阅读说明：本技术 环保型水基钻井液用降滤失剂及其制备方法和钻井液 (Environment-friendly filtrate reducer for water-based drilling fluid, preparation method of filtrate reducer and drilling fluid ) 是由 蒲晓林 邵旭佳 任妍君 李方 王贵 于 2019-09-20 设计创作，主要内容包括：本发明提供了一种环保型水基钻井液用降滤失剂及其制备方法和环保型水基钻井液,解决了应用现有技术中的降滤失剂,滤饼质量不佳,滤失量较大的技术问题。所述降滤失剂是以低粘羧甲基纤维素为原料进行接枝改性,所用接枝单体为丙烯酰胺、2-丙烯酰胺基-2-甲基丙磺酸和二甲基二烯丙基氯化铵。应用本发明中的降滤失剂,能改善滤饼质量,降低滤失量；且环保、抗温性能优良。(The invention provides an environment-friendly filtrate reducer for water-based drilling fluid, a preparation method thereof and the environment-friendly water-based drilling fluid, and solves the technical problems of poor filter cake quality and large filtrate loss caused by the application of the filtrate reducer in the prior art. The filtrate reducer is prepared by taking low-viscosity carboxymethyl cellulose as a raw material to perform graft modification, wherein the grafting monomers are acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and dimethyl diallyl ammonium chloride. By applying the filtrate reducer disclosed by the invention, the quality of a filter cake can be improved, and the filtrate loss is reduced; and has environmental protection and excellent temperature resistance.)

1. An environment-friendly filtrate reducer for water-based drilling fluid is characterized in that: the low-viscosity carboxymethyl cellulose is used as a raw material for grafting modification, and the grafting monomers are acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and dimethyl diallyl ammonium chloride.

2. The environment-friendly fluid loss additive for water-based drilling fluid as claimed in claim 1, wherein: the grafting modification reaction is added with an initiator, and a solution polymerization method is adopted for grafting copolymerization.

3. The environment-friendly fluid loss additive for water-based drilling fluid as claimed in claim 2, wherein: the initiator is ammonium persulfate.

4. The environment-friendly fluid loss additive for water-based drilling fluid as claimed in claim 3, wherein: the mass ratio of the acrylamide to the 2-acrylamido-2-methylpropanesulfonic acid to the dimethyldiallylammonium chloride is 5.5-6.5: 1.5-3: 0.5-1.5.

5. The environmentally friendly fluid loss additive for water-based drilling fluids as claimed in any one of claims 2-4, wherein: the graft modification reaction is carried out in an aqueous solution having a pH of 6.5 to 7.5.

6. The environment-friendly fluid loss additive for water-based drilling fluid as claimed in claim 5, wherein: in the aqueous solution of the graft modification reaction, the total concentration of the graft monomer is 15 to 25 percent; the content of the low-viscosity carboxymethyl cellulose is 1.5-3%.

7. The environment-friendly fluid loss additive for water-based drilling fluid as claimed in claim 6, wherein: in the aqueous solution of the graft modification reaction, the dosage of the initiator is 0.15-0.25% of the total mass of the graft monomer.

8. The preparation method of the fluid loss additive for the environment-friendly water-based drilling fluid according to any one of claims 2 to 7, characterized by comprising the following steps: the method comprises the following steps:

(1) preparation of reagents:

weighing an initiator, dissolving the initiator in distilled water, and preparing an initiator solution; and dividing the initiator solution into two equal parts;

weighing 2-acrylamide-2-methylpropanesulfonic acid, dissolving the 2-acrylamide-2-methylpropanesulfonic acid in distilled water to prepare a 2-acrylamide-2-methylpropanesulfonic acid solution, and adjusting the pH value of the solution to 6.5-7.5;

weighing acrylamide and dimethyl diallyl ammonium chloride, dissolving in distilled water, and preparing an aqueous solution of the acrylamide and the dimethyl diallyl ammonium chloride;

(2) weighing distilled water and low-viscosity carboxymethyl cellulose, and adding the distilled water and the low-viscosity carboxymethyl cellulose into a reaction container; heating, controlling the temperature in the reaction vessel to be 30-40 ℃, and stirring;

(3) slowly adding low-viscosity carboxymethyl cellulose under the condition of stirring, and fully dissolving the low-viscosity carboxymethyl cellulose to form a uniform and transparent solution;

(4) continuing to heat up, and adding one part of the initiator solution prepared in the step (1) and the 2-acrylamide-2-methylpropanesulfonic acid solution prepared in the step (1) when the temperature in the reaction vessel reaches 65-75 ℃; keeping the temperature at 65-75 ℃, and reacting for 8-12 min;

(5) adding the other part of the initiator solution prepared in the step (1), keeping the temperature at 65-75 ℃, and reacting for 10-12 min;

(6) and (2) adding the acrylamide and the dimethyl diallyl ammonium chloride aqueous solution prepared in the step (1), keeping the temperature at 65-75 ℃, and fully reacting for 2-4 h under constant-speed stirring to obtain a gel liquid product, namely the filtrate reducer for the environment-friendly water-based drilling fluid.

9. The preparation method of the filtrate reducer for the environment-friendly water-based drilling fluid according to claim 8, characterized by comprising the following steps: in the step (1) and the step (2), NaOH solution is used for regulating the PH value.

10. An environment-friendly water-based drilling fluid is characterized in that: the components of the fluid loss additive comprise the environment-friendly fluid loss additive for water-based drilling fluid as defined in any one of claims 1 to 7.

Technical Field

The invention relates to a filtrate reducer, and in particular relates to a filtrate reducer for an environment-friendly water-based drilling fluid, a preparation method of the filtrate reducer and the environment-friendly water-based drilling fluid.

Background

During the drilling process, due to the action of the pressure difference, the water in the drilling fluid is inevitably lost to the stratum through the well wall, so that the drilling fluid loses water. As water enters the formation, clay particles in the drilling fluid adhere to the wellbore wall to form a "filter cake," forming a filter cake wellbore. As the well wall of the filter cake is much denser than the original well wall, the filter cake prevents the drilling fluid from further losing water on one hand and plays a role in protecting the well wall on the other hand. However, in the process of forming a filter cake well wall, the filtered water content is too much, the filter cake is too thick, and fine clay particles enter the stratum along with the water content, so that normal drilling is affected and the stratum is damaged.

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. It is clear that the fluid loss of a drilling fluid is closely related to the formation permeability. However, when the drilling fluid is lost, a filter cake is formed, and when the drilling fluid is lost again, the drilling fluid must pass through the formed filter cake. Thus, the main factor determining the magnitude of the fluid loss is the permeability of the filter cake. How to form a high quality filter cake with low permeability to prevent further loss of drilling fluid is one of the major issues to be considered in the formulation of drilling fluids.

In addition, the filtrate reducer is used as a first regulator of the drilling fluid performance, the environmental protection performance is also very important, most of the existing drilling fluid filtrate reducers have toxic groups, have biotoxicity, are not easy to degrade, can cause pollution to the environment, and simultaneously can also damage the quality of stratum and oil products,

in addition, fluid loss additives also need to have high temperature resistance.

The applicant has found that the prior art has at least the following technical problems:

1. in the filtrate reducer in the prior art, the quality of a filter cake is poor, and the filtrate loss is large;

2. the filtrate reducer in the prior art is mostly not environment-friendly, can pollute the environment and can also possibly damage the stratum and the quality of oil products;

3. most of filtrate reducers in the prior art have poor temperature resistance.

Disclosure of Invention

The invention aims to provide an environment-friendly filtrate reducer for water-based drilling fluid, a preparation method thereof and the environment-friendly water-based drilling fluid, so as to solve the technical problems of poor filter cake quality and large filtrate loss caused by the application of the filtrate reducer in the prior art. The technical effects that can be produced by the preferred technical scheme in the technical schemes provided by the invention are described in detail in the following.

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

the invention provides an environment-friendly filtrate reducer for water-based drilling fluid, which is prepared by taking low-viscosity carboxymethyl cellulose as a raw material to perform graft modification, wherein the grafting monomers are acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and dimethyl diallyl ammonium chloride.

Optionally or preferably, an initiator is added in the graft modification reaction, and a solution polymerization method is adopted for graft copolymerization.

Alternatively or preferably, the initiator is ammonium persulfate.

Alternatively or preferably, the mass ratio of the acrylamide to the 2-acrylamido-2-methylpropanesulfonic acid to the dimethyldiallylammonium chloride is 5.5 to 6.5: 1.5-3: 0.5-1.5.

Alternatively or preferably, the graft modification reaction is carried out in an aqueous solution having a pH of from 6.5 to 7.5.

Alternatively or preferably, in the aqueous solution of the graft modification reaction, the total concentration of the graft monomer is 15 to 25 percent; the content of the low-viscosity carboxymethyl cellulose is 1.5-3%.

Alternatively or preferably, in the aqueous solution of the graft modification reaction, the amount of the initiator is 0.15 to 0.25 percent of the total mass of the graft monomer.

The invention provides a preparation method of a filtrate reducer for an environment-friendly water-based drilling fluid, which comprises the following steps:

(1) preparation of reagents:

weighing an initiator, dissolving the initiator in distilled water, and preparing an initiator solution; and dividing the initiator solution into two equal parts;

weighing 2-acrylamide-2-methylpropanesulfonic acid, dissolving the 2-acrylamide-2-methylpropanesulfonic acid in distilled water to prepare a 2-acrylamide-2-methylpropanesulfonic acid solution, and adjusting the pH value of the solution to 6.5-7.5;

weighing acrylamide and dimethyl diallyl ammonium chloride, dissolving in distilled water, and preparing an aqueous solution of the acrylamide and the dimethyl diallyl ammonium chloride;

(2) weighing distilled water and low-viscosity carboxymethyl cellulose, and adding the distilled water and the low-viscosity carboxymethyl cellulose into a reaction container; heating, controlling the temperature in the reaction vessel to be 30-40 ℃, and stirring;

(3) slowly adding low-viscosity carboxymethyl cellulose under the condition of stirring, and fully dissolving the low-viscosity carboxymethyl cellulose to form a uniform and transparent solution;

(4) continuing to heat up, and adding one part of the initiator solution prepared in the step (1) and the 2-acrylamide-2-methylpropanesulfonic acid solution prepared in the step (1) when the temperature in the reaction vessel reaches 65-75 ℃; keeping the temperature at 65-75 ℃, and reacting for 8-12 min;

(5) adding the other part of the initiator solution prepared in the step (1), keeping the temperature at 65-75 ℃, and reacting for 10-12 min;

(6) and (2) adding the acrylamide and the dimethyl diallyl ammonium chloride aqueous solution prepared in the step (1), keeping the temperature at 65-75 ℃, and fully reacting for 2-4 h under constant-speed stirring to obtain a gel liquid product, namely the filtrate reducer for the environment-friendly water-based drilling fluid.

Optionally or preferably, in the step (1), the PH value is adjusted by using NaOH solution.

The invention provides an environment-friendly water-based drilling fluid, which comprises the filtrate reducer for the environment-friendly water-based drilling fluid.

Persulfate-initiated low viscosity Carboxylic acids in the present inventionThe mechanism of methylcellulose is: firstly persulfate generates-SO through pyrolysis₄*；-SO₄Reaction in water to produce OH radicals; OH radicals are used for abstracting-OH hydrogen atoms on the CMC molecular skeleton structure to form CMC-O primary radicals; then reacting with each grafting monomer. The specific reaction process is shown as the following formula:

S₂O₈ ^2-→2SO₄ ^-＊

SO₄ ^-*+H₂O→H⁺+SO₄ ^2-+HO^*

CMC-OH+HO^*→CMC-O^*+H₂O

based on the technical scheme, the embodiment of the invention can at least produce the following technical effects:

(1) the environment-friendly filtrate reducer for the water-based drilling fluid provided by the invention is prepared by taking low-viscosity carboxymethyl cellulose as a raw material to perform graft modification, and an adsorption group and a cation rigid group are introduced, so that the stability of the filtrate reducer is enhanced, the quality of a filter cake can be effectively improved in application, and the filtrate loss is reduced; the environment-friendly oil-water mixture is nontoxic and degradable, meets the environment-friendly requirement, does not pollute the environment, and does not damage the stratum and the quality of oil products; in addition, the temperature resistance of the filtrate reducer for the environment-friendly water-based drilling fluid can reach about 160 ℃, the temperature resistance of a system added with the drilling fluid can also reach about 150 ℃, and the filtrate reducer has good temperature resistance.

(2) According to the preparation method of the filtrate reducer for the environment-friendly water-based drilling fluid, the prepared filtrate reducer for the environment-friendly water-based drilling fluid is prepared by grafting and modifying low-viscosity carboxymethyl cellulose serving as a raw material, and an adsorption group and a cation rigid group are introduced, so that the stability of the filtrate reducer is enhanced, the quality of a filter cake can be effectively improved in application, and the filtrate loss is reduced; the environment-friendly oil-water mixture is nontoxic and degradable, meets the environment-friendly requirement, does not pollute the environment, and does not damage the stratum and the quality of oil products; in addition, the temperature resistance of the filtrate reducer for the environment-friendly water-based drilling fluid can reach about 160 ℃, the temperature resistance of a system added with the drilling fluid can also reach about 150 ℃, and the filtrate reducer has good temperature resistance.

(3) The environment-friendly water-based drilling fluid provided by the invention has the advantages that as the components are added with the fluid loss additive for the environment-friendly water-based drilling fluid, the quality of a filter cake can be effectively improved and the fluid loss is reduced in application; the added filtrate reducer for the environment-friendly water-based drilling fluid is nontoxic and degradable, meets the environment-friendly requirement, does not pollute the environment, and does not damage the stratum and the quality of oil products; in addition, the temperature resistance of the filtrate reducer for the environment-friendly water-based drilling fluid can reach about 160 ℃, the temperature resistance of a system added with the drilling fluid can also reach about 150 ℃, and the filtrate reducer has good temperature resistance.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a scanning electron microscope image of a low viscosity carboxymethylcellulose of the prior art;

FIG. 2 is a scanning electron microscope picture of the filtrate reducer for the environment-friendly water-based drilling fluid obtained in example 1 of the present invention;

FIG. 3 is a scanning electron micrograph of a filter cake in the comparative example;

FIG. 4 is a scanning electron micrograph of a filter cake obtained by using the environment-friendly water-based drilling fluid of example 5 of the present invention;

FIG. 5 is a graph showing the particle size distribution of a base slurry obtained by using the drilling fluid of the comparative example;

FIG. 6 is a plot of the particle size distribution of a base slurry obtained using the drilling fluid of example 5 of the present invention;

FIG. 7 is a graph of test results of the effect of aging temperature on API fluid loss.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.

Description of the reagents:

low viscosity carboxymethyl cellulose: tianjin chemical reagent plant, LV-CMC

The percentage concentration of the sodium hydroxide solution is 5%;

the dimethyl diallyl ammonium chloride adopts 60 percent of dimethyl diallyl ammonium chloride aqueous solution.