阅读说明：本技术 一种水基钻井液用环保型抗超高温降滤失剂的制备方法 (Preparation method of environment-friendly ultra-high temperature resistant filtrate reducer for water-based drilling fluid ) 是由 黄贤斌 孙金声 吕开河 金家锋 刘敬平 白英睿 王金堂 于 2020-08-11 设计创作，主要内容包括：本发明提供了一种水基钻井液用环保型抗超高温降滤失剂的制备方法,首先将纳米锂皂石和硅烷偶联剂反应,得到纳米交联剂；之后在纳米交联剂和引发剂的存在下,使用反相乳液聚合法,通过酰胺类单体、抗高温单体、阳离子单体、多烯单体聚合反应制得环保型抗超高温降滤失剂。本发明制备的降滤失剂能够抗高温,并且具有优异的降滤失效果和良好的环保性能。本发明的降滤失剂不仅适用于深层超深层油气钻探,而且适用于地热井、环境敏感区域的钻探。(The invention provides a preparation method of an environment-friendly ultra-high temperature resistant filtrate reducer for water-based drilling fluid, which comprises the steps of firstly reacting nano hectorite with a silane coupling agent to obtain a nano cross-linking agent; and then in the presence of a nano cross-linking agent and an initiator, preparing the environment-friendly ultrahigh-temperature resistant filtrate reducer by using an inverse emulsion polymerization method and carrying out polymerization reaction on an amide monomer, a high-temperature resistant monomer, a cationic monomer and a polyene monomer. The fluid loss agent prepared by the invention can resist high temperature, and has excellent fluid loss effect and good environmental protection performance. The fluid loss additive is not only suitable for drilling deep ultra-deep oil and gas, but also suitable for drilling geothermal wells and environment sensitive areas.)

1. A preparation method of an environment-friendly ultra-high temperature resistant filtrate reducer for water-based drilling fluid comprises the following steps:

(1) sequentially adding the nano hectorite and the silane coupling agent into a solvent, and reacting under the stirring condition; after the reaction is finished, filtering, washing, drying and grinding to obtain the nano cross-linking agent;

(2) dissolving Span80 in white oil, and then adding the nano cross-linking agent prepared in the step (1) to obtain an oil phase;

(3) sequentially adding an amide monomer, a high-temperature-resistant monomer, a cationic monomer and a polyene monomer into distilled water, adjusting the pH of the system to 6-9, and adding Tween80 to obtain a water phase;

(4) mixing the oil phase and the water phase, and emulsifying to obtain emulsion; adding an initiator aqueous solution into the emulsion under the nitrogen atmosphere, and reacting under the stirring condition; and after the reaction is finished, adding a precipitator into the reaction liquid, and filtering, washing and drying to obtain the ultrahigh-temperature-resistant filtrate reducer for the water-based drilling fluid.

2. The preparation method of the environment-friendly ultrahigh temperature resistant fluid loss additive for the water-based drilling fluid according to claim 1, wherein the silane coupling agent in the step (1) is one or two of gamma-methacryloxypropyltrimethoxysilane (KH570), vinyltrimethoxysilane (KH-171) and vinyltris (b-methoxyethoxy) silane (KH-172);

the nano hectorite is a flaky nano particle with the diameter of 15-25nm and the thickness of 1-2 nm;

the mass ratio of the nano hectorite to the silane coupling agent is 2-10: 1, preferably 4 to 6: 1.

3. the preparation method of the environment-friendly ultrahigh-temperature-resistant fluid loss additive for the water-based drilling fluid according to claim 1, wherein the solvent in the step (1) is acetone, toluene, xylene, butanone or petroleum ether; the ratio of the mass of the nano hectorite to the volume of the solvent is 0.1-0.2g:1 mL.

4. The preparation method of the environment-friendly ultra-high temperature resistant fluid loss additive for the water-based drilling fluid as claimed in claim 1, wherein the stirring rate in the step (1) is 200-400r/min, preferably 300 r/min; the reaction temperature is 60-80 ℃, and the reaction time is 4-7 h; the washing is carried out by using ethanol; the grinding is to grind the product into powder with the size of less than 200 meshes.

5. The preparation method of the environment-friendly ultrahigh-temperature-resistant fluid loss additive for the water-based drilling fluid according to claim 1, wherein the ratio of the mass of Span80 to the volume of white oil in the step (2) is 0.02-0.06g:1 mL; the mass ratio of the Span80 to the nano cross-linking agent is 0.8-3.2:1, and preferably 1-3: 1.

6. The preparation method of the environment-friendly ultrahigh-temperature-resistant fluid loss additive for the water-based drilling fluid according to claim 1, wherein the amide monomer in the step (3) is acrylamide, methacrylamide, N-hydroxyethyl acrylamide or N-isopropyl acrylamide; the mass ratio of the amide monomer to the volume of the distilled water is 0.15-0.2 g:1 mL;

the high-temperature resistant monomer is one or the combination of more than two of 2-acrylamide-2-methyl propane sulfonic Acid (AMPS), sodium vinyl sulfonate, sodium styrene sulfonate and sodium allyl sulfonate; the mass ratio of the high-temperature resistant monomer to the volume of the distilled water is 0.075-0.125 g:1 mL;

the cationic monomer is one or the combination of two of dimethyl diallyl ammonium chloride (DMDAAC), methacryloyloxyethyl trimethyl ammonium chloride (DMC) and acryloyloxyethyl trimethyl ammonium chloride (DAC); the mass ratio of the cationic monomer to the volume of the distilled water is 0.01-0.025 g:1 mL;

the polyene monomer is divinylbenzene, triallyl isocyanurate or diallyl diphenyl silane; the mass ratio of the polyene monomer to the volume of the distilled water is 0.5-2.5 g: 1L of the compound.

7. The preparation method of the environment-friendly ultra-high temperature resistant fluid loss additive for the water-based drilling fluid according to claim 1, wherein the pH value of the system is adjusted by adopting a NaOH solution with the mass fraction of 30% in the step (3);

the mass ratio of the Tween80 to the volume of the distilled water is 0.005-0.02 g:1 mL.

8. The preparation method of the environment-friendly ultrahigh-temperature-resistant fluid loss additive for the water-based drilling fluid according to claim 1, wherein the volume ratio of the white oil in the oil phase to the distilled water in the water phase in the step (4) is 3: 1.5-2;

the emulsification is carried out for 5min by using a shearing emulsifying machine under the condition of 2000 r/min;

the initiator is one or the combination of more than two of ammonium persulfate, potassium persulfate, dibenzoyl peroxide and tert-butyl hydroperoxide; the addition amount of the initiator is 0.1-1% of the total mass of the amide monomer, the high temperature resistant monomer, the cationic monomer and the polyene monomer; the mass fraction of the initiator aqueous solution is 10%.

9. The preparation method of the environment-friendly ultra-high temperature resistant fluid loss additive for the water-based drilling fluid as claimed in claim 1, wherein the stirring rate in the step (4) is 200-400r/min, preferably 300 r/min; the reaction temperature is 60-80 ℃, and the reaction time is 4-6 h.

10. The preparation method of the environment-friendly ultrahigh-temperature resistant filtrate reducer for the water-based drilling fluid according to claim 1, wherein the precipitator in the step (4) is acetone; the washing is carried out by using ethanol; the drying is carried out for 4-6h at 90-110 ℃.

Technical Field

The invention relates to a preparation method of an environment-friendly ultra-high temperature resistant filtrate reducer for water-based drilling fluid, belonging to the field of oilfield chemistry of petroleum industry.

Background

The high-temperature-resistant water-based drilling fluid is a key technology for high-temperature formation drilling, and plays an irreplaceable important role in exploration and development of deep ultra-deep oil and gas resources and geothermal resources and scientific drilling on continents. In the field of oil and gas resources, with the development of exploration and development to deep ultra-deep layers, the formation temperature is higher and higher, and the temperature of a deep reservoir can reach 200-260 ℃ (in drilling engineering, the temperature higher than 200 ℃ is considered as ultra-high temperature). In high-temperature stratum drilling engineering, the high-temperature stability of the drilling fluid faces huge challenges, the high-temperature stability of the drilling fluid is poor, complex conditions such as borehole instability and drill sticking are easily caused, and the safety, economy and efficiency of the drilling engineering are seriously influenced.

The filtrate reducer is a core treating agent of high-temperature resistant drilling fluid, and the main research and development directions of the filtrate reducer with high-temperature resistance at present are synthetic polymer high-temperature resistant filtrate reducers. Under the action of high temperature, molecular chains of high molecular compounds are broken, the degradation form of the high molecular compounds in a drilling fluid water environment is mainly high-temperature hydrolysis, and factors such as temperature, shearing action, pH and the like can intensify the hydrolysis.

The polymer-type high-temperature-resistant fluid loss additive synthesized at present is mainly a copolymer of alkenyl monomers, and the monomers comprise acrylic acid, acrylamide, styrene, 2-acrylamide-2-methylpropanesulfonic Acid (AMPS), sulfonated Styrene Sodium Salt (SSS), N-vinyl pyrrolidone, dienePropyl dimethyl ammonium chloride, acrylates, and the like. The molecular structure of the polymer determines the performance of the polymer, the reasonable molecular structure is the basis of the polymer for resisting a certain high temperature, and the current principle for optimizing the molecular structure of the polymer mainly comprises the following three points: (1) the main chain structure with strong stability is used, so that the thermal stability of the main chain of the polymer molecule is improved, for example, the thermal stability of the polymer can be obviously improved by using the carbon-carbon main chain; (2) large side groups and rigid side groups (such as long-chain alkyl, benzene rings and the like) are introduced into a molecular structure, and due to the steric effect of the groups, the molecular motion resistance is large, so that the rigidity of a main chain can be enhanced; (3) in the water-based drilling fluid, hydrolysis is the main mode of polymer degradation, the hydrolysis speed is accelerated at high temperature, and hydrolysis-resistant groups (-SO) are introduced into a molecular structure₃-COOH, etc.) is also one of the means to improve the high temperature stability of the polymer. But the research of improving the high-temperature stability performance of the polymer by optimizing the molecular structure of the polymer has made great progress and is difficult to make further breakthrough.

The temperature resistance of the polymer can be improved by forming the polymer into a certain network structure through covalent bond crosslinking, but the crosslinking degree is small as a water-soluble filtrate reducer. U.S. Pat. No. 5,5789349 proposes a controlled crosslinking polymer technique, in which N, N-methylenebisacrylamide is used as a crosslinking agent to moderately crosslink AM and AMPS copolymers, and the formed polymer crosslinked structure is stable at a temperature of 204 ℃. Chinese patent document CN104119845A provides a filtrate reducer for oil field drilling fluid and a preparation method thereof, the filtrate reducer is prepared by taking lignin, acrylamide and 2-acrylamide-2-methylpropanesulfonic acid as synthetic monomers, graft copolymerizing the lignin, the acrylamide and the 2-acrylamide-2-methylpropanesulfonic acid under respective initiation of potassium persulfate, ammonium ferrous sulfate hexahydrate and hydrogen peroxide, and adding a cross-linking agent N, N-methylene bisacrylamide to enhance the stability of the filtrate reducer under high temperature conditions, so as to synthesize a novel high temperature resistant filtrate reducer. However, in the drilling fluid environment, amide bonds of N, N-methylene bisacrylamide are easy to hydrolyze, so that the crosslinking effect is poor.

Currently, the existing polymer fluid loss additives have the following disadvantages: (1) the high temperature resistance is insufficient, the solution is degraded and loses efficacy under the high temperature condition, and the drilling requirement of deep stratum can not be met; (2) the environment-friendly performance is poor, and the drilling requirement of an environment sensitive area can not be met.

Therefore, the development of a novel cross-linking agent for slightly cross-linking the alkenyl monomer polymer to obtain the filtration loss reducer which is resistant to ultrahigh temperature, non-toxic and easily biodegradable has important significance.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a preparation method of an environment-friendly ultrahigh temperature resistant filtrate reducer for water-based drilling fluid. The invention polymerizes high temperature resistant alkenyl monomers, and lightly cross-links covalent bonds of the monomers by using a nano cross-linking agent with high temperature resistant structural characteristics to prepare the water-soluble high temperature resistant polymer filtrate reducer with a certain network structure.

The technical scheme of the invention is as follows:

a preparation method of an environment-friendly ultra-high temperature resistant filtrate reducer for water-based drilling fluid comprises the following steps:

(1) sequentially adding the nano hectorite and the silane coupling agent into a solvent, and reacting under the stirring condition; after the reaction is finished, filtering, washing, drying and grinding to obtain the nano cross-linking agent;

(2) dissolving Span80 in white oil, and then adding the nano cross-linking agent prepared in the step (1) to obtain an oil phase;

(3) sequentially adding an amide monomer, a high-temperature-resistant monomer, a cationic monomer and a polyene monomer into distilled water, adjusting the pH of the system to 6-9, and adding Tween80 to obtain a water phase;

(4) mixing the oil phase and the water phase, and emulsifying to obtain emulsion; adding an initiator aqueous solution into the emulsion under the nitrogen atmosphere, and reacting under the stirring condition; and after the reaction is finished, adding a precipitator into the reaction liquid, and filtering, washing and drying to obtain the ultrahigh-temperature-resistant filtrate reducer for the water-based drilling fluid.

According to the present invention, preferably, the silane coupling agent in step (1) is one or two of gamma-methacryloxypropyltrimethoxysilane (KH570), vinyltrimethoxysilane (KH-171) and vinyltris (b-methoxyethoxy) silane (KH-172).

According to the present invention, preferably, the nano hectorite in step (1) is a plate-like nano particle with a diameter of 15-25nm and a thickness of 1-2 nm; the mass ratio of the nano hectorite to the silane coupling agent is 2-10: 1, more preferably 4 to 6: 1.

according to the present invention, it is preferable that the solvent in step (1) is acetone, toluene, xylene, methyl ethyl ketone or petroleum ether.

According to the invention, the ratio of the mass of the nano hectorite to the volume of the solvent in the step (1) is preferably 0.1-0.2g:1 mL.

According to the present invention, preferably, the stirring rate in step (1) is 200-400r/min, and more preferably 300 r/min; the reaction temperature is 60-80 ℃, and the reaction time is 4-7 h.

According to the present invention, it is preferable that the washing in the step (1) is washing with ethanol; the grinding is to grind the product into powder with the size of less than 200 meshes.

According to the invention, the ratio of the mass of the Span80 to the volume of the white oil in the step (2) is preferably 0.02-0.06g:1 mL; the mass ratio of the Span80 to the nano cross-linking agent is 0.8-3.2:1, and the preferable ratio is 1-3: 1.

According to the present invention, it is preferable that the amide-based monomer in step (3) is acrylamide, methacrylamide, N-hydroxyethyl acrylamide or N-isopropyl acrylamide; the mass ratio of the amide monomer to the volume of the distilled water is 0.15-0.2 g:1 mL.

According to the invention, preferably, the high temperature resistant monomer in the step (3) is one or a combination of more than two of 2-acrylamido-2-methylpropanesulfonic Acid (AMPS), sodium vinylsulfonate, sodium styrene sulfonate and sodium allylsulfonate; the mass ratio of the high-temperature resistant monomer to the volume of the distilled water is 0.075-0.125 g:1 mL.

According to the present invention, preferably, the cationic monomer in step (3) is one or a combination of two of dimethyldiallylammonium chloride (DMDAAC), methacryloyloxyethyltrimethylammonium chloride (DMC) and acryloyloxyethyltrimethylammonium chloride (DAC); the mass ratio of the cationic monomer to the volume of the distilled water is 0.01-0.025 g:1 mL.

According to the present invention, it is preferred that the polyene monomer described in step (3) is divinylbenzene, triallylisocyanurate or diallyldiphenylsilane; the mass ratio of the polyene monomer to the volume of the distilled water is 0.5-2.5 g: 1L of the compound.

According to the invention, preferably, a NaOH solution with the mass fraction of 30% is used for adjusting the pH of the system in the step (3).

According to the present invention, it is preferable that the ratio of the mass of Tween80 to the volume of distilled water in the step (3) is 0.005 to 0.02 g:1 mL.

According to the present invention, it is preferred that the volume ratio of the white oil in the oil phase to the distilled water in the water phase in step (4) is 3: 1.5-2.

According to the invention, the emulsification in the step (4) is preferably carried out for 5min at 2000r/min by using a shearing emulsifying machine.

According to the invention, preferably, the initiator in the step (4) is one or a combination of more than two of ammonium persulfate, potassium persulfate, dibenzoyl peroxide and tert-butyl hydroperoxide; the addition amount of the initiator is 0.1-1% of the total mass of the amide monomer, the high temperature resistant monomer, the cationic monomer and the polyene monomer; the mass fraction of the initiator aqueous solution is 10%.

According to the present invention, preferably, the stirring rate in the step (4) is 200-400r/min, and more preferably 300 r/min; the reaction temperature is 60-80 ℃, and the reaction time is 4-6 h.

According to the invention, preferably, the precipitant in step (4) is acetone, and the amount of the precipitant is determined according to the requirement, and the stirring is continuously added until the precipitate is completely separated out.

According to the present invention, it is preferable that the washing in the step (4) is washing with ethanol; the drying is carried out for 4-6h at 90-110 ℃.

The invention has the following technical characteristics and beneficial effects:

1. the filtrate reducer prepared by the invention can resist high temperature. The invention takes nano hectorite and silane coupling agent as raw materials to prepare the nano cross-linking agent, the silane coupling agent in the nano cross-linking agent is positioned on the surface of the nano hectorite and can be cross-linked with other monomers, the addition of the nano cross-linking agent increases the temperature resistance of the polymer, and the main reasons are divided into two aspects: firstly, the nano cross-linking agent slightly cross-links the polymer, so that the free movement of molecular chains is limited, and the temperature resistance and hydrolysis resistance of the polymer are improved; secondly, the temperature resistance of the nano cross-linking agent particles is stronger, and the addition of the nano cross-linking agent particles is beneficial to improving the temperature resistance of the polymer. Meanwhile, the high-temperature resistant monomer in the filtrate reducer is introduced, so that the temperature resistance of the filtrate reducer can be improved, and the filtrate reducer can resist the high temperature of 220 ℃; the polyene monomer plays a role in crosslinking in the reaction and is matched with the nano crosslinking agent, so that the temperature resistance of the filtrate reducer is improved.

2. The fluid loss agent prepared by the invention has excellent fluid loss effect. The addition of the cationic monomer enables the synthesized polymer filtrate reducer to have positive charge groups in an aqueous solution, and can generate an adsorption effect with the surface of negatively charged clay; the addition of the high-temperature resistant monomer introduces anionic groups into the filtrate reducer, and as the end face of clay particles is positively charged, the anionic groups contained in the filtrate reducer also have certain adsorption effect on the surface of clay minerals, so that the flocculation and enlargement of the clay particles are prevented, and the effect of stabilizing the colloidal particles is achieved. In addition, the addition of the nano cross-linking agent can play a role in blocking to a certain extent, so that the effect of reducing the filtration loss is achieved.

3. The filtrate reducer prepared by the invention has good environmental protection performance, and experiments prove that the EC of the filtrate reducer is₅₀＞30000ppm，BOD₅/COD_CrMore than 25%, indicating that it is non-toxic and easily biodegradable. The fluid loss additive is not only suitable for drilling deep ultra-deep oil and gas, but also suitable for drilling geothermal wells and environment sensitive areas.

Detailed Description

The present invention is further illustrated by, but not limited to, the following examples.