; wherein the polyacrylamide has a degree of hydrolysis of 15% to 30% and a molecular weight of 500 to 2000 ten thousand;
3) and injecting a third plugging agent into the oil well at the sealing slug, wherein the third plugging agent is a third mixture comprising sodium soil, cement, a retarder and water.
2. The method according to claim 1, wherein the content of the slow swelling particles in the first mixture is 0.2 to 2% by mass.
3. The method according to claim 1 or 2, characterized in that the polyacrylamide is contained in the second mixture in a mass percentage of 0.5% to 1.5%; the polyethyleneimine is present in the second mixture in an amount of 0.15% to 0.35%.
4. The method according to any one of claims 1 to 3, characterized in that the content of the sodium soil in the third mixture is 5 to 10% in mass percent; the content of the cement in the third mixture is 20% to 40%; the retarder is present in the third mixture in an amount of 0.01% to 1%.
5. The method according to any one of claims 1 to 4, characterized in that the total amount of the first, second and third plugging agent does not exceed 500m3。
6. The method according to any one of claims 1 to 5, characterized in that the first plugging agent is used in an amount of 10 to 25% by volume of the total amount; and/or
The dosage of the second plugging agent is 60 to 75 percent of the total dosage; and/or
The dosage of the third plugging agent is 10 to 15 percent of the total dosage.
7. The method according to any one of claims 1 to 6, wherein the injection speed of the plugging agent in step 1), step 2) and step 3) is 3 to 15m independently3H, preferably 9 to 10m3/h。
8. The method according to any one of claims 1 to 7, wherein the cement is a grade G cement.
9. A method according to any one of claims 1 to 8, characterised in that the retarder is a borate and/or a silicate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811242608.XA CN111087997A (en) | 2018-10-24 | 2018-10-24 | Method for blocking water in oil reservoir and oil well |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811242608.XA CN111087997A (en) | 2018-10-24 | 2018-10-24 | Method for blocking water in oil reservoir and oil well |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111087997A true CN111087997A (en) | 2020-05-01 |
Family
ID=70392074
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811242608.XA Pending CN111087997A (en) | 2018-10-24 | 2018-10-24 | Method for blocking water in oil reservoir and oil well |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111087997A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114427374A (en) * | 2020-09-21 | 2022-05-03 | 中国石油化工股份有限公司 | Well group cooperative water control method for solution reservoir |
| CN114517657A (en) * | 2020-11-20 | 2022-05-20 | 中国石油化工股份有限公司 | Binary composite water control process for high-temperature high-salinity bottom water reservoir |
| CN114736661A (en) * | 2022-04-28 | 2022-07-12 | 中海石油(中国)有限公司 | Weak-consolidation large-pore passage treatment system and preparation method and application thereof |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4140183A (en) * | 1978-02-13 | 1979-02-20 | Union Oil Company Of California | Micellar flooding process for heterogeneous reservoirs |
| US4515216A (en) * | 1983-10-11 | 1985-05-07 | Halliburton Company | Method of using thixotropic cements for combating lost circulation problems |
| CN1888374A (en) * | 2005-06-28 | 2007-01-03 | 中国石油天然气股份有限公司 | High-temperature and High-Salt resisting gel water packing-off method |
| US20070187098A1 (en) * | 2006-02-14 | 2007-08-16 | Putzig Donald E | Permeable zone and leak plugging using cross-linking composition comprising delay agent |
| CN101121880A (en) * | 2007-08-01 | 2008-02-13 | 成都市互利达实业有限公司 | Natural macromolecule modified starch profile control agent for oil field |
| CN103614123A (en) * | 2013-10-21 | 2014-03-05 | 中国石油大学(华东) | Polyethyleneimine jelly profile-control water-blocking agent |
| CN104100224A (en) * | 2013-04-03 | 2014-10-15 | 中国石油天然气股份有限公司 | Oil well water plugging method |
-
2018
- 2018-10-24 CN CN201811242608.XA patent/CN111087997A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4140183A (en) * | 1978-02-13 | 1979-02-20 | Union Oil Company Of California | Micellar flooding process for heterogeneous reservoirs |
| US4515216A (en) * | 1983-10-11 | 1985-05-07 | Halliburton Company | Method of using thixotropic cements for combating lost circulation problems |
| CN1888374A (en) * | 2005-06-28 | 2007-01-03 | 中国石油天然气股份有限公司 | High-temperature and High-Salt resisting gel water packing-off method |
| US20070187098A1 (en) * | 2006-02-14 | 2007-08-16 | Putzig Donald E | Permeable zone and leak plugging using cross-linking composition comprising delay agent |
| CN101121880A (en) * | 2007-08-01 | 2008-02-13 | 成都市互利达实业有限公司 | Natural macromolecule modified starch profile control agent for oil field |
| CN104100224A (en) * | 2013-04-03 | 2014-10-15 | 中国石油天然气股份有限公司 | Oil well water plugging method |
| CN103614123A (en) * | 2013-10-21 | 2014-03-05 | 中国石油大学(华东) | Polyethyleneimine jelly profile-control water-blocking agent |
Non-Patent Citations (1)
| Title |
|---|
| 贾虎等: "裂缝性油藏控水堵水方法研究与应用", 《地质科技情报》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114427374A (en) * | 2020-09-21 | 2022-05-03 | 中国石油化工股份有限公司 | Well group cooperative water control method for solution reservoir |
| CN114517657A (en) * | 2020-11-20 | 2022-05-20 | 中国石油化工股份有限公司 | Binary composite water control process for high-temperature high-salinity bottom water reservoir |
| CN114736661A (en) * | 2022-04-28 | 2022-07-12 | 中海石油(中国)有限公司 | Weak-consolidation large-pore passage treatment system and preparation method and application thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106479465B (en) | Profile control water shutoff agent and preparation method and application thereof | |
| CN100543106C (en) | The preparation of composite cation blocking agent and stifled poly-using method | |
| CN102587858B (en) | Method for blocking water for fracture and hole type reservoir | |
| CN103013480A (en) | Modified petroleum coke granule composite profile control water blocking agent and multi-round bidirectional blocking control technology | |
| CN106479466B (en) | Profile control water shutoff agent and preparation method and application thereof | |
| CN104629697B (en) | A kind of heatproof frozen glue | |
| CN111087998B (en) | Slow-expansion particles and preparation method thereof | |
| CN103232839A (en) | Water shutoff agent applicable to high-temperature high-salt oil reservoir water shutoff profile control | |
| CN111087997A (en) | Method for blocking water in oil reservoir and oil well | |
| CN102816558A (en) | Plugging agent for deep profile control and water plugging and preparation method thereof | |
| CN104087275A (en) | High-temperature-resistant and high-salt-resistant fine gel particle as profile control agent as well as preparation method and application of fine gel particle | |
| CN102558469B (en) | Cross-linking agent for profile control and oil displacement for high-temperature oil reservoir, as well as preparation method and application for same | |
| CN107739599A (en) | A kind of high temperature low-density water shutoff agent and preparation method thereof and onsite application method | |
| CN102746835B (en) | Carbonatite oil well density selectivity water shutoff agent and preparation process thereof | |
| CN108675705B (en) | Oil-containing sludge channeling sealing composition, oil-containing sludge channeling sealing agent, and preparation method and application thereof | |
| CN104927005B (en) | A kind of alkaline-resisting profile control agent of pre-crosslinked gel volume expansion grain and preparation method thereof and purposes | |
| CN103980872A (en) | Environmental-friendly gel plugging agent applicable to low-temperature oil pool and applications of gel plugging agent | |
| CN102618232B (en) | Plugging agent for fractured-vuggy oil reservoir | |
| CN102102012A (en) | Selective plugging agent for horizontal well and preparation method thereof | |
| CN114736661A (en) | Weak-consolidation large-pore passage treatment system and preparation method and application thereof | |
| CN102153994B (en) | High-temperature miscible phase temporary plugging and sealing agent and preparation method thereof | |
| CN104481478A (en) | Method for plugging large pore passage in polymer flooding corresponding oil well to prevent polymer breakthrough and treating agent used by method | |
| CN112983343A (en) | Water plugging method for oil well of carbonate rock solution-breaking oil reservoir | |
| CN114426826B (en) | Plugging slug composition, oil displacement slug composition, profile control and profile control agent and application | |
| RU2405927C1 (en) | Method for liquidation of absorption zones in well |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20200501 |
|
| WD01 | Invention patent application deemed withdrawn after publication |