CN114250067B - Temporary plugging agent for natural gas hydrate drilling fluid and preparation method thereof - Google Patents
Temporary plugging agent for natural gas hydrate drilling fluid and preparation method thereof Download PDFInfo
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- CN114250067B CN114250067B CN202111607911.7A CN202111607911A CN114250067B CN 114250067 B CN114250067 B CN 114250067B CN 202111607911 A CN202111607911 A CN 202111607911A CN 114250067 B CN114250067 B CN 114250067B
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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
- C09K8/02—Well-drilling compositions
- C09K8/03—Specific additives for general use in well-drilling compositions
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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
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
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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
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
- C09K8/516—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls characterised by their form or by the form of their components, e.g. encapsulated material
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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
- C09K8/56—Compositions for consolidating loose sand or the like around wells without excessively decreasing the permeability thereof
Abstract
The invention discloses a temporary plugging agent for natural gas hydrate drilling fluid and a preparation method thereof. The temporary plugging agent is of a shell-core structure and comprises inner core ceramic particles with porous channels and a polymer shell grafted outside the inner core through a silane coupling agent; the porous channel comprises a biological enzyme polymer micelle; the components of the polymeric shell include a cellulose derivative; the biological enzyme polymer micelle is formed by coating biological enzyme in a hydrophobic core of an amphiphilic block copolymer, and the amphiphilic block copolymer comprises a hydrophilic block A and a hydrophobic block B. The temporary plugging agent has the effects of reservoir protection and synergistic sand prevention, and the degradation time of the graft polymer on the surface of the ceramic particles can be regulated and controlled by biological enzyme.
Description
Technical Field
The invention relates to the field of natural gas hydrate drilling fluid, in particular to a temporary plugging agent for natural gas hydrate drilling fluid and a preparation method thereof.
Background
The natural gas hydrate is used as a potential oil-gas replacing resource and has the characteristics of wide distribution range, large energy density and the like. Sea area natural gas hydrate drilling and production, especially drilling and production of wells with complex structures such as horizontal wells and the like face a series of major technical problems, wherein the problems of instability of well walls and damage of reservoir stratums caused by invasion of drilling fluid and blockage of produced gas sand are not effectively solved, and development of temporary plugging materials for hydrate drilling fluid, which have plugging capability, good reservoir stratum protection effect and sand prevention effect, is urgently needed.
Disclosure of Invention
The invention aims to provide a temporary plugging agent for natural gas hydrate drilling fluid and a preparation method thereof.
Aiming at the problems of stability of the well wall of a natural gas hydrate stratum, reservoir damage and sand production blockage in a sea area, the invention prepares the temporary plugging agent for the natural gas hydrate drilling fluid with the effects of reservoir protection and synergistic sand prevention, and can regulate and control the degradation time of the graft polymer on the surface of the ceramic particles through biological enzyme.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a temporary plugging agent for natural gas hydrate drilling fluid, as shown in figure 1, wherein the temporary plugging agent is of a shell-core structure and comprises inner core ceramic particles with porous channels and a polymer shell grafted outside the inner core through a silane coupling agent; the porous channel comprises a biological enzyme polymer micelle;
the components of the polymeric shell include a cellulose derivative;
the biological enzyme polymer micelle is formed by coating biological enzyme in a hydrophobic core of an amphiphilic block copolymer, and the amphiphilic block copolymer comprises a hydrophilic block A and a hydrophobic block B.
According to the temporary plugging agent of the present invention, preferably, the cellulose derivative is selected from one or a combination of two or more of carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC) and hydroxypropyl cellulose (HPC).
According to the temporary plugging agent of the present invention, preferably, the hydrophilic block a is selected from polyethylene glycol, polyethylene glycol monomethyl ether, hyaluronic acid or polyacrylic dextran; the hydrophobic block B is selected from polyglycolide, polylactide, polycaprolactone, poly (glycolide-co-lactide), polycarbonate, polyesteramide or polyetherester.
According to the temporary plugging agent of the present invention, preferably, the mass ratio of the hydrophilic block a to the hydrophobic block B is 4.
According to the temporary plugging agent of the present invention, preferably, the mass ratio of the biological enzyme to the amphiphilic block copolymer is 1.
According to the temporary plugging agent of the present invention, preferably, the biological enzyme is selected from one or a combination of two or more of cellulase, hemicellulase, esterase and industrial protease.
According to the temporary plugging agent of the present invention, preferably, the silane coupling agent is selected from one or a combination of two or more of γ -aminopropyltriethoxysilane (KH-550), γ - (2, 3-glycidoxy) propyltrimethoxysilane (KH-560), γ -methacryloxypropyltrimethoxysilane (KH-570), vinyltrimethoxysilane (A-171), vinyltris (. Beta. -methoxyethoxy) silane (A-172).
According to the temporary plugging agent of the present invention, preferably, the average particle size of the bio-enzyme polymer micelle is 50nm to 220nm.
According to the temporary plugging agent of the present invention, preferably, the ceramic particles have an average particle diameter of 40 to 60 μm and an average pore diameter of 3 to 5 μm.
In another aspect, the present invention provides a preparation method of the temporary plugging agent for natural gas hydrate drilling fluid, as shown in fig. 1, the preparation method includes the following steps:
preparing the biological enzyme polymer micelle by adopting a thin film hydration method;
soaking the biological enzyme polymer micelle and the ceramic particles in distilled water together to enable the biological enzyme polymer micelle to enter a porous channel of the ceramic particles, and airing after soaking to obtain the inner core ceramic particles;
modifying the core ceramic particles with a silane coupling agent;
and carrying out polymerization reaction on the modified core ceramic particles and cellulose derivatives under the action of an initiator to complete grafting so as to form the polymer shell, thus obtaining the temporary plugging agent.
According to the preparation method of the present invention, preferably, the thin film hydration method specifically includes:
dissolving a biological enzyme and an amphiphilic block copolymer in an organic solvent;
removing the organic solvent by using a rotary evaporator, preparing a uniform film, and drying in vacuum until the organic solvent is removed;
dissolving the film in pure water or phosphate buffer solution, hydrating for 2-10 h, performing ultrasonic treatment to form stable emulsion, filtering by using 0.45-micron and 0.22-micron films in sequence, and performing freeze drying to obtain the biological enzyme polymer micelle.
In the above thin film hydration method, preferably, the organic solvent is one or a combination of two or more selected from the group consisting of ethyl acetate, dichloromethane, chloroform, acetonitrile, and tetrahydrofuran.
In the above thin film hydration method, the amount ratio of the organic solvent to the biological enzyme is preferably (1.0 to 2.0) mL:1mg.
In the above film hydration method, preferably, when the film is dissolved in pure water or a phosphate buffer, the mass percentage of the film is 0.1% to 10%.
In the above thin film hydration method, preferably, the temperature of the hydration is 15 to 35 ℃.
According to the preparation method of the present invention, preferably, the mass ratio of the bio-enzyme polymer micelle, the ceramic particle and the distilled water is (1 to 5): (10-50): (100-500), preferably (1-5): 10:100, respectively; the soaking time is 24-48 h, the stirring is carried out once every 1h of soaking, and finally the soaking liquid is repeatedly filtered and filtered for 3-5 times to complete the soaking.
According to the preparation method of the present invention, preferably, the step of modifying the inner core ceramic particle with a silane coupling agent specifically includes:
mixing 15-20 parts by weight of the core ceramic particles, 150-200 parts by weight of anhydrous ethanol and 10-20 parts by weight of pure water, adjusting the pH to 7.5-9 by ammonia water, and stirring for 30-60 min;
adding silane coupling agent with 15-20 wt% of ceramic particles, performing ultrasonic treatment for 30-60 min, reacting at 15-35 ℃ for 4-6 h, filtering after the reaction is finished, washing the solid and drying.
According to the production method of the present invention, preferably, the step of forming the polymer housing specifically includes:
mixing the modified core ceramic particles, cellulose derivatives, an initiator and pure water, and reacting for 4-6 h at 15-35 ℃; and after the reaction is finished, centrifuging, washing the solid, drying, and performing ball milling dispersion to obtain the temporary plugging agent.
In the above step of forming the polymer shell, preferably, the concentration of the cellulose derivative in the system is 1wt% to 3wt%.
In the above step of forming the polymer shell, preferably, the initiator is used in an amount of 0.4wt% to 0.6wt% of the cellulose derivative.
In the above step of forming the polymer shell, preferably, the initiator is potassium persulfate.
The invention has the following beneficial effects:
1) The invention provides a temporary plugging agent for natural gas hydrate drilling fluid, which can be controlled by biological enzyme, aiming at the well wall instability and reservoir damage in the sea natural gas hydrate drilling process, in particular to a complex structure well drilling process.
2) The recovery and communication of the gas and water transportation channel are realized through the degradation of the polymer shell on the surface of the ceramic particles in the natural gas hydrate exploitation process; the degradation starting time of the biological enzyme to the outer graft polymer shell can be controlled by the amphiphilic block polymer micelle to form a 'buffer period' of 20-50 d, and the 'buffer period' can be transported, stored and put into a well; controlling the degradation time by controlling the amount of the graft polymer in the shell again, thereby controlling the recovery time of the porous channel of the ceramic particles; the polymer is degraded under the action of biological enzyme, and no substance harmful to biology is generated after degradation, so that the polymer has environmental protection.
3) After the temporary plugging agent is unblocked, in the process of exploiting the natural gas hydrate, gas and liquid phases pass through pores with the average diameter of ceramic particles of 5 mu m, and solid sand particles in a reservoir are prevented by the pores from being greatly transferred to a region close to a well wall to form sand blocking, so that an effective synergistic sand prevention effect is achieved.
4) The temporary plugging agent for the natural gas hydrate drilling fluid provided by the invention is easy to obtain raw materials, mild in reaction conditions, convenient to control and good in large-scale industrial production prospect.
5) The temporary plugging agent provided by the invention can be directly used in low-temperature hydrate water-based drilling fluid, can play roles in protecting a reservoir and cooperatively preventing sand while stabilizing a well wall, and has important significance in realizing safe and efficient drilling and production of sea natural gas hydrate.
Drawings
FIG. 1 is a schematic diagram of the preparation process and structure of the temporary plugging agent for natural gas hydrate drilling fluid of the invention.
Detailed Description
In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.
All numerical designations of the invention (e.g., temperature, time, concentration, weight, and the like, including ranges for each) may generally be approximations that vary (+) or (-) in increments of 0.1 or 1.0 as appropriate. All numerical designations should be understood to be preceded by the term "about".
Example 1:
the temporary plugging agent A for the natural gas hydrate drilling fluid capable of being controlled by the biological enzyme is prepared by the embodiment 1 The method comprises the following specific steps:
dissolving biological enzyme (esterase and cellulase in a mass ratio of 1: 1mg. Removing ethyl acetate by using a rotary evaporator, preparing a uniform film, and then drying in vacuum until the ethyl acetate is removed; dissolving the film in pure water, wherein the mass percent of the film is 5%, hydrating for 5h at 20 ℃ to form stable emulsion by ultrasound, filtering by using 0.45 mu m and 0.22 mu m films in sequence, and freeze-drying to obtain the biological enzyme polymer micelle.
And (2) soaking the prepared biological enzyme polymer micelle and ceramic particles in distilled water together, wherein the mass ratio of the biological enzyme polymer micelle to the ceramic particles to the distilled water is 1:10:100, soaking for 24 hours, stirring once every 1 hour of soaking, finally repeatedly performing suction filtration for 3 times by using a soaking solution, and drying to obtain the core ceramic particles.
Taking 15g of core ceramic particles, adding 150mL of absolute ethyl alcohol and 10mL of pure water, adjusting the pH value to 8 by ammonia water, and stirring for 30min; adding KH-560 (gamma- (2, 3-epoxypropoxy) propyl trimethoxy silane) with the weight percent of ceramic particles, performing ultrasonic treatment for 30min, transferring the mixture into a three-neck flask, stirring the mixture for reaction for 4h at the temperature of 15 ℃, taking out the mixture after the reaction is finished, filtering the mixture, washing the solid, and drying the solid to finish the modification.
Taking 20g of the prepared modified ceramic particles, 200mL of pure water, carboxymethyl cellulose (1 wt% of pure water), and potassium persulfate (0.4 wt% of cellulose derivatives), and reacting at a constant temperature of 20 ℃ for 4h; after the reaction is finished, taking out, centrifuging, washing, drying, ball milling and dispersing to obtain a product A 1 。
Example 2:
the embodiment prepares a temporary plugging agent A for natural gas hydrate drilling fluid capable of being controlled by biological enzyme 2 The method comprises the following specific steps:
dissolving biological enzyme (esterase and cellulase in a mass ratio of 1: 1mg. Removing dichloromethane by using a rotary evaporator, preparing a uniform film, and drying in vacuum until dichloromethane is removed; dissolving the film in phosphate buffer solution, hydrating the film for 5h at 20 ℃ to form stable emulsion by ultrasound, filtering the emulsion by using 0.45 mu m and 0.22 mu m films in sequence, and freeze-drying the filtered emulsion to obtain the biological enzyme polymer micelle.
The prepared biological enzyme polymer micelle and ceramic particles are soaked in distilled water together, and the mass ratio of the biological enzyme polymer micelle to the ceramic particles to the distilled water is 2:10:100, soaking for 36 hours, stirring once every 1 hour, repeatedly filtering for 4 times by using a soaking solution, and airing to obtain the core ceramic particles.
Taking 15g of core ceramic particles, adding 150mL of absolute ethyl alcohol and 10mL of pure water, adjusting the pH value to 8.5 by ammonia water, and stirring for 30min; adding 20wt% of A-171 (vinyl trimethoxy silane) of ceramic particles, carrying out ultrasonic treatment for 30min, transferring the mixture into a three-neck flask, stirring the mixture at 15 ℃ for reaction for 4h, taking out the mixture after the reaction is finished, filtering the mixture, washing the solid, and drying the solid to finish modification.
Taking 20g of the prepared modified ceramic particles, 200mL of pure water, hydroxyethyl cellulose (1 wt% of the pure water), and potassium persulfate (0.4 wt% of the cellulose derivative), and reacting at a constant temperature of 20 ℃ for 4 hours; after the reaction is finished, taking out, centrifuging, washing, drying, ball milling and dispersing to obtain a product A 2 。
Example 3:
the temporary plugging agent A for the natural gas hydrate drilling fluid capable of being controlled by the biological enzyme is prepared by the embodiment 3 The method comprises the following specific steps:
dissolving biological enzymes (hemicellulase and esterase in a mass ratio of 1: 1mg. Removing chloroform by using a rotary evaporator, preparing a uniform film, and drying in vacuum until the chloroform is removed completely; dissolving the film in phosphate buffer solution, wherein the mass percent of the film is 5%, hydrating for 5h at 25 ℃ to form stable emulsion by ultrasound, filtering by using 0.45 mu m and 0.22 mu m films in sequence, and freeze-drying to obtain the biological enzyme polymer micelle.
The prepared biological enzyme polymer micelle and ceramic particles are soaked in distilled water together, and the mass ratio of the biological enzyme polymer micelle to the ceramic particles to the distilled water is 3:10:100, soaking for 48 hours, stirring once every 1 hour, repeatedly filtering for 5 times by using a soaking solution, and airing to obtain the core ceramic particles.
Taking 20g of core ceramic particles, adding 200mL of absolute ethyl alcohol and 20mL of pure water, adjusting the pH value to 9 by ammonia water, and stirring for 30min; adding 15wt% of ceramic particles A-172 (vinyl tri (beta-methoxyethoxy) silane), carrying out ultrasonic treatment for 30min, transferring the mixture into a three-neck flask, stirring the mixture at 25 ℃ for reaction for 4h, taking out the mixture after the reaction is finished, filtering the mixture, washing the solid, and drying the solid to finish the modification.
Taking 20g of the prepared modified ceramic particles, 200mL of pure water, hydroxypropyl cellulose (2 wt% of the pure water), and potassium persulfate (0.4 wt% of the cellulose derivative), and reacting at a constant temperature of 25 ℃ for 4 hours; after the reaction is finished, taking out, centrifuging, washing, drying, ball milling and dispersing to obtain a product A 3 。
Example 4:
the temporary plugging agent A for the natural gas hydrate drilling fluid capable of being controlled by the biological enzyme is prepared by the embodiment 4 The method comprises the following specific steps:
dissolving biological enzyme (esterase and cellulase in a mass ratio of 1: 1mg. Removing tetrahydrofuran by using a rotary evaporator, preparing a uniform film, and then drying in vacuum until chloroform is removed; dissolving the film in phosphate buffer solution, hydrating the film for 5h at 25 ℃ to form stable emulsion by ultrasound, filtering the emulsion by using 0.45 mu m and 0.22 mu m films in sequence, and freeze-drying the filtered emulsion to obtain the biological enzyme polymer micelle.
The prepared biological enzyme polymer micelle and ceramic particles are soaked in distilled water together, and the mass ratio of the biological enzyme polymer micelle to the ceramic particles to the distilled water is 4:10:100, soaking for 48 hours, stirring once every 1 hour of soaking, finally repeatedly performing suction filtration for 5 times by using a soaking solution, and drying to obtain the core ceramic particles.
Taking 20g of core ceramic particles, adding 200mL of absolute ethyl alcohol and 20mL of pure water, adjusting the pH value to 8 by ammonia water, and stirring for 30min; adding KH-570 (gamma-methacryloxypropyltrimethoxysilane) accounting for 20wt% of the ceramic particles, carrying out ultrasonic treatment for 45min, transferring the mixture into a three-neck flask, stirring the mixture at 25 ℃ for reaction for 5h, taking out the mixture after the reaction is finished, filtering the mixture, washing the solid, and drying the solid to finish the modification.
20g of the obtained modified ceramic particles, 200mL of pure water, carboxymethyl cellulose (1 wt% of pure water), hydroxyethyl cellulose (1 wt% of pure water), and potassium persulfate (0.5% of cellulose derivative)wt percent) and reacting for 5 hours at the constant temperature of 25 ℃; after the reaction is finished, taking out, centrifuging, washing, drying, ball-milling and dispersing to obtain a product A 4 。
Comparative example 1:
the temporary plugging agent B which can be controlled by biological enzyme and is used for the natural gas hydrate drilling fluid is prepared by the comparative example 1 The method comprises the following specific steps:
dissolving esterase and an amphiphilic block copolymer (polyethylene glycol and polycaprolactone are composed of 4: 1mg. Removing ethyl acetate by using a rotary evaporator, preparing a uniform film, and then drying in vacuum until the ethyl acetate is removed; dissolving the film in pure water, wherein the mass percent of the film is 5%, hydrating for 5h at 20 ℃ to form stable emulsion by ultrasound, filtering by using 0.45 mu m and 0.22 mu m films in sequence, and freeze-drying to obtain the esterase polymer micelle.
And (2) soaking the prepared esterase polymer micelle and ceramic particles in distilled water together, wherein the mass ratio of the esterase polymer micelle to the ceramic particles to the distilled water is 1:10:100, soaking for 24 hours, stirring once every 1 hour, repeatedly filtering for 3 times by using a soaking solution, and airing to obtain the core ceramic particles.
Taking 15g of core ceramic particles, adding 150mL of absolute ethyl alcohol and 10mL of pure water, adjusting the pH value to 8 by ammonia water, and stirring for 30min; adding KH-560 (gamma- (2, 3-epoxypropoxy) propyl trimethoxy silane) with the weight percent of ceramic particles, performing ultrasonic treatment for 30min, transferring the mixture into a three-neck flask, stirring the mixture for reaction for 4h at the temperature of 15 ℃, taking out the mixture after the reaction is finished, filtering the mixture after the reaction is finished, taking out the mixture after the reaction is finished, filtering the mixture, washing the solid, drying and finishing the modification.
Taking 20g of the prepared modified ceramic particles, 200mL of pure water, carboxymethyl cellulose (1 wt% of the pure water) and potassium persulfate (0.4 wt% of the cellulose derivative), and reacting at a constant temperature of 20 ℃ for 4 hours; after the reaction is finished, taking out, centrifuging, washing, drying, ball-milling and dispersing to obtain a product B 1 。
Comparative example 2:
the temporary plugging agent B which can be controlled by biological enzyme and is used for the natural gas hydrate drilling fluid is prepared by the comparative example 2 The method comprises the following specific steps:
dissolving esterase and amphiphilic block copolymer (polyethylene glycol and polycaprolactone are composed of 5: 1mg. Removing dichloromethane by using a rotary evaporator, preparing a uniform film, and drying in vacuum until dichloromethane is removed; dissolving the film in phosphate buffer solution, wherein the mass percent of the film is 5%, hydrating for 5h at 20 ℃ to form stable emulsion by ultrasonic, filtering by using 0.45 mu m and 0.22 mu m films, and freeze-drying to obtain the esterase polymer micelle.
And (2) soaking the prepared esterase polymer micelle and ceramic particles in distilled water together, wherein the mass ratio of the esterase polymer micelle to the ceramic particles to the distilled water is 2:10:100, soaking for 36 hours, stirring once every 1 hour, repeatedly filtering for 4 times by using a soaking solution, and airing to obtain the core ceramic particles.
Taking 15g of core ceramic particles, adding 150mL of absolute ethyl alcohol and 10mL of pure water, adjusting the pH value to 8.5 by ammonia water, and stirring for 30min; adding 20wt% of A-171 (vinyl trimethoxy silane) of ceramic particles, carrying out ultrasonic treatment for 30min, transferring the mixture into a three-neck flask, stirring the mixture at 15 ℃ for reaction for 4h, taking out the mixture after the reaction is finished, filtering the mixture, washing the solid, and drying the solid to finish modification.
Taking 20g of the prepared modified ceramic particles, 200mL of pure water, hydroxyethyl cellulose (1 wt% of the pure water), and potassium persulfate (0.4 wt% of the cellulose derivative), and reacting at a constant temperature of 20 ℃ for 4 hours; after the reaction is finished, taking out, centrifuging, washing, drying, ball-milling and dispersing to obtain a product B 2 。
Comparative example 3:
the temporary plugging agent B which can be controlled by biological enzyme and is used for the natural gas hydrate drilling fluid is prepared by the comparative example 3 The method comprises the following specific steps:
dissolving biological enzyme (hemicellulase and esterase in a mass ratio of 1: 1mg. Removing chloroform by using a rotary evaporator, preparing a uniform film, and drying in vacuum until the chloroform is removed completely; dissolving the film in phosphate buffer solution, wherein the mass percent of the film is 5%, hydrating for 5h at 25 ℃ by ultrasonic to form stable emulsion, filtering by using 0.45 mu m and 0.22 mu m films, and freeze-drying to obtain the biological enzyme polymer micelle.
The prepared biological enzyme polymer micelle and ceramic particles are soaked in distilled water together, and the mass ratio of the hemicellulase polymer micelle to the ceramic particles to the distilled water is 3:10:100, soaking for 48 hours, stirring once every 1 hour, repeatedly filtering for 5 times by using a soaking solution, and airing to obtain the core ceramic particles.
Taking 20g of core ceramic particles, adding 200mL of absolute ethyl alcohol and 20mL of pure water, adjusting the pH value to 9 by ammonia water, and stirring for 30min; adding 15wt% of ceramic particles A-172 (vinyl tri (beta-methoxyethoxy) silane), carrying out ultrasonic treatment for 30min, transferring the mixture into a three-neck flask, stirring the mixture at 25 ℃ for reaction for 4h, taking out the mixture after the reaction is finished, filtering the mixture, washing the solid, and drying the solid to finish the modification.
Taking 20g of the prepared modified ceramic particles, 200mL of pure water, hydroxypropyl cellulose (5 wt% of the pure water), and potassium persulfate (0.4 wt% of the cellulose derivative), and reacting at a constant temperature of 25 ℃ for 4 hours; after the reaction is finished, taking out, centrifuging, washing, drying, ball-milling and dispersing to obtain a product B 3 。
Comparative example 4:
the temporary plugging agent B which can be controlled by biological enzyme and is used for the natural gas hydrate drilling fluid is prepared by the comparative example 4 The method comprises the following specific steps:
dissolving biological enzyme (esterase and cellulase in a mass ratio of 1: 1mg. Removing tetrahydrofuran by using a rotary evaporator, preparing a uniform film, and then drying in vacuum until chloroform is removed; and (2) dissolving the film in a phosphate buffer solution, wherein the mass percent of the film is 5%, hydrating for 5h at 25 ℃ to form a stable emulsion by ultrasonic, filtering by using a 0.45 mu m and 0.22 mu m film, and freeze-drying to obtain the biological enzyme polymer micelle.
And (2) soaking the prepared biological enzyme polymer micelle and ceramic particles in distilled water together, wherein the mass ratio of the cellulase to esterase polymer micelle to the ceramic particles to the distilled water is 4:10:100, soaking for 48 hours, stirring once every 1 hour of soaking, finally repeatedly performing suction filtration for 5 times by using a soaking solution, and drying to obtain the core ceramic particles.
Taking 20g of core ceramic particles, adding 200mL of absolute ethyl alcohol and 20mL of pure water, adjusting the pH value to 8 by ammonia water, and stirring for 30min; adding KH-570 (gamma-methacryloxypropyltrimethoxysilane) accounting for 20wt% of the ceramic particles, performing ultrasonic treatment for 45min, transferring the mixture into a three-neck flask, stirring the mixture for reaction for 5h at 25 ℃, taking out the mixture after the reaction is finished, filtering the mixture, washing the solid, and drying the solid to finish the modification.
Taking 20g of the prepared modified ceramic particles, 200mL of pure water, carboxymethyl cellulose (1 wt% of the pure water), hydroxyethyl cellulose (1 wt% of the pure water), and potassium persulfate (0.5 wt% of the cellulose derivative), and reacting at a constant temperature of 25 ℃ for 5 hours; after the reaction is finished, taking out, centrifuging, washing, drying, ball-milling and dispersing to obtain a product B 4 。
And (4) performance testing:
the temporary plugging agent A of the above example 1 1 Example 2 temporary plugging agent A 2 Example 3 temporary plugging agent A 3 Example 4 temporary blocking agent A 4 Comparative example 1 temporary plugging agent B 1 Comparative example 2 temporary plugging agent B 2 Comparative example 3 temporary plugging agent B 3 Comparative example 4 temporary plugging agent B 4 The performance evaluation was performed by the following experimental methods:
1. evaluation of reservoir protection Effect
And evaluating the reservoir protection effect by a method for testing the permeability recovery value and the recovery time. The prepared different temporary plugging agents invade the rock core after respective buffering periods, and rock core flow experiment evaluation is carried out to measure the rock core permeability recovery values at different times, wherein the rock core index is 5.5cm long and 2.5cm in diameter.
The buffer period is the time from the preparation of the temporary plugging agent to the completion of the degradation of the polymer micelle and the cellulose derivative of the shell by the biological enzyme.
The buffer period determination process comprises the following steps: a certain amount of the temporary plugging agent which is just prepared is taken to be put into pure water, the concentration and the activity of the biological enzyme in the water are zero at the initial time, a certain concentration and activity of the biological enzyme can be detected after a period of time, the final time is the time, and the time difference between the two is the buffer period.
During a buffering periodDifferent production processes can be selected according to the time required by transportation and use when actual products are selected. If a temporary blocking agent A is selected 2 A longer buffer period is provided, which is beneficial to long-distance transportation and long-time operation; temporary plugging agent A 4 The method is beneficial to short-time operation and shortens the mining time.
Specific experimental data are shown in table 1.
TABLE 1 Permeability recovery values
Note: -: the result shows that the biological enzyme polymer micelle is not degraded, the buffering time is long, and the detection is not carried out.
As can be seen from the permeability recovery value data in table 1 above, the temporary plugging agent for natural gas hydrate drilling fluid, which is provided in embodiments 1 to 4 and can be controlled by biological enzyme, has good performance, and can initially form a good plugging effect, after a fixed time (buffer period), the biological enzyme degrades a polymer to form a gas and water migration channel, and the permeability recovery value becomes large; on the contrary, the permeability recovery values of comparative examples 1 to 4 were little or no change due to failure to form gas and water migration paths or long gas and water migration paths formed with a large amount of cellulose derivative. Therefore, the time for degrading the polymer can be accurately controlled by the ratio of the biological enzyme to the polymer, and the time for forming the gas and water transport channels can be further controlled.
The biological enzymes in the embodiments 1, 2 and 4 are esterase and cellulase, the biological enzymes in the embodiment 3 are esterase and hemicellulase, the degradation of the polymer micelle and the cellulose derivatives of the outer shell can be realized, the buffer periods are different due to different contents of the biological enzymes, the polymer micelle and the cellulose derivatives, the pore restoration of the ceramic particles can be realized, and the permeability restoration values are good when the ceramic particles are applied.
In comparative examples 1 and 2, the biological enzyme is esterase, and can only degrade polymer micelles and cellulose derivatives, so that the buffer period cannot be determined and the pores of the ceramic particles cannot be recovered; in comparative example 3, the biological enzymes are esterase and hemicellulase, and the cellulose derivative is used in a large amount, compared with example 3, the polymer micelle can be degraded, but the effect of degrading the cellulose derivative is not good due to the large amount of the cellulose derivative; the buffer period is longer, and the permeability recovery effect is poorer. In comparative example 4, the biological enzymes are esterase and cellulase, but the relative content of the biological enzymes is small, the degradation efficiency of the biological enzymes on the polymer micelle is low, and the biological enzymes and the polymer micelle can not realize effective recovery of the pores of the ceramic particles.
2. Synergistic sand control effect evaluation
The method is characterized in that a hydrate exploitation gas-liquid-solid output device (CN 211201913U) based on ultrasonic yield increase and sand control screen blockage reduction is used for evaluating the sand control effect of the temporary plugging agent in cooperation with the 3D-HP metal fiber sand control screen pipe, and the sand control effect is contrastively analyzed through the sand output in the experimental process. Wherein the sand blocking precision of the 3D-HP metal fiber sand control screen pipe is more than or equal to 40 mu m; the diameter of sand grains for experiments is 10-80 mu m, the experiments are carried out in a mode of pumping clear water to carry and discharge the sand grains, and the discharge capacity of the clear water is 100L/h. And (3) placing the temporary plugging agent and the sand control screen pipe into a reactor, and respectively measuring the sand output amount of 1h after the temporary plugging agent and the sand control screen pipe are placed into the reactor, 5d, 10d, 15d and 20 d. The experimental data are shown in Table 2:
TABLE 2 Sand control Effect
As can be seen from the sand production amount of 1 hour in the above table 2, the temporary plugging agent for natural gas hydrate drilling fluid, which is provided in the embodiments 1 to 4 and can be controlled by the bio-enzyme, has a better sand prevention effect in cooperation with the sand control screen pipe compared with the single use of the sand control screen pipe; as the polymer is degraded by the action of biological enzyme to form a water and gas transportation channel, the sand yield is gradually increased, but is still less than the sand yield when only the sand control screen pipe is used at 20 d; on the contrary, the temporary plugging agent for the natural gas hydrate drilling fluid capable of being controlled by the biological enzyme and provided by the comparative examples 1 to 4 has little sand yield change due to the fact that the temporary plugging agent does not contain the cellulase, so that the cellulose derivative polymer can not be degraded, a channel beneficial to transportation of gas and water can not be formed, and the sand yield is not obviously changed. Therefore, the temporary plugging agent can play a role of synergistic sand prevention when being matched with the sand control screen pipe, and the sand control effect is effectively improved.
The biological enzymes in the examples 1, 2 and 4 are esterase and cellulase, and the biological enzymes in the example 3 are esterase and hemicellulase, so that the degradation of polymer micelle and cellulose derivatives of shells can be realized, the pore gaps of ceramic particles are recovered, and the sand gravel with smaller particle size appears, but the effect is better than that of using a sand control screen only.
The cellulose derivatives were not effectively degraded without cellulase in comparative examples 1, 2 and 4. In comparative example 1 and comparative example 2, the biological enzyme is esterase, and can only degrade polymer micelles, but can not degrade cellulose derivatives, so that the pores of the ceramic particles can not be recovered; in comparative example 3, the biological enzymes were esterase and hemicellulase, and the cellulose derivative was used in a larger amount, and compared with example 3, the polymer micelle was degraded, but the cellulose derivative was not well degraded due to the larger amount of the cellulose derivative. In comparative example 4, the biological enzymes are esterase and cellulase, but the relative content of the biological enzymes is less, the degradation efficiency of the polymer micelle is low, and the biological enzymes and the polymer micelle can not realize effective recovery of the pores of the ceramic particles. So that only a very small amount of sand can pass.
It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.
Claims (17)
1. The temporary plugging agent for the natural gas hydrate drilling fluid is characterized by being of a shell-core structure and comprising inner core ceramic particles with porous channels and a polymer shell grafted outside the inner core through a silane coupling agent; the porous channel comprises a biological enzyme polymer micelle;
the components of the polymeric shell include a cellulose derivative;
the biological enzyme polymer micelle is formed by coating biological enzyme in a hydrophobic core of an amphiphilic block copolymer, and the amphiphilic block copolymer comprises a hydrophilic block A and a hydrophobic block B;
the hydrophilic block A is selected from polyethylene glycol, polyethylene glycol monomethyl ether, hyaluronic acid or polyacrylic acid dextran;
the hydrophobic block B is selected from polyglycolide, polylactide, polycaprolactone, polyglycolide, polycarbonate, polyesteramide or polyether ester;
the mass ratio of the hydrophilic block A to the hydrophobic block B is 4 to 6;
the mass ratio of the biological enzyme to the amphiphilic block copolymer is 1;
the biological enzyme is selected from cellulase and esterase, and can realize the degradation of polymer micelle and shell cellulose derivative.
2. The temporary plugging agent for natural gas hydrate drilling fluid according to claim 1, wherein the cellulose derivative is one or a combination of two or more selected from carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose.
3. The temporary plugging agent for natural gas hydrate drilling fluid according to claim 1, wherein the silane coupling agent is one or a combination of more than two of gamma-aminopropyltriethoxysilane, gamma- (2, 3-epoxypropoxy) propyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane and vinyltris (beta-methoxyethoxy) silane.
4. The temporary plugging agent for the natural gas hydrate drilling fluid, according to claim 1, wherein the average particle size of the bio-enzyme polymer micelle is 50 nm-220 nm.
5. The temporary plugging agent for the natural gas hydrate drilling fluid as claimed in claim 1, wherein the average particle size of the ceramic particles is 40-60 μm, and the average pore diameter is 3-5 μm.
6. A preparation method of the temporary plugging agent for the natural gas hydrate drilling fluid, which is described in any one of claims 1 to 5, is characterized by comprising the following steps:
preparing the biological enzyme polymer micelle by adopting a thin film hydration method;
soaking the biological enzyme polymer micelle and the ceramic particles in distilled water together to enable the biological enzyme polymer micelle to enter porous channels of the ceramic particles, and airing after soaking to obtain the core ceramic particles;
modifying the core ceramic particles with a silane coupling agent;
and carrying out polymerization reaction on the modified core ceramic particles and cellulose derivatives under the action of an initiator to complete grafting so as to form the polymer shell, thus obtaining the temporary plugging agent.
7. The method according to claim 6, wherein the thin film hydration method specifically comprises:
dissolving a biological enzyme and an amphiphilic block copolymer in an organic solvent;
removing the organic solvent by using a rotary evaporator, preparing a uniform film, and drying in vacuum until the organic solvent is removed;
dissolving the film in pure water or phosphate buffer solution, hydrating for 2 to 10 hours, performing ultrasonic treatment to form stable emulsion, filtering by using 0.45 and 0.22 mu m films in sequence, and performing freeze drying to obtain the biological enzyme polymer micelle.
8. The method according to claim 7, wherein the organic solvent is one or a combination of two or more selected from the group consisting of ethyl acetate, dichloromethane, chloroform, acetonitrile, and tetrahydrofuran.
9. The preparation method according to claim 7, wherein the dosage ratio of the organic solvent to the biological enzyme is (1.0 to 2.0) mL:1mg.
10. The method according to claim 7, wherein the film is dissolved in pure water or phosphate buffer solution, and the mass percentage of the film is 0.1% -10%.
11. The method of claim 7, wherein the hydration temperature is 15 ℃ to 35 ℃.
12. The preparation method according to claim 6, wherein the mass ratio of the bio-enzyme polymer micelle to the ceramic particles to the distilled water is (1 to 5): (10 to 50): (100 to 500); the soaking time is 24-48 h, the stirring is carried out once every 1h of soaking, and finally the soaking liquid is repeatedly filtered and filtered for 3-5 times to complete the soaking.
13. The method according to claim 6, wherein the step of modifying the inner ceramic particle with a silane coupling agent specifically comprises:
mixing 15 to 20 parts by weight of the inner core ceramic particles, 150 to 200 parts by weight of absolute ethyl alcohol and 10 to 20 parts by weight of pure water, adjusting the pH value to 7.5 to 9 by ammonia water, and stirring for 30 to 60min;
adding 15-20 wt% of silane coupling agent into the ceramic particles, performing ultrasonic treatment for 30-60 min, reacting for 4-6 h at 15-35 ℃, filtering after the reaction is finished, washing the solid, and drying.
14. The method for preparing according to claim 6, wherein the step of forming the polymer housing comprises in particular:
mixing the modified core ceramic particles, cellulose derivatives, an initiator and pure water, and reacting for 4-6 h at 15-35 ℃; and after the reaction is finished, centrifuging, washing the solid, drying, and performing ball milling dispersion to obtain the temporary plugging agent.
15. The method of claim 14, wherein the cellulose derivative is present in the system at a concentration of 1wt% to 3wt% in the step of forming the polymer shell.
16. The method of claim 14, wherein the initiator is used in an amount of 0.4wt% to 0.6wt% of the cellulose derivative.
17. The method according to claim 14, wherein the initiator is potassium persulfate.
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