Water-based drilling fluid wall-fixing stabilizer as well as preparation method and application thereof

Abstract

The invention relates to the field of drilling fluid, and discloses a water-based drilling fluid wall-fixing stabilizer, which is obtained by carrying out emulsion polymerization reaction on dimethyl diallyl ammonium chloride, acrylamide, N-acryloyl dopamine, acrylic acid and vinyl trimethoxy silane. In addition, the invention also discloses a preparation method and application of the wall-fixing stabilizer. Compared with the prior art, the wall-fixing stabilizer has the advantage that the borehole wall stability and hydration inhibition performance of shale are remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil field chemicals, and relates to a water-based drilling fluid solid wall stabilizer, a preparation method and application. BACKGROUND

[0002] Mud shale is mainly composed of clay, which is composed of clay minerals with particle size less than 5 microns and fine particle viscous soil-like substances with content greater than 50%. The clay mineral refers to a layered or layer-chain hydrous silicate mineral with fixed chemical composition, which is mainly composed of silicon-oxygen tetrahedron and aluminum-oxygen octahedron stacked in the crystal C-axis direction, including montmorillonite, illite and kaolinite. The well wall instability of mud shale formation accounts for about 90% of the whole well wall instability. If the instability of mud shale formation occurs during drilling, it will cause great difficulties to drilling engineering, mainly manifested as shrinkage, collapse and sticking of drill pipe, wellbore enlargement, resistance encountered in electrical measurement, low cementing quality and the like, which seriously affects the recording of geological data, drilling speed, drilling quality and cost, and may cause delay of drilling period, drilling failure, wellbore abandonment and increase of drilling cost. With the increasing demand for oil and gas resources in China, the well wall stability of mud shale formation has been a technical bottleneck restricting the safe and efficient development of deep oil and gas resources.

[0003] The hydration phenomenon of the drilling fluid after contacting with the formation is one of the main factors leading to the instability of the well wall. The essence of the hydration of the mud shale formation after contacting with water is the swelling of the clay mineral caused by the adsorption of the clay mineral to the combined water. Effectively preventing the water in the drilling fluid from entering the formation and preventing the transmission of the wellbore pressure to the formation is the premise of stabilizing the well wall.

[0004] The mechanism of the well wall stabilizer mainly includes two kinds, the first kind is to delay the entry of water molecules into the formation to stabilize the well wall, and the second kind is to increase the mutual cementation ability between the mineral particles by the action of the treating agent and the mineral particles, so that the clay mineral is not easy to disperse after long-time soaking in the drilling fluid. Common well wall stabilizers mainly include silicates, organosilicon, polyhydric alcohols and the like, which utilize the changes of temperature, pH, salinity and the like after entering the formation or the cloud point effect to generate physical and chemical changes, form precipitates or insoluble substances, block the micro-pore and micro-cracks of the mud shale, and then achieve the purpose of plugging and cementing the well wall.

[0005] Chinese patent application CN108395529A discloses a modified resin polymer for drilling fluid solid wall stabilizer, which is made of fatty alcohol, propylene oxide, stearic acid, surfactant and azo initiator. The preparation method comprises the following steps: weighing fatty alcohol and propylene oxide, adding them into a reaction kettle to obtain a mixture; heating the mixture, adding azo initiator to carry out polymerization reaction to obtain a polymerization product; adding stearic acid and surfactant into the polymerization product to carry out condensation reaction to obtain a condensation product; and cooling the condensation product to room temperature to obtain the modified resin polymer. The modified resin polymer can resist high temperature above 180 DEG C, effectively enhances well wall stability, reduces filtration loss, avoids well wall collapse and ensures safety of drilling engineering.

[0006] Chinese patent application CN111748330A discloses a solid wall stabilizer for drilling fluid. The solid wall stabilizer for drilling fluid is prepared from the following raw materials by weight: acrylamide 10-25 parts, adhesive 10-25 parts, dimethyl diallyl ammonium chloride 10-25 parts, acrylic acid 1-5 parts, 2-acrylamide-2-methylpropane sulfonic acid 1-5 parts, chain transfer agent 1-5 parts, initiator 2-5 parts, sodium hydroxide 5-12 parts, and distilled water 80-100 parts. The solid wall stabilizer improves the strength of well wall rock by enhancing the cohesion and adhesion between rock particles, thereby improving the anti-collapse performance of the drilling fluid. Especially, the hydration force of shale during hydration expansion can be weakened or completely offset by the cohesion of the "biological shell", thereby improving the well wall stability and the adhesion performance of the solid wall stabilizer in a water environment.

[0007] However, the solid wall stabilizer in the prior art still cannot satisfy the stability performance and hydration inhibition performance of shale well wall. SUMMARY

[0008] The present application aims to provide a water-based drilling fluid solid wall stabilizer with excellent stability performance and hydration inhibition performance for shale well wall, a preparation method and application.

[0009] To achieve the above-mentioned purpose, in one aspect, the technical scheme adopted by the present application is as follows: a water-based drilling fluid solid wall stabilizer, wherein the solid wall stabilizer is prepared by the following method:

[0010] (1) Pre-emulsification: weigh dimethyl diallyl ammonium chloride (DMDACC), acrylamide (AM), N-acryloyl dopamine (DMA), acrylic acid (AA) and vinyltrimethoxysilane (VTMS) and mix the monomers; mix and stir an ethanol aqueous solution and an emulsifier, add the mixed monomers and stir to form a pre-emulsified solution;

[0011] (2) Seed emulsion preparation: adjust one-third volume of the pre-emulsion of step (1) to pH = 7.0-7.5; slowly warm up to 70-80℃ at 2℃ / min, keep stirring during the process; prepare an aqueous solution of ammonium persulfate (APS), the total weight of APS is 0.2-1.0% of the total weight of the mixed monomers; after reaching the target temperature, add half volume of the APS solution, and after the appearance of the blue phase, form a seed emulsion by keeping the temperature constant;

[0012] (3) Emulsion polymerization: add the remaining pre-emulsion and APS solution in equal time intervals, adjust the temperature to 75-85℃; add at a constant speed within 2-6h, warm up to 80-90℃, and keep the temperature constant for 1-5h;

[0013] (4) Neutralization and discharge: adjust the pH to 8-8.5 with ammonia water; cool down to room temperature, filter the emulsion with 200 mesh filter cloth, and dry.

[0014] According to the solid wall stabilizer of the present application, the weight ratio of dimethyl diallyl ammonium chloride (DMDACC), acrylamide (AM), N-acryloyl dopamine (DMA), acrylic acid (AA) and vinyl trimethoxysilane (VTMS) is (4-6):(3-5):1:(2-4):(0.2-0.8).

[0015] According to the solid wall stabilizer of the present application, the weight ratio of dimethyl diallyl ammonium chloride (DMDACC), acrylamide (AM), N-acryloyl dopamine (DMA), acrylic acid (AA) and vinyl trimethoxysilane (VTMS) is 5:4:1:3:0.5.

[0016] According to the solid wall stabilizer of the present application, the total weight of the mixed monomers is 20-40% of the pre-emulsion.

[0017] According to the solid wall stabilizer of the present application, the emulsifier is selected from a composite emulsifier consisting of SDS and OP-10.

[0018] According to the solid wall stabilizer of the present application, the weight ratio of SDS to OP-10 is 1:2.

[0019] According to the solid wall stabilizer of the present application, the total weight of the emulsifier is 1-5% of the total weight of the mixed monomers.

[0020] According to the solid wall stabilizer of the present application, the volume percentage of the aqueous ethanol solution is 10-30%.

[0021] In another aspect, the present application also provides a preparation method of a water-based drilling fluid solid wall stabilizer, which comprises the steps of (1) pre-emulsification, (2) seed emulsion preparation, (3) emulsion polymerization and (4) neutralization and discharge.

[0022] According to the preparation method, the method comprises the following steps:

[0023] (1) Pre-emulsification: weigh dimethyl diallyl ammonium chloride (DMDACC), acrylamide (AM), N-acryloyl dopamine (DMA), acrylic acid (AA) and vinyl trimethoxysilane (VTMS) and mix the monomers; mix the aqueous ethanol solution and the emulsifier under stirring, add the mixed monomers, and stir to form a pre-emulsion;

[0024] (2) Seed emulsion preparation: adjust one-third volume of the pre-emulsion in step (1) to pH = 7.0-7.5; slowly heat to 70-80℃ at a rate of 2℃ / min, and keep stirring during the process; prepare an aqueous ammonium persulfate (APS) solution, and the total weight of APS is 0.2-1.0% of the total weight of the mixed monomers; after reaching the target temperature, add half volume of the APS solution, and keep heating after the appearance of blue phase to form a seed emulsion;

[0025] (3) Emulsion polymerization: add the remaining pre-emulsion and APS solution in batches at equal intervals, and adjust the temperature to 75-85℃; drop at a constant speed within 2-6h, heat to 80-90℃, and keep heating for 1-5h;

[0026] (4) Neutralization and discharge: adjust the pH to 8-8.5 with ammonia water; cool to room temperature, filter the emulsion with a 200-mesh filter cloth, and dry.

[0027] In another aspect, the application also provides an application of the water-based drilling fluid solid wall stabilizer for improving the shale well wall stability and hydration inhibition performance.

[0028] Compared with the prior art, the water-based drilling fluid solid wall stabilizer significantly improves the shale well wall stability and hydration inhibition performance. DETAILED DESCRIPTION

[0029] It must be pointed out that, unless the context clearly dictates otherwise, as used in the specification and the appended claims, the singular forms "a", "an" and "the" can include one referent or more than one referent (i.e., one or more than one).

[0030] Unless otherwise indicated, numerical ranges in this disclosure are approximations, and thus can include values outside the stated range. The numerical ranges in this disclosure are presented exclusively in terms of being from "about" a particular value and / or to "about" another particular value. When such a range is presented, another aspect includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of the ranges are significant, and that the use of "about" with respect to any particular value is not meant to act as a disclaimer with respect to that particular value.

[0031] References in the specification and concluding claims to parts by weight, or percentages by weight, of a particular element or component in a composition or article, denote the recommended relative proportions of the element or component by weight in relation to the total weight of the composition or article.

[0032] In this disclosure, references to solutions are aqueous solutions, unless specifically indicated to the contrary, or implied by context or custom in the art; when the solute of an aqueous solution is a liquid, all fractions and percentages are by volume, and the volume percentage of a component is based on the total volume of the composition or product that includes the component; when the solute of an aqueous solution is a solid, all fractions and percentages are by weight, and the weight percentage of a component is based on the total weight of the composition or product that includes the component.

[0033] References in this disclosure to "comprising", "including", "containing", "having" and similar terms do not intentionally exclude any optional steps, device parts, or ingredients, whether or not the same are specifically disclosed or not. For the avoidance of doubt, all methods claimed through use of the term "comprising" can include one or more additional steps, device parts or ingredients, and / or substances, whether or not the same are specifically disclosed or not. In contrast, the term "consisting of excludes any component, step or procedure not specifically recited. The term "consisting of" does not exclude additional steps, device parts or ingredients that are optional, unless otherwise specifically stated. The term "or" as used in a phrase such as "A or B" can mean A, or B, or both A and B.

[0034] Furthermore, the contents of any referenced patent or non-patent literature in this disclosure are incorporated by reference in their entirety, especially with respect to definitions disclosed therein that are not inconsistent with any definitions specifically provided in this disclosure.

[0035] In the present application, parts are by weight, temperatures are in °C or at ambient, and pressure is at or near atmospheric unless otherwise designated. Room temperature means 20-30 °C. There are numerous variations and combinations of reaction conditions, e.g., component concentrations, desired solvent, solvent mixtures, temperature, pressure and other reaction ranges, as well as reagents which become known to the skilled person and can be used in the practice of the methods described herein. Only reasonable and routine experimentation will be required to optimize such process conditions.

[0036] In the present application, N-acryloyl dopamine (DMA) was synthesized according to Zhang Feng et al. (Materials Research and Application, December 2010, Vol. 4, No. 4, P712); the rest of the raw materials were obtained by commercial purchase.

[0037] The application will be further described in conjunction with specific examples, but not limited thereto.

[0038] Example 1

[0039] (1) Pre-emulsification: the monomers were weighed and mixed according to the weight ratio of DMDACC: AM: DMA: AA: VTMS = 5:4:1:3:0.5, and the total weight of the mixed monomers was 30% of the pre-emulsion. The composite emulsifier was weighed according to SDS: OP-10 = 1:2 (by weight), and the total weight of the emulsifier was 3% of the total weight of the mixed monomers. The solvent system of the pre-emulsion was selected as 20% (by volume) ethanol aqueous solution; the ethanol aqueous solution and the composite emulsifier were mixed and placed in a constant temperature magnetic stirrer for stirring for 1 h to dissolve the composite emulsifier. The weighed mixed monomers were added to the emulsifier solution, and stirred at high speed for 0.5 h to form a pre-emulsion. The pre-emulsion was required to be left for at least 30 min without layering.

[0040] (2) Seed emulsion preparation: one-third volume of the pre-emulsion of step (1) was poured into a four-necked flask, and the pH was adjusted to 7.2 using 0.3% sodium bicarbonate aqueous solution. The temperature was slowly increased to 75 °C at a rate of 2 °C / min, and stirring was maintained during the process. A 0.4% ammonium persulfate (APS) aqueous solution was prepared; the total weight of APS was 0.6% of the total weight of the mixed monomers. When the temperature reached 75 °C, half the volume of the APS aqueous solution was added, and blue phase appeared after about 25 min, and the temperature was maintained for 15 min to form a seed emulsion.

[0041] (3) Emulsion polymerization: the remaining pre-emulsion and APS solution were added in several portions at the same time interval, and the temperature was adjusted to 80 °C; the addition was completed at a constant speed within 4 h, and the temperature was increased to 85 °C and maintained for 2 h.

[0042] (4) Neutralization of the output: the emulsion is milky white with blue light, and the pH is adjusted to about 8 with ammonia water. After cooling to room temperature, the emulsion is filtered with 200 mesh filter cloth, and the solid adhered to the stirring rod and temperature sensor is washed with deionized water together with the filter residue, and dried and weighed.

[0043] The product was subjected to infrared spectrum analysis, 3450 cm -1 , 3428 cm -1 , 3215 cm -1 , 2978 cm -1 , 2932 cm -1 , 2886 cm -1 , 1742 cm -1 , 1608 cm -1 , 1526 cm -1 , 1451 cm -1 , 1410 cm -1 , 1082 cm -1 and 1013 cm -1 Absorption peaks of each functional group appeared, and the analysis results of the infrared spectrum showed that the molecular chain contained all the designed groups, which met the expected design results.

[0044] Comparative Example 1

[0045] The monomers were weighed and mixed according to the weight ratio DMDACC: AM: DMA: AA = 5:4:1:3.5, and the total weight of the mixed monomers was 30% of the pre-emulsion; the rest was the same as Example 1.

[0046] Comparative Example 2

[0047] The monomers were weighed and mixed according to the weight ratio DMDACC: AM: AA: VTMS = 5:5:3:0.5, and the total weight of the mixed monomers was 30% of the pre-emulsion; the rest was the same as Example 1.

[0048] Comparative Example 3

[0049] The monomers were weighed and mixed according to the weight ratio DMDACC: AM: AA = 5:5:3.5, and the total weight of the mixed monomers was 30% of the pre-emulsion.

[0050] The working performance of the solid wall stabilizer was evaluated by inhibiting shale debris dispersion experiment and uniaxial compressive strength experiment.

[0051] The shale debris dispersion experiment was performed by weighing the bentonite shale debris after being placed in a 2% solid wall stabilizer solution and heated at 120℃ for 16h, and then passing through a 40 mesh sieve to calculate the rolling recovery rate of the remaining shale debris.

[0052] The uniaxial compressive strength test was determined according to the national standard GB / T 23561.7-2009 Part 7, and the sample bentonite shale core was placed in 2% solid wall stabilizer solution and hot-rolled at 120°C for 16h.

[0053] The original bentonite shale core treated by hot-rolling in water according to the same method was used as a control group.

[0054] The results are shown in Table 1.

[0055]

[0056] In addition, it should be understood that, after reading the content of the present application, those skilled in the art can make various modifications, replacements, deletions, corrections or adjustments to the technical solutions of the present application, and these equivalent technical solutions also fall within the scope defined by the claims of the present application.

Claims

1. A water-based drilling fluid wall stabilizing agent, characterized by, The solid wall stabilizer is prepared according to the following method: (1) Pre-emulsification: weigh dimethyldiallylammonium chloride, acrylamide, N-acryloyl dopamine, acrylic acid and vinyltrimethoxysilane and mix the monomers; mix the aqueous ethanol solution and the emulsifier under stirring, add the mixed monomers, and stir to form a pre-emulsion; (2) Seed emulsion preparation: adjust one-third volume of the pre-emulsion of step (1) to pH = 7.0-7.5; slowly warm up to 70-80℃ at 2℃ / min, and keep stirring during the process; prepare an aqueous ammonium persulfate (APS) solution, and the total weight of APS is 0.2-1.0% of the total weight of the mixed monomers; after reaching the target temperature, add half volume of the APS solution, and keep the temperature after the appearance of blue phase to form a seed emulsion; (3) Emulsion polymerization: add the remaining pre-emulsion and APS solution in several portions at equal intervals, and adjust the temperature to 75-85℃; complete the dropwise addition at a constant speed within 2-6h, warm up to 80-90℃, and keep the temperature for 1-5h; (4) Neutralization and discharge: adjust the pH to 8-8.5 with ammonia water; cool down to room temperature, filter the emulsion with 200 mesh filter cloth, and dry.

2. The solid wall stabilizer of claim 1, wherein, The weight ratio of dimethyldiallylammonium chloride, acrylamide, N-acryloyl dopamine, acrylic acid and vinyltrimethoxysilane is (4-6):(3-5):1:(2-4):(0.2-0.8).

3. The solid wall stabilizer of claim 2, wherein, The weight ratio of dimethyldiallylammonium chloride, acrylamide, N-acryloyl dopamine, acrylic acid and vinyltrimethoxysilane is 5:4:1:3:0.

5.

4. The solid wall stabilizer of claim 1, wherein, The total weight of the mixed monomers is 20-40% of the pre-emulsion.

5. The solid wall stabilizer of claim 1, wherein, The emulsifier is selected from a composite emulsifier consisting of SDS and OP-10.

6. The solid wall stabilizer of claim 5, wherein, The weight ratio of SDS to OP-10 is 1:

2.

7. The solid wall stabilizer of claim 1, wherein, The total weight of the emulsifier is 1-5% of the total weight of the mixed monomers.

8. The solid wall stabilizer of claim 1, wherein, The volume percentage of the aqueous ethanol solution is 10-30%.

9. The preparation method of the water-based drilling fluid solid wall stabilizer according to any one of claims 1-8, comprising steps (1) pre-emulsification; (2) seed emulsion preparation; (3) emulsion polymerization and (4) neutralization and discharge.

10. Use of a water-based drilling fluid wall stabilizer according to any one of claims 1-8, characterized in that, It is used for improving the shale well wall stability and hydration inhibition performance. It is used for improving the shale well wall stability and hydration inhibition performance.

Images