阅读说明：本技术 一种水基钻井液及其应用 (Water-based drilling fluid and application thereof ) 是由 于建涛 邓明毅 胡书宝 朱庆忠 张锐锋 闫睿昶 游靖 唐鸿斌 张彬 盛晨 于 2020-06-10 设计创作，主要内容包括：本发明公开了一种水基钻井液及其应用,属于钻井技术领域。该水基钻井液包括以下重量份的组分：100重量份的水、2-15重量份的膨润土、1-10重量份的磺甲基酚醛树脂、1-10重量份的磺化褐煤、1-20重量份的抗高温流型调节剂、0.5-5重量份的降滤失剂、10-50重量份的复配封堵剂、5-30重量份的重晶石。其中,抗高温流型调节剂为2-丙烯酰胺-2-甲基丙磺酸/N,N-二甲基丙烯酰胺/二甲基二烯丙基氯化铵/N-乙烯基吡咯烷酮的四元共聚物。该水基钻井液具有低密度且抗高温,适用于深井、超深井钻井作业,能够有效解决水基钻井液高温减稠问题。(The invention discloses a water-based drilling fluid and application thereof, belonging to the technical field of drilling. The water-based drilling fluid comprises the following components in parts by weight: 100 parts of water, 2-15 parts of bentonite, 1-10 parts of sulfomethyl phenolic resin, 1-10 parts of sulfonated lignite, 1-20 parts of high-temperature resistant flow pattern regulator, 0.5-5 parts of fluid loss additive, 10-50 parts of compound plugging agent and 5-30 parts of barite. Wherein the high-temperature resistant flow pattern regulator is a quadripolymer of 2-acrylamide-2-methylpropanesulfonic acid/N, N-dimethylacrylamide/dimethyldiallylammonium chloride/N-vinyl pyrrolidone. The water-based drilling fluid has low density and high temperature resistance, is suitable for drilling operation of deep wells and ultra-deep wells, and can effectively solve the problem of high-temperature thickening reduction of the water-based drilling fluid.)

1. The water-based drilling fluid is characterized by comprising the following components in parts by weight:

100 parts of water, 2-15 parts of bentonite, 1-10 parts of sulfomethyl phenolic resin, 1-10 parts of sulfonated lignite, 1-20 parts of high-temperature resistant flow pattern regulator, 0.5-5 parts of fluid loss additive, 10-50 parts of compound plugging agent and 5-30 parts of barite;

wherein the high-temperature-resistant flow pattern regulator is a quadripolymer of 2-acrylamide-2-methylpropanesulfonic acid/N, N-dimethylacrylamide/dimethyldiallylammonium chloride/N-vinyl pyrrolidone.

2. The water-based drilling fluid according to claim 1, wherein the high temperature resistant flow pattern modifier is prepared by the following method:

neutralizing 2-acrylamide-2-methylpropanesulfonic acid to obtain a neutralization reaction product;

mixing the neutralization reaction product, N-dimethylacrylamide, dimethyl diallyl ammonium chloride and N-vinyl pyrrolidone according to a mass ratio, putting the mixture into a three-neck flask, and heating and stirring the mixture under the condition of introducing nitrogen into the three-neck flask to obtain a mixed solution;

and adding an initiator into the mixed solution for reaction, and sequentially drying and refining reaction products generated by the reaction to obtain the high-temperature-resistant flow pattern regulator.

3. The water-based drilling fluid of claim 2, wherein the neutralization treatment comprises: mixing the 2-acrylamide-2-methylpropanesulfonic acid with a sodium hydroxide solution, and stirring for 10-60 minutes at the temperature of 40-60 ℃ and the stirring speed of 1000-2000 rpm.

4. The water-based drilling fluid according to claim 2, wherein the mass ratio of the neutralization reaction product, N-dimethylacrylamide, dimethyldiallylammonium chloride and N-vinylpyrrolidone is 1: (0.5-1.5): (0.5-1.5): (2-3);

and heating to 60-80 ℃ under the condition of introducing nitrogen into the three-neck flask, and simultaneously stirring at the stirring speed of 1000-2000 rpm for 20-60 minutes to obtain the mixed solution.

5. The water-based drilling fluid of claim 2, wherein the adding of the initiator to the mixed liquor for reaction comprises:

adding ammonium persulfate-sodium bisulfite into the mixed solution as the initiator, carrying out the reaction at the temperature of 60-80 ℃ and the stirring speed of 1000-2000 r/min, and controlling the reaction time to be 200-280 min.

6. The water-based drilling fluid according to claim 2, wherein the reaction product generated by the reaction is subjected to drying treatment and refining treatment in sequence, and the drying treatment and the refining treatment comprise:

carrying out the drying treatment on the reaction product in a vacuum drying box, wherein the drying temperature is 30-40 ℃, and the drying time is 300-360 minutes;

and sequentially crushing and grinding the dried reaction product to be used as the refining treatment.

7. The water-based drilling fluid of claim 1, wherein the fluid loss additive is sodium carboxymethyl starch.

8. The water-based drilling fluid according to claim 1, wherein the compound plugging agent is prepared from the following components in a mass ratio of 1: (1-2) a mixture of 400 mesh calcium carbonate and 1250 mesh calcium carbonate.

9. The water-based drilling fluid of any one of claims 1-8, wherein the water-based drilling fluid has a density of 1.05g/cm³-1.25g/cm³；

The pH value of the water-based drilling fluid is 7-9.

10. Use of the water-based drilling fluid according to any one of claims 1 to 9 in deep and ultra-deep well drilling operations.

Technical Field

The invention relates to the technical field of drilling, in particular to a water-based drilling fluid and application thereof.

Background

In the drilling engineering of ultra-deep wells, low-density and high-temperature-resistant water-based drilling fluid is generally used to adapt to the ultra-high temperature environment caused by ultra-deep wells, so that it is necessary to provide a water-based drilling fluid suitable for high temperature resistance.

The related art discloses an ultra-high temperature resistant water-based drilling fluid, which comprises: 1-4% of bentonite and sepiolite composite base pulp, 0.1-0.3% of pH regulator, 0.2-1.2% of ultrahigh-temperature medium-molecular polymer filtrate reducer, 0.05-0.6% of ultrahigh-temperature polymer deflocculant, 2-6% of sulfomethylated phenolic resin, 2-6% of sulfomethylated lignite resin, 1-4% of high-temperature plugging anti-collapse agent, 1-4% of ultrahigh-temperature lubricant, 0.1-1.2% of high-temperature stabilizer and 0-32% of salt-proof dissolving agent.

In the process of implementing the invention, the inventor finds that at least the following problems exist in the related art:

when the water-based drilling fluid provided by the related technology is used for a long time under the ultra-high temperature condition, the problem of high temperature thickening reduction is easy to occur.

Disclosure of Invention

In view of the above, the present invention provides a water-based drilling fluid and an application thereof, which can solve the above technical problems.

Specifically, the method comprises the following technical scheme:

in one aspect, embodiments of the present invention provide a water-based drilling fluid, which includes the following components in parts by weight:

100 parts of water, 2-15 parts of bentonite, 1-10 parts of sulfomethyl phenolic resin, 1-10 parts of sulfonated lignite, 1-20 parts of high-temperature resistant flow pattern regulator, 0.5-5 parts of fluid loss additive, 10-50 parts of compound plugging agent and 5-30 parts of barite;

wherein the high-temperature-resistant flow pattern regulator is a quadripolymer of 2-acrylamide-2-methylpropanesulfonic acid/N, N-dimethylacrylamide/dimethyldiallylammonium chloride/N-vinyl pyrrolidone.

In one possible implementation, the high temperature resistant flow pattern modifier is prepared by the following method:

neutralizing 2-acrylamide-2-methylpropanesulfonic acid to obtain a neutralization reaction product;

mixing the neutralization reaction product, N-dimethylacrylamide, dimethyl diallyl ammonium chloride and N-vinyl pyrrolidone according to a mass ratio, putting the mixture into a three-neck flask, and heating and stirring the mixture under the condition of introducing nitrogen into the three-neck flask to obtain a mixed solution;

and adding an initiator into the mixed solution for reaction, and sequentially drying and refining reaction products generated by the reaction to obtain the high-temperature-resistant flow pattern regulator.

In one possible implementation, the neutralizing process includes: mixing the 2-acrylamide-2-methylpropanesulfonic acid with a sodium hydroxide solution, and stirring for 10-60 minutes at the temperature of 40-60 ℃ and the stirring speed of 1000-2000 rpm.

In one possible implementation, the mass ratio of the neutralization reaction product, N-dimethylacrylamide, dimethyldiallylammonium chloride, N-vinylpyrrolidone is 1: (0.5-1.5): (0.5-1.5): (2-3);

and heating to 60-80 ℃ under the condition of introducing nitrogen into the three-neck flask, and simultaneously stirring at the stirring speed of 1000-2000 rpm for 20-60 minutes to obtain the mixed solution.

In a possible implementation manner, the adding an initiator to the mixed solution for reaction includes:

adding ammonium persulfate-sodium bisulfite into the mixed solution as the initiator, carrying out the reaction at the temperature of 60-80 ℃ and the stirring speed of 1000-2000 r/min, and controlling the reaction time to be 200-280 min.

In a possible implementation manner, the sequentially performing a drying process and a refining process on a reaction product generated by the reaction includes:

carrying out the drying treatment on the reaction product in a vacuum drying box, wherein the drying temperature is 30-40 ℃, and the drying time is 300-360 minutes;

and sequentially crushing and grinding the dried reaction product to be used as the refining treatment.

In one possible implementation, the fluid loss additive is sodium carboxymethyl starch.

In one possible implementation manner, the compound plugging agent is prepared by mixing the following components in a mass ratio of 1: (1-2) a mixture of 400 mesh calcium carbonate and 1250 mesh calcium carbonate.

In one possible implementation, the water-based drilling fluid has a density of 1.05g/cm³-1.25g/cm³；

The pH value of the water-based drilling fluid is 7-9.

On the other hand, the embodiment of the invention also provides the application of any one of the water-based drilling fluids in drilling operation of deep wells and ultra-deep wells.

The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:

according to the water-based drilling fluid provided by the embodiment of the invention, water, bentonite, sulfomethyl phenolic resin, sulfonated lignite, a high-temperature resistant flow pattern regulator, a filtrate reducer, a compound plugging agent and barite are compounded according to the weight ratio, so that the water-based drilling fluid is high-temperature resistant and low-density, and is particularly suitable for drilling operation of deep wells and ultra-deep wells. The high-temperature-resistant flow pattern regulator is a quadripolymer of 2-acrylamide-2-methylpropanesulfonic acid/N, N-dimethylacrylamide/dimethyldiallylammonium chloride/N-vinyl pyrrolidone, quaternary ammonium groups contained in the quadripolymer have positive electricity, can be adsorbed to the surfaces of clay particles before water molecules, neutralize the electronegativity of the clay particles, and are matched with anion hydration groups, the clay particles are tightly coated by thick and compact hydration layers, so that the flocculation tendency among the clay particles is weakened, and the problem of high-temperature thickening reduction of the water-based drilling fluid can be effectively solved.

Detailed Description

In order to make the technical solutions and advantages of the present invention more clear, embodiments of the present invention will be described in further detail below.

In one aspect, embodiments of the present invention provide a water-based drilling fluid, which includes the following components in parts by weight:

100 parts of water, 2-15 parts of bentonite, 1-10 parts of sulfomethyl phenolic resin, 1-10 parts of sulfonated lignite, 1-20 parts of high-temperature resistant flow pattern regulator, 0.5-5 parts of fluid loss additive, 10-50 parts of compound plugging agent and 5-30 parts of barite.

Wherein the high-temperature resistant flow pattern regulator is a quadripolymer of 2-acrylamide-2-methylpropanesulfonic acid/N, N-dimethylacrylamide/dimethyldiallylammonium chloride/N-vinyl pyrrolidone.

According to the water-based drilling fluid provided by the embodiment of the invention, water, bentonite, sulfomethyl phenolic resin, sulfonated lignite, a high-temperature resistant flow pattern regulator, a filtrate reducer, a compound plugging agent and barite are compounded according to the weight ratio, so that the water-based drilling fluid is high-temperature resistant and low-density, and is particularly suitable for drilling operation of deep wells and ultra-deep wells. The high-temperature-resistant flow pattern regulator is a quadripolymer of 2-acrylamide-2-methylpropanesulfonic acid/N, N-dimethylacrylamide/dimethyldiallylammonium chloride/N-vinyl pyrrolidone, quaternary ammonium groups contained in the quadripolymer have positive electricity, can be adsorbed to the surfaces of clay particles before water molecules, neutralize the electronegativity of the clay particles, and are matched with anion hydration groups, the clay particles are tightly coated by thick and compact hydration layers, so that the flocculation tendency among the clay particles is weakened, and the problem of high-temperature thickening reduction of the water-based drilling fluid can be effectively solved.

The high-temperature thickening of the water-based drilling fluid means that the viscosity yield value of the drilling fluid is reduced, so that the carrying and well wall cleaning capabilities are reduced.

In one possible design, based on 100 parts by weight of water, the bentonite content is 3-5 parts by weight, the sulfomethyl phenolic resin content is 4-6 parts by weight, the sulfonated lignite content is 4-6 parts by weight, the high-temperature resistant flow pattern regulator content is 7-9 parts by weight, the filtrate reducer content is 2-3 parts by weight, the compound plugging agent content is 26-30 parts by weight, and the barite content is 18-20 parts by weight.

Wherein the water used can be tap water, and the bentonite used can be sodium bentonite purchased from Bentonite GmbH in Noxizijie. The sulfomethyl phenolic resin used in the embodiment of the invention is one or more of sulfomethyl phenolic resin I type, sulfomethyl phenolic resin II type and/or sulfomethyl phenolic resin III type, can be purchased from Sichuan southwest stone Dajinniu petroleum technology Co., Ltd, and can be sulfomethyl phenolic resin III type with the model of SMP-III in order to better compound other components.

In order to not pollute the stratum environment, the sulfonated lignite is chromium-free sulfonated lignite which can be purchased from Sichuan southwest stone Taurus oil science and technology limited and is of the type M-SMC.

The filtrate reducer is sodium carboxymethyl starch, has high temperature resistance, and can be purchased from Sichuan southwest stone Dajinniu Petroleum science and technology Limited company with the model of HIS.

The used compound plugging agent is 400-mesh calcium carbonate and 1250-mesh calcium carbonate according to the mass ratio of 1: (1-2), wherein the calcium carbonate with different meshes can be obtained from Changxing Longfeng powder materials Co.

The barite used was barium sulfate granules, available from Cishi mineral processing plants in Lingshou county.

For the high-temperature-resistant flow pattern regulator which is used for solving the problem of high-temperature thickening reduction of the water-based drilling fluid, the high-temperature-resistant flow pattern regulator can be prepared by the following method, and specifically comprises the following steps:

step 1: neutralizing the 2-acrylamide-2-methylpropanesulfonic acid to obtain a neutralization reaction product.

Illustratively, the neutralization process includes: mixing 2-acrylamide-2-methylpropanesulfonic acid with a sodium hydroxide solution (for example, a sodium hydroxide solution with a mass concentration of 40%) and stirring for 10-60 minutes at a temperature of 40-60 ℃ and a stirring speed of 1000-2000 rpm. At this time, the obtained neutralization reaction product was sodium 2-acrylamido-2-methylpropanesulfonate.

For example, the temperature of the above-mentioned neutralization treatment may be 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃ or the like, the stirring rate may be 1000 rpm, 1200 rpm, 1500 rpm, 1800 rpm, 2000 rpm or the like, and the stirring time may be 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes or the like.

Step 2: and mixing the neutralization reaction product, N-dimethylacrylamide, dimethyl diallyl ammonium chloride and N-vinyl pyrrolidone according to a mass ratio, putting the mixture into a three-neck flask, and heating and stirring the mixture under the condition of introducing nitrogen into the three-neck flask to obtain a mixed solution.

Wherein the mass ratio of the neutralization reaction product, N-dimethylacrylamide, dimethyl diallyl ammonium chloride and N-vinyl pyrrolidone is 1: (0.5-1.5): (0.5-1.5): (2-3), for example, 1:1:1:2.5, 1:0.8:1:2, 1:1.5:0.5:2.5, 1:1.5:1:3, etc.

Heating to 60-80 ℃ under the condition of introducing nitrogen into the three-neck flask, and stirring for 20-60 minutes at the stirring speed of 1000-2000 rpm to obtain a mixed solution.

For example, the temperature may be raised to 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃ and the like, the stirring rate may be 1000 rpm, 1200 rpm, 1500 rpm, 1800 rpm, 2000 rpm and the like, and the stirring time may be 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes and the like.

And step 3: adding an initiator into the mixed solution for reaction, and sequentially drying and refining reaction products generated by the reaction to obtain the high-temperature-resistant flow type regulator.

For the reaction in which the above initiator participates, it may include: adding ammonium persulfate-sodium bisulfite into the mixed solution as an initiator, reacting at the temperature of 60-80 ℃ and the stirring speed of 1000-2000 r/min, and controlling the reaction time to be 200-280 min.

For example, the temperature may be 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃ or the like, the stirring rate may be 1000 rpm, 1200 rpm, 1500 rpm, 1800 rpm, 2000 rpm or the like, and the reaction time may be 200 minutes, 210 minutes, 220 minutes, 230 minutes, 240 minutes/250 minutes, 260 minutes, 270 minutes or the like.

Wherein the adding amount of the ammonium persulfate-sodium bisulfite is 0.1 to 1.5 percent of the total mass of the reaction monomers in the mixed solution.

Further, the reaction product generated by the reaction is sequentially subjected to drying treatment and refining treatment, and the method comprises the following steps:

drying the reaction product in a vacuum drying oven, wherein the drying temperature is 30-40 ℃, and the drying time is 300-360 minutes; and (4) sequentially crushing and grinding the dried reaction product to be used as thinning treatment.

Through the preparation method, the high-temperature-resistant flow pattern regulator expected by the embodiment of the invention can be prepared.

For the water-based drilling fluid provided by the embodiment of the invention, the density is 1.05g/cm³-1.25g/cm³And the pH value of the water-based drilling fluid is 7-9, so that the water-based drilling fluid is high-temperature resistant and has low density, and the water-based drilling fluid is suitable for drilling operation of deep wells and ultra-deep wells and cannot damage stratums.

The water-based drilling fluid provided by the embodiment of the invention can be prepared by the following method:

the method comprises the steps of measuring prehydrated bentonite slurry according to the weight ratio, adding sulfomethyl phenolic resin, sulfonated lignite, a high-temperature-resistant flow pattern regulator, a filtrate reducer, a compound plugging agent and barite in a stirring environment, and uniformly stirring to prepare the water-based drilling fluid expected by the embodiment of the invention.

Wherein, the bentonite is prehydrated by water to obtain bentonite slurry with more uniform components. The pre-hydration time may be 24 to 36 hours, for example, 24 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, and the like.

In order to obtain a water-based drilling fluid with uniform components and desired texture, the stirring rate is 2000-4000 rpm, for example, 2000 rpm, 2300 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 3800 rpm, 4000 rpm, etc. when the components are stirred.

The temperature of the stirring environment is 20-30 deg.C, such as 20 deg.C, 23 deg.C, 25 deg.C, 27 deg.C, 29 deg.C, 30 deg.C, etc.

The above components may be sequentially added to the bentonite slurry, and for example, sulfomethyl phenol resin, sulfonated lignite, high temperature resistant flow pattern modifier, fluid loss additive, built plugging agent, and barite may be sequentially added to the bentonite slurry in the following order. Wherein the feeding time interval of each component is 20-40 minutes, for example, each component can be fully dissolved into the drilling fluid to play a better effect.

In another aspect, embodiments of the present invention further provide an application of any one of the above water-based drilling fluids in drilling operations of deep wells and ultra-deep wells.

The water-based drilling fluid provided by the embodiment of the invention has low density and high temperature resistance, and is particularly suitable for drilling operation of deep wells and ultra-deep wells.

Because the high-temperature-resistant flow pattern regulator adopted by the water-based drilling fluid provided by the embodiment of the invention contains the quaternary ammonium groups with positive electricity, the quaternary ammonium groups can be adsorbed to the surfaces of the clay particles before water molecules, the electronegativity of the clay particles is neutralized, and meanwhile, the clay particles are tightly coated by a thick and compact hydration layer by matching with anion hydration groups, so that the flocculation tendency among the clay particles is weakened. Meanwhile, the water-based drilling fluid has good rheological property and fluid loss property in a high-temperature environment by matching with the synergistic compounding effect of all components of the water-based drilling fluid, so that the problem of high-temperature thickening of the water-based drilling fluid is effectively solved.

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

Preparation example

The preparation example is used for preparing the high-temperature-resistant flow pattern regulator, and the specific operation steps are as follows:

(1) weighing 20g of 2-acrylamide-2-methylpropanesulfonic acid, placing the 2-acrylamide-2-methylpropanesulfonic acid into a beaker, adding 50ml of 40.0% sodium hydroxide solution, and carrying out neutralization reaction for 30 minutes at the temperature of 50 ℃ and the stirring speed of 1500 rpm to obtain a neutralization reaction product;

(2) and (2) mixing the neutralization reaction product obtained in the step (1) (namely 20g of 2-acrylamide-2-methyl sodium propanesulfonate) with 20g of N, N-dimethylacrylamide, 20g of dimethyl diallyl ammonium chloride and 40 g of N-vinyl pyrrolidone, putting the mixture into a three-neck flask, heating to 65 ℃ under the condition of introducing nitrogen into the three-neck flask, and stirring at the stirring speed of 1500 revolutions per minute to obtain a mixed solution.

(3) And (3) adding 1 g of ammonium persulfate-sodium bisulfite into the mixed solution obtained in the step (2), and reacting for 240 minutes at the temperature of 65 ℃ and the stirring speed of 1500 revolutions per minute to obtain a reaction product.

(4) And (4) taking out the reaction product obtained in the step (3), placing the reaction product into a vacuum drying oven, drying the reaction product for 350 minutes at the temperature of 35 ℃, and crushing and grinding the reaction product to obtain the high-temperature-resistant flow type regulator.

Example 1

The embodiment provides an ultrahigh-temperature-resistant low-density water-based drilling fluid, which is prepared by the following steps:

(1) 100 g of tap water and 4 g of sodium bentonite are stirred for 30 minutes at the speed of 3000 rpm in the environment of 25 ℃, and then are kept stand for 24 hours for prehydration, so as to obtain a mixed solution.

(2) 5g of sulfomethyl phenolic resin type III, 5g of chromium-free sulfonated lignite, 8 g of the high-temperature resistant flow pattern regulator prepared in the preparation example, 2.5 g of sodium carboxymethyl starch, 28 g of a complex plugging agent and 19 g of barite are sequentially added into the mixed liquid obtained in the step (1), so that the ultrahigh-temperature-resistant low-density water-based drilling fluid S1 expected in the embodiment is obtained.

Wherein in the step, the feeding time interval of each component is 30 minutes, the stirring speed is 3000 r/min, and the preparation environment temperature is 25 ℃. The compound plugging agent is prepared from the following components in a mass ratio of 1:1 of 400 mesh calcium carbonate and 1250 mesh calcium carbonate.

Example 2

The embodiment provides an ultrahigh-temperature-resistant low-density water-based drilling fluid, which is prepared by the following steps:

(1) 100 g of tap water and 3 g of sodium bentonite are stirred for 30 minutes at the speed of 3000 rpm in the environment of 25 ℃, and then are kept stand for 24 hours for prehydration, so as to obtain a mixed solution.

(2) 4 g of sulfomethyl phenolic resin type III, 4 g of chromium-free sulfonated lignite, 7 g of the high-temperature resistant flow pattern regulator prepared in the preparation example, 2 g of sodium carboxymethyl starch, 26 g of a compound plugging agent and 18 g of barite are sequentially added into the mixed liquid obtained in the step (1), so that the ultrahigh-temperature resistant low-density water-based drilling fluid S2 expected in the embodiment is obtained.

Wherein in the step, the feeding time interval of each component is 30 minutes, the stirring speed is 3000 r/min, and the preparation environment temperature is 25 ℃. The compound plugging agent is prepared from the following components in a mass ratio of 1:2 of 400 mesh calcium carbonate and 1250 mesh calcium carbonate.

Example 3

The embodiment provides an ultrahigh-temperature-resistant low-density water-based drilling fluid, which is prepared by the following steps:

(1) 100 g of tap water and 5g of sodium bentonite are stirred for 30 minutes at the speed of 3000 rpm in the environment of 25 ℃, and then are kept stand for 24 hours for prehydration, so as to obtain a mixed solution.

(2) 6 g of sulfomethyl phenolic resin type III, 6 g of chromium-free sulfonated lignite, 9 g of the high-temperature resistant flow pattern regulator prepared in the preparation example, 3 g of sodium carboxymethyl starch, 30 g of a complex plugging agent and 20g of barite are sequentially added into the mixed liquid obtained in the step (1), so that the ultrahigh-temperature resistant low-density water-based drilling fluid S3 expected in the embodiment is obtained.

Wherein in the step, the feeding time interval of each component is 30 minutes, the stirring speed is 3000 r/min, and the preparation environment temperature is 25 ℃. The compound plugging agent is prepared from the following components in a mass ratio of 1:1.5 of a mixture of 400 mesh calcium carbonate and 1250 mesh calcium carbonate.

Example 4

Drilling fluid S4 was prepared in the same manner as in example 1, except that: the addition of bentonite was 8 grams.

Example 5

Drilling fluid S5 was prepared in the same manner as in example 1, except that: the addition amount of the sulfomethyl phenolic resin III is 8 g, the addition amount of the chromium-free sulfonated lignite is 8 g, the addition amount of the high-temperature resistant flow pattern regulator is 16 g, the addition amount of the sodium carboxymethyl starch is 4 g, the addition amount of the compound plugging agent is 45 g, and the addition amount of the barite is 28 g.

Example 6

Drilling fluid S6 was prepared in the same manner as in example 1, except that: the addition amount of the sulfomethyl phenolic resin III is 1 g, the addition amount of the chromium-free sulfonated lignite is 1 g, the addition amount of the high-temperature resistant flow pattern regulator is 2 g, the addition amount of the carboxymethyl starch is 1 g, the addition amount of the compound plugging agent is 15 g, and the addition amount of the barite is 10 g.

Comparative example 1

Drilling fluid D1 was prepared in the same manner as in example 1, except that: 8 grams of the high temperature resistant flow pattern modifier was replaced with 8 grams of acrylamide.

Comparative example 2

Drilling fluid D2 was prepared in the same manner as in example 1, except that: the dosage of the high temperature resistant flow pattern regulator is 0.5 g.

Comparative example 3

Drilling fluid D3 was prepared in the same manner as in example 1, except that: the dosage of the high temperature resistant flow pattern regulator is 30 g.

Comparative example 4

Drilling fluid D4 was prepared in the same manner as in example 1, except that: no high temperature resistant flow regulator is added.

Wherein examples 1-3 are water-based drilling fluids prepared according to preferred formulations; example 4 is a water-based drilling fluid after increasing clay content; example 5 is a simulation of a water-based drilling fluid used after increasing well depth; example 6 is a water-based drilling fluid that simulates the use of drilling fluids in shallow layers (i.e., the shallower portions of the wellbore).

Wherein, the comparative example 1 replaces the high temperature resistant flow pattern modifier prepared by the present invention with a common flow pattern modifier for comparison; comparative example 2 is a water-based drilling fluid corresponding to a very small dosage of high temperature resistant flow pattern modifier; comparative example 3 is a water-based drilling fluid corresponding to a case where the high temperature resistant flow pattern modifier is excessively added; comparative example 4 is a water-based drilling fluid corresponding to the case where no high temperature resistant flow pattern modifier was added.

See national standard "GBT 29170-.

The aging temperature of the drilling fluid is 240 ℃, the high-temperature high-pressure fluid loss performance test temperature is 240 ℃, and the rheological performance test temperature is 25 ℃ (room temperature).

The meanings of the parameters mentioned in Table 1 are indicated below:

Φ₆₀₀: viscosity (reading by viscometer 600 r/min) is unitless;

Φ₃₀₀: viscosity (reading by viscometer 300 r/min) is unitless;

AV: apparent viscosity (mPa · s);

PV: plastic viscosity (mPa · s);

YP: dynamic shear force (Pa);

YP/PV: dynamic plastic ratio (Pa/mPa · s);

HTHP loses water: high temperature high pressure water loss (mL).

TABLE 1

As can be seen from Table 1, the drilling fluids provided in examples 1 to 3 have good rheological properties, the dynamic-plastic ratios thereof are all above 0.40, which indicates that the viscosity of the drilling fluid can effectively ensure the suspension of rock debris, the high-temperature and high-pressure fluid loss thereof is all below 10 ml, and the thickness of a mud cake is 0.5 cm, which indicates that the drilling fluid system has good and coordinated rheological fluid loss properties.

The water-based drilling fluid of example 4 has an increased clay content, and it can be seen from table 1 that the rheological fluid loss properties of the water-based drilling fluid do not change much from those of example 1 although the clay content is increased, and thus it can be seen that the performance of the drilling fluid is not affected by slightly increasing the amount within the range of the soil amount defined in the present invention.

Examples 5 and 6 are water-based drilling fluids used after simulating the deepening and the shallowing of a well, namely, the addition of each component is increased/decreased along with the deepening/shallowing of the well, and as can be seen from table 1, within the components and the addition range thereof defined by the invention, the drilling fluid system can be randomly adjusted along with the change of the depth of a well bore, the rheological fluid loss performance is not greatly changed, and good performance is still maintained.

Comparative example 1 the high temperature resistant flow pattern modifier prepared by the invention was replaced with a common flow pattern modifier for comparison, as can be seen from table 1, the dynamic-plastic ratio was reduced to 0.06, which indicates that the flow pattern modifier in the drilling fluid system completely lost its effect at high temperature, so that the solid phase and liquid phase in the drilling fluid were completely separated, and the drilling fluid finally failed to effectively suspend the rock debris.

The addition amount of the high temperature resistant flow pattern modifier in comparative example 2 and comparative example 3 is not within the addition amount range defined by the present invention. As can be seen from Table 1, the viscosity of the drilling fluid is extremely low due to too little dosage of the high-temperature-resistant flow pattern regulator, the filtrate is completely lost, the viscosity of the drilling fluid is sharply increased due to too much dosage of the high-temperature-resistant flow pattern regulator, and the thickness of the mud cake is greatly increased.

The water-based drilling fluid of comparative example 4 is not added with a high temperature resistant flow pattern regulator, and the strong high temperature thickening phenomenon of the drilling fluid system can be known from table 1.

Therefore, based on the high-temperature-resistant flow pattern regulator provided by the embodiment of the invention, the quaternary ammonium groups contained in the high-temperature-resistant flow pattern regulator have positive electricity, can be adsorbed to the surfaces of the clay particles before water molecules, neutralize the electronegativity of the clay particles, and are matched with anion hydration groups, so that the clay particles are tightly coated by thick and compact hydration layers, and the flocculation tendency among the clay particles is reduced; meanwhile, the addition of each component of the drilling fluid provided by the embodiment of the invention is within the range defined by the invention, so that the drilling fluid has good rheological property and fluid loss property, and the problem of high-temperature thickening reduction of the drilling fluid is effectively solved.

The above description is only for facilitating the understanding of the technical solutions of the present invention by those skilled in the art, and is not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.