阅读说明：本技术 一种高分子降滤失剂及钻井液 (Polymer filtrate reducer and drilling fluid ) 是由 樊彦龙 梁大川 于 2021-01-21 设计创作，主要内容包括：本发明提供了一种高分子降滤失剂及钻井液,所述的高分子降滤失剂采用以下步骤制备而成：取丙烯酰胺、对苯乙烯磺酸钠、甲基丙烯酸加入到水中,搅拌均匀后加入氧化石墨烯,密闭超声分散,得到氧化石墨烯分散液；将氧化石墨烯分散液pH调节为9-12,加入氧化还原引发剂,并升温反应,反应结束后,降低温度至30-50℃并恒温熟化2-5h,得到聚合物胶体；将聚合物胶体用乙醇、去离子水洗涤数次,干燥至恒重,并粉碎造粒即得降滤失剂。将降滤失剂直接加入钻井液即可使用。本发明制得的高分子降滤失剂,不仅能够极大的降低钻井液的滤失量,同时还具有较好的抗高温性能,本发明提供的钻井液,不仅能够在井壁上形成优质的泥饼,提高泥饼的稳定性,同时其滤失量较低。(The invention provides a polymer filtrate reducer and drilling fluid, wherein the polymer filtrate reducer is prepared by the following steps: adding acrylamide, sodium p-styrene sulfonate and methacrylic acid into water, uniformly stirring, adding graphene oxide, and performing closed ultrasonic dispersion to obtain a graphene oxide dispersion liquid; adjusting the pH value of the graphene oxide dispersion liquid to 9-12, adding a redox initiator, heating for reaction, after the reaction is finished, reducing the temperature to 30-50 ℃, and curing at constant temperature for 2-5h to obtain polymer colloid; and washing the polymer colloid with ethanol and deionized water for several times, drying to constant weight, and crushing and granulating to obtain the filtrate reducer. The filtrate reducer can be directly added into the drilling fluid for use. The polymer filtrate reducer prepared by the invention not only can greatly reduce the filtrate loss of the drilling fluid, but also has better high-temperature resistance.)

1. The polymer filtrate reducer is characterized by being prepared by the following steps:

s1, adding 4-5 parts by weight of acrylamide, 5-6 parts by weight of sodium p-styrene sulfonate and 5-8 parts by weight of methacrylic acid into 50 parts by weight of water, uniformly stirring, adding 0.5-1 part by weight of graphene oxide, and carrying out closed ultrasonic dispersion to obtain a graphene oxide dispersion liquid;

s2, taking the graphene oxide dispersion liquid obtained in the step S1, adjusting the pH value of the graphene oxide dispersion liquid to 9-12, adding a redox initiator, heating to 50-60 ℃, reacting for 3-8 hours, after the reaction is finished, reducing the temperature to 30-50 ℃, and curing at constant temperature for 2-5 hours to obtain a polymer colloid;

s3, washing the polymer colloid obtained in the step S2 with ethanol and deionized water for a plurality of times, drying to constant weight, and crushing and granulating to obtain the fluid loss additive.

2. The polymeric fluid loss additive according to claim 1, wherein the redox initiator is a combination of sodium sulfite and any one of ammonium persulfate, or potassium persulfate.

3. The polymeric fluid loss additive according to claim 1, wherein the drying temperature in step S3 is 60-70 ℃.

4. The drilling fluid is characterized by comprising the following components in parts by weight: 100 parts of water, 2-12 parts of bentonite, 0.1-1 part of sodium carbonate, 0.001-0.3 part of sodium hydroxide, 0.2-4 parts of coating agent, 3-10 parts of fluid loss additive prepared by the method of any one of claims 1-3, 1-8 parts of inhibitor, 0.5-9 parts of plugging anti-collapse agent, 1-10 parts of viscosity reducer, 2-6 parts of wall fixing agent, 1-5 parts of diluent, 2-9 parts of lubricant and 10-50 parts of weighting agent.

5. The drilling fluid according to claim 4, wherein the drilling fluid comprises the following components in parts by weight: 100 parts of water, 4-10 parts of bentonite, 0.2-0.9 part of sodium carbonate, 0.002-0.2 part of sodium hydroxide, 1-3 parts of coating agent, 4-9 parts of filtrate reducer, 2-6 parts of inhibitor, 2-7 parts of plugging anti-collapse agent, 2-8 parts of viscosity reducer, 3-5 parts of wall fixing agent, 2-4 parts of diluent, 3-8 parts of lubricant and 12-48 parts of weighting agent.

6. The drilling fluid of claim 4 or 5, wherein the coating agent is FA-367; the plugging anti-collapse agent is at least one of a self-bionic plugging anti-collapse agent, water-dispersible emulsified asphalt powder SFT or a non-fluorescent white asphalt NFA-25 inhibiting plugging anti-collapse agent; the inhibitor is at least one of sulfonated asphalt FT-1, propionamide or potassium chloride; the viscosity reducer is at least one of sulfonated lignite, an oligomer viscosity reducer XB-40 or a composite ionic polymer viscosity reducer PSC 90-6; the wall-fixing agent is a modified resin polymer HLGB-2; the diluent is at least one of a silyl ether polymer, SMT-T or XG-1; the lubricant is at least one of sulfonated tall oil pitch, phosphate ester or sulfurized grease; the weighting agent is at least one of barite, magnetite powder or ilmenite powder.

Technical Field

The invention belongs to the technical field of drilling fluid, and particularly relates to a high-molecular fluid loss additive and drilling fluid comprising the same.

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 filtration loss of the drilling fluid and the formation of a filter cake are inevitable during the drilling process, and the filter cake can be formed through the filtration loss to protect the well wall. However, the shale is easy to expand and collapse due to the excessive drilling fluid filtration loss, so that the well wall is unstable. In addition, the filter cake thickens while the fluid loss increases, which reduces the well diameter and causes sticking. However, the filter cake of the existing drilling fluid is formed underground, and the filter loss of the drilling fluid is relatively large.

Disclosure of Invention

In order to solve the problems, the invention provides a high-molecular filtrate reducer which can ensure that the drilling fluid has smaller filtrate loss while ensuring that the drilling fluid forms a filter cake.

The technical scheme of the invention is as follows: a polymer filtrate reducer is prepared by the following steps:

s1, adding 4-5 parts by weight of acrylamide, 5-6 parts by weight of sodium p-styrene sulfonate and 5-8 parts by weight of methacrylic acid into 50 parts by weight of water, uniformly stirring, adding 0.5-1 part by weight of graphene oxide, and carrying out closed ultrasonic dispersion to obtain a graphene oxide dispersion liquid;

s2, taking the graphene oxide dispersion liquid obtained in the step S1, adjusting the pH value of the graphene oxide dispersion liquid to 9-12, adding a redox initiator, heating to 50-60 ℃, reacting for 3-8 hours, after the reaction is finished, reducing the temperature to 30-50 ℃, and curing at constant temperature for 2-5 hours to obtain a polymer colloid;

s3, washing the polymer colloid obtained in the step S2 with ethanol and deionized water for a plurality of times, drying to constant weight, and crushing and granulating to obtain the fluid loss additive.

Further, the redox initiator is a combination of sodium sulfite and any one of ammonium persulfate, ammonium persulfate or potassium persulfate.

Further, in the step S3, the drying temperature is 60 to 70 ℃.

The invention also aims to provide a drilling fluid with low filtration loss and good salt resistance, which comprises the following components in parts by weight: 100 parts of water, 2-12 parts of bentonite, 0.1-1 part of sodium carbonate, 0.001-0.3 part of sodium hydroxide, 0.2-4 parts of coating agent, 3-10 parts of the filtrate reducer, 1-8 parts of inhibitor, 0.5-9 parts of plugging anti-collapse agent, 1-10 parts of viscosity reducer, 2-6 parts of wall-fixing agent, 1-5 parts of diluent, 2-9 parts of lubricant and 10-50 parts of weighting agent.

Further, the drilling fluid comprises the following components in parts by weight: 100 parts of water, 4-10 parts of bentonite, 0.2-0.9 part of sodium carbonate, 0.002-0.2 part of sodium hydroxide, 1-3 parts of coating agent, 4-9 parts of filtrate reducer, 2-6 parts of inhibitor, 2-7 parts of plugging anti-collapse agent, 2-8 parts of viscosity reducer, 3-5 parts of wall fixing agent, 2-4 parts of diluent, 3-8 parts of lubricant and 12-48 parts of weighting agent.

Further, the coating agent is FA-367; the plugging anti-collapse agent is at least one of a self-bionic plugging anti-collapse agent, water-dispersible emulsified asphalt powder SFT or a non-fluorescent white asphalt NFA-25 inhibiting plugging anti-collapse agent; the inhibitor is at least one of sulfonated asphalt FT-1, propionamide or potassium chloride; the viscosity reducer is at least one of sulfonated lignite, an oligomer viscosity reducer XB-40 or a composite ionic polymer viscosity reducer PSC 90-6; the wall-fixing agent is a modified resin polymer HLGB-2; the diluent is at least one of a silyl ether polymer, SMT-T or XG-1; the lubricant is at least one of sulfonated tall oil pitch, phosphate ester or sulfurized grease; the weighting agent is at least one of barite, magnetite powder or ilmenite powder.

The invention has the beneficial effects that: the polymer filtrate reducer prepared by the invention not only can greatly reduce the filtrate loss of the drilling fluid, but also has better high-temperature resistance; the drilling fluid provided by the invention can form high-quality mud cakes on a well wall, improves the stability of the mud cakes, has low filtration loss and also has good salt resistance.

Detailed Description

In order to make the technical scheme and technical advantages of the invention clearer, the following will clearly and completely describe the technical scheme in the implementation process of the invention in combination with the practical application process of the invention in the development of certain compact oil reservoir in Xinjiang.

The various chemical feedstocks in this example, unless otherwise specified, were chemically pure, with acrylamide purchased from a Zibo Oriental plant; sodium p-styrene sulfonate is commercially available from Condidis chemical Co., Ltd, Hubei; the sodium p-styrene sulfonate is prepared by removing hydrogen bromide from p-bromoethylbenzene sulfonic acid under the action of sodium hydroxide, and is white to yellowish powder; methacrylic acid is available from Junxin chemical Co., Ltd, Shandong; sodium bisulfite was purchased from Shanghai reagent factory in China medicine.

Example 1

Preparing a polymer filtrate reducer:

s1, adding 40g of acrylamide, 50g of sodium p-styrene sulfonate and 60g of methacrylic acid into 500mL of water, adding 6g of graphene oxide, and performing ultrasonic dispersion on the graphene oxide in a closed state to obtain a graphene oxide dispersion liquid.

S2, adjusting the pH of the graphene oxide dispersion liquid obtained in the S1 to 10 by using a sodium hydroxide solution in a nitrogen atmosphere, adding a sodium sulfite-potassium persulfate redox initiator in a ratio of 1:1.4, heating to 55 ℃, reacting for 6 hours, observing that the reaction liquid becomes viscous at the moment, stopping the reaction, and curing at constant temperature of 45 ℃ for 4 hours to obtain the polymer colloid.

S3, washing the polymer colloid in the step S2 with ethanol and deionized water for 3 times in sequence, performing suction filtration, drying the solid phase at 60 ℃ to constant weight, and then crushing and granulating to obtain the polymer fluid loss agent A1.

Preparing the drilling fluid:

1. adding 700g of bentonite and 50g of sodium carbonate into 10L of water, stirring for 6 hours, and standing for 24 hours to form base slurry;

2. under the condition of high-speed stirring, 100g of coating agent FA-367, 400g of water-dispersible emulsified asphalt powder SFT, 300g of sulfonated asphalt FT-1, 300g of sulfonated lignite, 400g of modified resin polymer HLGB-2, 300g of SMT-T, 400g of sulfonated tall oil asphalt, 2000g of barite and 60g of the polymer filtrate reducer prepared in the above steps are sequentially added into the base slurry, the stirring is continued for 30min, and the pH value of the polymer filtrate reducer is adjusted to 11 by using sodium hydroxide, so that the drilling fluid S1 of the embodiment is obtained.

Examples 2-4 were formed in the drilling fluid by varying the addition of each material and pH to prepare different polymeric fluid loss additives according to the procedure in example 1, while varying the addition of each material so that the addition of at least one of the materials in the polymeric fluid loss additive does not form comparative examples 1-2 within the scope of the present invention, the addition of each material being as shown in the following table:

TABLE 1 addition of substances for the preparation of polymeric fluid loss additives in examples 1-4 and comparative examples 1-2

To further illustrate the technical effects of the present invention, specific tests are used to describe the same.

Fluid loss test

The effect of the invention is illustrated by measuring the fluid loss of the drilling fluid and the fluid loss after aging for 8 hours at 200 ℃, in the test process, the bentonite content of the base slurry is 6%, the mineralization degree is 50000mg/L, and the test instrument is a high-temperature high-pressure fluid loss instrument. Specific test results are shown in table 2.

TABLE 2 fluid loss test results for inventive and comparative examples

Numbering	Example 1	Example 2	Example 3	Example 4	Comparative example 1	Comparative example 2
							Fluid loss/mL before aging	4.5	5	3	4	18	15
Filtration loss/mL after aging	5.5	6	4	5.5	23	21

As can be seen from Table 2, the fluid loss additive of the invention has good fluid loss effect and good high temperature resistance, while the fluid loss additives of comparative example 1 and comparative example 2 have poor effects due to poor mixture ratio of the components.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.