阅读说明：本技术 一种用于钻井液的纳米胶乳强封堵剂及其制备方法 (Nano latex strong plugging agent for drilling fluid and preparation method thereof ) 是由 曹何山 卢新玉 卢长征 沈勤长 于 2019-10-11 设计创作，主要内容包括：本发明公开了一种用于钻井液的纳米胶乳强封堵剂及其制备方法,其包括以下重量份的原料：乙烯基液10-60份；丙烯基液5-25份；甲基丙烯酸磺酸钠1-19份；副乳化剂0.1-10份；引发剂0.01-2份；水：10-60份。一种纳米胶乳强封堵剂的制备方法为：S1预乳液的制备S1-1制备水相；S1-2制备油相；S1-3将油滴加到水相中,混合均匀,得到预乳液；S2于预乳液中加引发剂,搅拌后备用；S3将步骤S2中制备得到溶液加入水搅拌,得到纳米胶乳强封堵剂。本发明的纳米胶乳强封堵剂可用于钻井液用封堵剂,具有高效快速封堵页岩中微纳米缝隙的优点。(The invention discloses a nano latex strong plugging agent for drilling fluid and a preparation method thereof, wherein the nano latex strong plugging agent comprises the following raw materials in parts by weight: 10-60 parts of vinyl liquid; 5-25 parts of propylene-based liquid; 1-19 parts of sodium methacrylate sulfonate; 0.1-10 parts of a secondary emulsifier; 0.01-2 parts of an initiator; water: 10-60 parts. The preparation method of the nano latex strong plugging agent comprises the following steps: preparation of S1 Pre-emulsion S1-1 preparation of the aqueous phase; s1-2, preparing an oil phase; s1-3, adding oil drops into the water phase, and uniformly mixing to obtain a pre-emulsion; s2, adding an initiator into the pre-emulsion, and stirring for later use; s3, adding water into the solution prepared in the step S2, and stirring to obtain the nano latex strong plugging agent. The nano latex strong plugging agent can be used as a plugging agent for drilling fluid, and has the advantage of efficiently and quickly plugging micro-nano gaps in shale.)

1. The nano latex strong plugging agent for the drilling fluid is characterized by comprising the following raw materials in parts by weight:

10-60 parts of vinyl liquid;

5-25 parts of propylene-based liquid;

1-19 parts of sodium methacrylate sulfonate;

0.1-10 parts of a secondary emulsifier;

0.01-2 parts of an initiator;

water: 10-60 parts.

2. The nano latex strong plugging agent for drilling fluid is characterized by comprising the following raw materials in parts by weight:

25-45 parts of vinyl liquid;

12-18 parts of propylene-based liquid;

7.5-12.5 parts of sodium methacrylate;

3-7 parts of a secondary emulsifier;

0.5-1.5 parts of initiator;

water: 25-45 parts.

3. The nano latex strong plugging agent for drilling fluid, according to claim 1, is characterized in that: the vinyl liquid is a mixture of styrene and vinyl propionate; the propylene-based fluid is a mixture of acrylic acid, vinyl acrylate, and cyclohexyl methacrylate.

4. The nano latex strong plugging agent for drilling fluid, according to claim 1, is characterized in that: the mass ratio of the styrene to the vinyl propionate is 12: 5-9; the mass ratio of the acrylic acid to the vinyl acrylate to the cyclohexyl methacrylate is 2:4: 1-2.

5. The nano latex strong plugging agent for drilling fluid, according to claim 1, is characterized in that: the secondary emulsifier is selected from one of fatty alcohol polyoxyethylene ether sodium sulfate, octyl phenol polyoxyethylene (10) ether, octyl phenol polyoxyethylene (8) ether and octyl phenol polyoxyethylene (6) ether.

6. The nano latex strong plugging agent for drilling fluid, according to claim 1, is characterized in that: the initiator is selected from one of potassium persulfate, sodium persulfate, ammonium persulfate or benzoyl peroxide.

7. The preparation method of the nano latex strong plugging agent for the drilling fluid, which is described in any one of claims 1 to 6, is characterized by comprising the following steps:

preparation of S1 Pre-emulsion

S1-1, adding the main emulsifier into water, and stirring to prepare a water phase;

s1-2, mixing the secondary emulsifier, the vinyl liquid and the propylene liquid, and then uniformly stirring to prepare an oil phase;

s1-3, adding oil drops into the water phase under the stirring condition, and uniformly mixing to obtain a pre-emulsion;

s2, adding an initiator into the prepared pre-emulsion, and uniformly stirring for later use;

s3, adding water into the solution prepared in the step S2, and stirring at the temperature of 80-100 ℃ for 50-90min to obtain the nano latex strong plugging agent.

Technical Field

The invention relates to the technical field of latex blocking agents, in particular to a nano latex strong blocking agent for drilling fluid and a preparation method thereof.

Background

The loss of drilling fluid and the formation of filter cake the loss of drilling fluid is inevitable during drilling and filter cake can be formed by the loss of fluid to protect the well wall. However, the drilling fluid has too large filtration loss, which easily causes the shale to expand and collapse, resulting in the instability of the well wall. In addition, the filter cake thickens while the filtration loss is increased, so that the well diameter is reduced, a large torque is caused to a rotating drilling tool, swabbing and pressure fluctuation are caused when the drilling tool is tripped out, and differential pressure drill sticking is easily caused. Therefore, proper control of fluid loss is one of the important properties of a drilling fluid.

Meanwhile, in the process of drilling shale gas, because shale formations are usually very compact and have very low porosity, the size of shale pores is in the range of several nanometers to hundreds of nanometers, and the particle size of a common plugging agent is large, the plugging agent cannot plug the pores or has a poor plugging effect. Based on the special properties of small-size effect, surface effect, selective adsorption and the like of the nano material, many scholars at home and abroad begin to apply various nano materials to shale gas water-based drilling fluid to improve the performance of the drilling fluid. Nanolatexes generally refer to submicron colloidal systems of synthetic polymers or natural macromolecules with particle sizes in the range of a few nanometers to 1 micron. The nano latex has stronger well wall stability and better lubricating and oil layer protecting performances. The water-based drilling fluid added with the nano material has the effects of improving the inhibition of hydration expansion of shale, improving the quality of mud cakes and the rheological property of the drilling fluid, improving the lubricity of the drilling fluid, reducing the abrasion of a drill column and the like.

The invention patent with the application number of 2018102643174 discloses an acrylate emulsion with a core-shell structure and a preparation method and application thereof. The emulsion is obtained by polymerizing raw materials comprising the following components: polymerized monomer, nano silicon dioxide, surfactant, polyvinyl alcohol, initiator and water; wherein the polymerized monomer forms a shell layer of the emulsion particle and consists of a hard monomer and a hydrophilic monomer, and the hard monomer is more than two selected from styrene, methyl methacrylate and acrylonitrile; the hydrophilic monomer is at least one of acrylic acid, hydroxyethyl methacrylate and hydroxyethyl acrylate; the nano-silica forms a core layer of the latex particles. The emulsion provided by the invention can be used as a plugging agent and added into water-based drilling fluid to realize effective plugging of core pores under the conditions of high temperature and high pressure.

However, the plugging speed of the invention is not very fast in the plugging process of the shale layer, so that the whole plugging operation is low in efficiency.

Disclosure of Invention

Aiming at the defects in the prior art, the first object of the invention is to provide a nano latex strong plugging agent for drilling fluid, which has the advantages of quickly plugging shale pores and reducing the fluid loss of the drilling fluid.

The second purpose of the invention is to provide a preparation method of the nano latex strong plugging agent for the drilling fluid.

In order to achieve the first object, the invention provides the following technical scheme: a nano latex strong plugging agent for drilling fluid comprises the following raw materials in parts by weight:

10-60 parts of vinyl liquid;

5-25 parts of propylene-based liquid;

1-19 parts of sodium methacrylate sulfonate;

0.1-10 parts of a secondary emulsifier;

0.01-2 parts of an initiator;

water: 10-60 parts.

By adopting the technical scheme, the vinyl monomer and the allyl ester have poor emulsifying property and can be emulsified only under the action of the emulsifier; the sodium methacrylate sulfonate has good emulsifying property and has the characteristics of salt resistance and high temperature resistance; vinyl monomers and propenyl ester firstly form stable oil-in-water (oil/water) emulsion under the action of an emulsifier and a secondary emulsifier, and then small molecular monomers undergo polymerization reaction under the action of an initiator to finally form colloidal nano latex. The prepared nano latex contains more nano particles, and can better enter micro-nano pores of shale when being applied to water-based drilling fluid, so that the pores of the shale are better blocked; meanwhile, the nano latex strong plugging agent is obtained by emulsifying and polymerizing vinyl liquid and propylene liquid, can form a layer of compact membrane structure on the surface of a well wall after being used in water-based drilling fluid, has a strong waterproof function, prevents further filtration of the drilling fluid, and can achieve a good plugging effect and further reduce the filtration in the drilling process by combining the two points.

Further, the nano latex strong plugging agent for the drilling fluid comprises the following raw materials in parts by weight:

25-45 parts of vinyl liquid;

12-18 parts of propylene-based liquid;

7.5-12.5 parts of a main emulsifier;

3-7 parts of a secondary emulsifier;

0.5-1.5 parts of initiator;

water: 25-45 parts.

By adopting the technical scheme, the raw material proportioning range for preparing the nano latex strong plugging agent is further optimized, so that the nano latex strong plugging agent prepared in the proportioning range can plug shale.

Further, the vinyl liquid is a mixture of styrene and vinyl propionate; the propylene-based fluid is a mixture of acrylic acid, vinyl acrylate, and cyclohexyl methacrylate.

Further, the mass ratio of the styrene to the vinyl propionate is 12: 5-9; the mass ratio of the acrylic acid to the vinyl acrylate to the cyclohexyl methacrylate is 2:4: 1-2.

By adopting the technical scheme, styrene and acrylic acid are polymerized under the action of an initiator, meanwhile, styrene, acrylic acid and vinyl acrylate are copolymerized, vinyl propionate and acrylic acid are copolymerized, cyclohexyl methacrylate and styrene are copolymerized to generate polystyrene, the polystyrene has the characteristics of high transparency, high rigidity, good rigidity, chemical corrosion resistance, high glass transition temperature and the like, but as the polystyrene is brittle, in order to overcome the defect, part of vinyl propionate is added into the styrene, and the vinyl propionate and the styrene are polymerized under the action of an emulsifier and the initiator, so that the obtained polymer is acid-resistant and alkali-resistant and has good water resistance, and when the product is used as a plugging agent of a water-based drilling fluid, the product has a better adhesion plugging effect on shale gaps and has higher water resistance.

Further, the secondary emulsifier is selected from one of fatty alcohol polyoxyethylene ether sodium sulfate, octyl phenol polyoxyethylene (10) ether, octyl phenol polyoxyethylene (8) ether and octyl phenol polyoxyethylene (6) ether.

By adopting the technical scheme, the auxiliary emulsifier is added, the auxiliary emulsifier and the emulsifier are matched with each other, each polymerized monomer is better dispersed into tiny monomer globules to form solubilizing micelles, and the emulsifier is adsorbed on the surfaces of the monomer globules and emulsion particles to form stable polymer emulsion.

Further, the initiator is selected from one of potassium persulfate, sodium persulfate or ammonium persulfate.

By adopting the technical scheme, the initiator is used to promote the monomer in the emulsion state to polymerize, so that the stable nano emulsion is formed.

In order to achieve the second object, the invention provides the following technical scheme:

a preparation method of a nano latex strong plugging agent for drilling fluid is characterized by comprising the following steps:

preparation of S1 Pre-emulsion

S1-1, adding the main emulsifier into water, and stirring to prepare a water phase;

s1-2, mixing the secondary emulsifier, the vinyl liquid and the propylene liquid, and then uniformly stirring to prepare an oil phase;

s1-3, adding oil drops into the water phase under the stirring condition, and uniformly mixing to obtain a pre-emulsion;

s2, adding an initiator into the prepared pre-emulsion, and uniformly stirring for later use;

s3, adding water into the solution prepared in the step S2, and stirring at the temperature of 80-100 ℃ for 50-90min to obtain the nano latex strong plugging agent.

By adopting the technical scheme, the nano latex with a stable system is prepared, nano particles in the nano latex are more, the filtration loss rate of shale is lower, and the shear strength of the shale after the nano latex is applied to the shale is higher.

In conclusion, the invention has the following beneficial effects:

firstly, because the mixture of styrene and vinyl propionate is used as the vinyl liquid, and acrylic acid, vinyl propionate and cyclohexyl methacrylate are used as the propylene-based liquid, all monomers are polymerized, the nano-scale particle occupation ratio in the particles of the prepared nano-latex emulsion is high, and the efficient plugging of the micro-nano gaps of the shale is realized.

Secondly, the invention optimizes the dosage ratio of styrene to vinyl propionate in the vinyl liquid and the dosage ratio of acrylic acid, vinyl propionate and cyclohexyl methacrylate in the propylene-based liquid, so that the finally prepared nano latex strong plugging agent has better plugging effect on the micro-nano gaps of the shale.

Thirdly, the nano latex with stable system is prepared by the method, the nano latex has more nano particles in the particles, the filtration loss rate of shale is lower, and the shear strength of the shale after the nano latex is applied to the shale is higher.

Detailed Description

The present invention will be described in further detail with reference to examples.