200 DEG C-resistant salt-resistant temperature-responsive cementing wall-fixing agent for water-based drilling fluid as well as preparation method and application of cementing wall-fixing agent

Abstract

The invention provides a 200 DEG C-resistant salt-resistant temperature-responsive cementing wall-fixing agent for water-based drilling fluid as well as a preparation method and application of the cementing wall-fixing agent, and belongs to the technical field of drilling. The preparation method of the cementing wall-fixing agent comprises the following steps: adding Arabic gum and an emulsifier into deionized water, and uniformly stirring to obtain a water phase; the preparation method comprises the following steps: dissolving acrylic resin and polymethyl methacrylate in dichloromethane to obtain an oil phase; adding the obtained oil phase into the obtained water phase, and carrying out shear emulsification to obtain an oil-in-water emulsion; heating and evaporating to remove the organic solvent in the emulsion to obtain a mixed solution; dropwise adding tetraethyl silicate into the mixed solution, uniformly stirring, dropwise adding 3-aminopropyltriethoxysilane into the system, and carrying out a reaction; and after the reaction is finished, filtering, washing and drying to obtain the product. According to the temperature response type cementing wall-fixing agent, the organic inner shell layer and the inorganic rigid material are adopted as the outer shell layer, so that the temperature response type cementing wall-fixing agent has a temperature response characteristic and can quickly cope with complex underground environmental conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to a 200℃ salt-resistant temperature-responsive cementing solid wall agent for water-based drilling fluid and its preparation method and application, belonging to the field of drilling technology. BACKGROUND

[0002] Wellbore instability is the most common and typical downhole complex situation, the core of which is that after the original mechanical balance of the formation is broken, the wellbore rock will be unstable, such as cracking, collapse or shrinkage, which may lead to serious consequences such as sticking, loss of circulation, and abandonment of the wellbore. At present, the action mechanism of the commonly used wellbore stabilizing material mainly includes three types: the first is hydration inhibition mechanism, which forms an adsorption film on the wellbore or adjusts the ion environment of the drilling fluid, delays the infiltration of water molecules into the formation, inhibits the hydration and dispersion of clay minerals, and prevents the wellbore from peeling off and collapsing; the second is pore plugging mechanism, which uses plugging materials of a specific particle size to fill the formation pores and microcracks, forming a dense low-permeability barrier to reduce the invasion of drilling fluid and slow down the change of formation pore pressure, thereby avoiding pressure imbalance and wellbore instability; the third is cementation strengthening mechanism, in which the treatment agent in the material reacts chemically or physically with the rock minerals to enhance the cementation between mineral particles, so that the clay minerals remain structurally intact even after long-term soaking, thereby improving the strength and stability of the wellbore.

[0003] At present, the cementing solid wall technology for water-based drilling fluid is still in its infancy. For example, Chinese patent document CN115057967A discloses a microgel solid wall agent synthesized by reverse emulsion polymerization, which has a particle size distribution of 8-50 microns. Under the action of the formation bottom hole differential pressure, it can not only physically plug the micron-sized pores and cracks of the rock, but also form an interfacial cementation with the rock through hydrogen bonding, thereby maintaining the stability of the wellbore with strong cementing strength. Chinese patent document CN106634884A prepares a biomimetic solid wall agent through free radical polymerization of polyphenol protein, acrylamide and dimethyl diallyl ammonium chloride. The core function of the biomimetic solid wall agent is to enhance the compressive strength of the core, thereby achieving wellbore stability. The design idea is inspired by the principle of biomimicry to improve the adaptability and effectiveness of the material to the rock. However, the existing preparation process mainly uses free radical polymerization as the core path, which has exposed many problems in practical application that need to be solved: first, the cementing effect is not good, it is difficult to form a uniform and high-strength cementing layer, resulting in limited wellbore strengthening effect; second, the adaptability to deep formations is poor, the cementing agent is prone to performance degradation in complex formation environments such as high temperature, high pressure and high salt, and cannot meet the needs of deep drilling; third, the compatibility with water-based drilling fluid is insufficient, which can easily cause abnormal rheological properties of the drilling fluid, such as thickening, foaming and settling, thereby interfering with normal drilling operations.

[0004] In summary, it is urgent to develop high-temperature and high-salt resistant cementing solid wall materials to effectively improve the wellbore instability problem in deep complex formations and promote the development of wellbore stability technology. Therefore, the present application is proposed. SUMMARY

[0005] In view of the defects and deficiencies in the prior art, the present application provides a 200℃ salt-resistant temperature-responsive consolidation solid wall agent for water-based drilling fluid and a preparation method and application thereof. The temperature-responsive consolidation solid wall agent of the present application wraps the acrylic resin with strong consolidation function in a small particle, which not only ensures the stability of the effective consolidation component, but also realizes accurate response and efficient effect on the well wall environment. The inorganic material on the outer shell of the particle can resist mechanical erosion and chemical corrosion during the drilling fluid circulation process, avoiding premature leakage or degradation of the acrylic resin. The organic material on the inner shell of the particle is a temperature-responsive structure. When the formation temperature rises, the inner wall swells and releases the acrylic resin core material. The resin core material can quickly penetrate into the pores and microcracks of the rock due to its good fluidity and permeability, and form a consolidation layer through self-crosslinking. At the same time, the resin core material can form hydrogen bonds or chemical bonds with active sites such as hydroxyl groups and calcium ions on the surface of the rock. In addition, the residual structure of the double shell layer can also assist in plugging the small cracks, further strengthening the consolidation strength and stability of the well wall, and avoiding the problem of solid wall failure caused by inaccurate response or insufficient protection of the single shell layer.

[0006] The technical scheme of the present application is as follows:

[0007] A preparation method of a 200℃ salt-resistant temperature-responsive consolidation solid wall agent for water-based drilling fluid, comprising the following steps:

[0008] (1) Add gum arabic and emulsifier to deionized water and stir uniformly to obtain an aqueous phase;

[0009] (2) Dissolve acrylic resin and polymethyl methacrylate in dichloromethane to obtain an oil phase;

[0010] (3) Add the oil phase obtained in step (2) to the aqueous phase obtained in step (1) and perform shear emulsification to obtain an oil-in-water emulsion; evaporate the organic solvent in the emulsion by heating to obtain a mixed solution;

[0011] (4) Add tetraethyl orthosilicate (TEOS) dropwise to the mixed solution and stir uniformly, then add 3-aminopropyltriethoxysilane dropwise to the system and perform reaction; after the reaction is completed, filter, wash and dry to obtain a 200℃ salt-resistant temperature-responsive consolidation solid wall agent for water-based drilling fluid.

[0012] According to the present application, the mass ratio of gum arabic to water in step (1) is preferably 0.03-0.1:1, and further preferably 0.04-0.06:1; the molecular weight of gum arabic is not specifically limited, and the commonly used molecular weight in the art can be used, such as gum arabic with a relative molecular mass of 100000-250000.

[0013] According to the application, preferably, the emulsifier in step (1) is sodium dodecyl sulfonate, and the mass ratio of the emulsifier to deionized water is 0.0005-0.01:1, further preferably 0.001-0.008:1.

[0014] According to the application, preferably, the acrylic resin in step (2) is a thermosetting acrylic resin, and the number average molecular weight of the acrylic resin is 10000-20000.

[0015] According to the application, preferably, the weight average molecular weight of the polymethyl methacrylate in step (2) is 800000-1200000.

[0016] According to the application, preferably, the mass ratio of the acrylic resin to polymethyl methacrylate in step (2) is 1-2:1.

[0017] According to the application, preferably, the mass ratio of the acrylic resin to dichloromethane in step (2) is 0.02-0.1:1.

[0018] According to the application, preferably, the mass ratio of dichloromethane in the oil phase to deionized water in the water phase in step (3) is 0.1-0.6:1.

[0019] According to the application, preferably, the shear emulsification in step (3) is shear emulsification using a shear emulsifier at a rotation speed of 3000-5000r / min for 5-15min.

[0020] According to the application, preferably, the temperature of the evaporation in step (3) is 40-50℃, and the time of the evaporation is 1-3h.

[0021] According to the application, preferably, the mass ratio of tetraethyl silicate (TEOS) to the total mass of the acrylic resin and polymethyl methacrylate in step (4) is 0.3-0.6:1, further preferably 0.35-0.5:1; and the dropping speed of the tetraethyl silicate (TEOS) is 0.5-1mL / min.

[0022] According to the application, preferably, the mass ratio of 3-aminopropyl triethoxysilane to tetraethyl silicate (TEOS) in step (4) is 0.01-0.04:1; and the dropping speed of the 3-aminopropyl triethoxysilane is 0.1-0.3mL / min.

[0023] According to the application, preferably, the temperature of the reaction in step (4) is 40-50℃, and the time of the reaction is 10-15h.

[0024] Preferably, in step (4), the washing is washing 3-5 times using deionized water, and the drying is drying at 40-60 DEG C for 20-30 h.

[0025] The application provides a 200 DEG C salt-resistant temperature-responsive consolidation solid wall agent for water-based drilling fluid, which is obtained by the preparation method.

[0026] According to the application, the concentration of the 200 DEG C salt-resistant temperature-responsive consolidation solid wall agent in the water-based drilling fluid is 2-5 wt%.

[0027] The technical features and beneficial effects of the application are as follows.

[0028] 1. The temperature-responsive consolidation solid wall agent is prepared by solvent evaporation and sol-gel reaction, and the preparation process is simple.

[0029] 2. The temperature-responsive consolidation solid wall agent has good stability and temperature resistance, and has good dispersibility in the drilling fluid and no influence on the rheological property of the drilling fluid.

[0030] 3. The temperature-responsive consolidation solid wall agent releases the strong cementation resin of the core material after breaking, and the acrylic resin contacts the rock particles, first forms a hydrogen bond adsorption with the hydroxyl (-OH) on the rock surface through surface wetting, and then the active groups (carboxyl -COOH, hydroxyl -OH) in the resin and the active sites (silicate mineral Si-OH, carbonate mineral Ca 2+ ) on the rock surface form chemical bonding or strong polarity, so that the cementation strength is enhanced, the rock is cemented and reinforced, and the stability of the well wall is significantly improved.

[0031] 4. The proportion of each raw material in the temperature-responsive consolidation solid wall agent and the control of the reaction conditions directly determine the cementation and solid wall capacity and rheological control performance of the solid wall agent. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The scanning electron microscope photo of the 200 DEG C salt-resistant temperature-responsive consolidation solid wall agent for water-based drilling fluid prepared in Example 1.

[0033] Figure 2 Particle size distribution chart of the anti-200℃ salt temperature responsive cementing solid wall agent for water-based drilling fluid prepared in Example 1.

[0034] Figure 3 Infrared spectrum chart of the anti-200℃ salt temperature responsive cementing solid wall agent for water-based drilling fluid prepared in Example 1. DETAILED DESCRIPTION

[0035] The application will be further described below by specific examples, but is not limited thereto.

[0036] The experimental methods described in the examples are all conventional methods, unless otherwise specified; the reagents and materials used, unless otherwise specified, can be obtained from commercial channels.

[0037] The relative molecular mass of the gum arabic used in the examples is 100000; the weight average molecular weight of the polymethyl methacrylate is 1000000.

[0038] The acrylic resin is a thermosetting acrylic resin, and the number average molecular weight is 20000.

[0039] Example 1

[0040] A preparation method of an anti-200℃ salt temperature responsive cementing solid wall agent for water-based drilling fluid, comprising the following steps:

[0041] (1) Water phase preparation: 15 g of gum arabic and 1.5 g of sodium dodecyl sulfonate are added to 300 g of deionized water, and stirred and dissolved under ultrasonic environment to obtain a water phase.

[0042] (2) Oil phase preparation: 2 g of acrylic resin and 1 g of polymethyl methacrylate are added to 30 g of dichloromethane under stirring condition, and stirred uniformly to obtain an oil phase.

[0043] (3) The oil phase obtained in step (2) is added to the water phase obtained in step (1), and then placed in a shearing emulsifier, and sheared and emulsified at a speed of 3000 r / min for 10 min to obtain an oil-in-water emulsion; evaporated at 42℃ for 2 h to remove dichloromethane, and a mixed liquid is obtained.

[0044] (4) 1.4 g of tetraethyl orthosilicate (TEOS) was slowly added dropwise into the mixed solution at a dropwise adding rate of 0.8 mL / min, and stirred uniformly; then 0.03 g of 3-aminopropyl triethoxysilane was added dropwise (at a dropwise adding rate of 0.2 mL / min) into the system to initiate the sol-gel reaction and promote the hydrolysis of TEOS, so as to form a dense silica shell; after the addition of 3-aminopropyl triethoxysilane was completed, the reaction was carried out at 45 °C for 12 h; then the system was naturally cooled to room temperature, filtered, and the obtained solid was washed with deionized water for 4 times; the obtained solid after washing was dried at 50 °C for 24 h, to obtain the water-based drilling fluid anti-200 °C salt temperature responsive consolidation solid wall agent.

[0045] The scanning electron microscope photograph of the water-based drilling fluid anti-200 °C salt temperature responsive consolidation solid wall agent obtained in the example is shown in Figure 1 , from which it can be known that the temperature responsive consolidation solid wall agent particles have good dispersibility and no agglomeration phenomenon, the particle size distribution is in the range of 25-45 microns, and the particles have a regular spherical structure, and the core-shell structure can be seen from the broken particles. Figure 1 The particle size distribution graph of the temperature responsive consolidation solid wall agent is shown in Figure 2 , from which it can be known that the median particle size of the temperature responsive consolidation solid wall agent particles is 39.75 microns. Figure 2

[0046] The infrared spectrum of the water-based drilling fluid anti-200 °C salt temperature responsive consolidation solid wall agent obtained in the example is shown in Figure 3 , from which it can be observed that there are C-H stretching vibration absorption peaks of methylene (-CH2-) and methyl (-CH3), the absorption peak of C=C bond appears at 1510 cm -1 , and the asymmetric stretching vibration of C-O-C appears at 1030 cm -1 , in addition, there is also a Si-O-Si stretching vibration absorption peak of silicon dioxide, and these absorption peaks all confirm the successful preparation of the solid wall agent.

[0047] Example 2

[0048] A preparation method of a water-based drilling fluid anti-200 °C salt temperature responsive consolidation solid wall agent, comprising the following steps:

[0049] (1) Preparation of water phase: 15 g of gum arabic and 1.5 g of sodium dodecyl sulfate were added into 300 g of deionized water, and stirred and dissolved under ultrasonic environment to obtain the water phase.

[0050] (2) Preparation of oil phase: 2 g of acrylic resin and 2 g of polymethyl methacrylate were added into 30 g of dichloromethane under stirring condition, and stirred uniformly to obtain the oil phase.

[0051] ​(3) The oil phase obtained in step (2) is added to the water phase obtained in step (1), and then placed in a shearing emulsifier, and sheared and emulsified at a speed of 3000 r / min for 10 min to obtain an oil-in-water emulsion; dichloromethane is removed by evaporation at 42°C for 2 h to obtain a mixed solution.

[0052] (4) 1.4 g of tetraethyl orthosilicate (TEOS) is slowly dropped into the mixed solution at a dropping rate of 0.8 mL / min, and stirred uniformly; then 0.03 g of 3-aminopropyl triethoxysilane is added (at a dropping rate of 0.2 mL / min) to initiate a sol-gel reaction and promote the hydrolysis of TEOS, so as to form a dense silica shell; after the addition of 3-aminopropyl triethoxysilane is completed, the reaction is carried out at 45°C for 12 h; then it is naturally cooled to room temperature, filtered, and the obtained solid is washed with deionized water for 4 times; the obtained solid after washing is dried at 50°C for 24 h to obtain a water-based drilling fluid anti-200°C salt temperature responsive cementing solid wall agent.

[0053] Example 3

[0054] A preparation method of a water-based drilling fluid anti-200°C salt temperature responsive cementing solid wall agent, comprising the following steps:

[0055] (1) Preparation of water phase: 30 g of gum arabic and 3 g of sodium dodecyl sulfate are added to 300 g of deionized water, and stirred until completely dissolved to obtain a water phase.

[0056] (2) Preparation of oil phase: 2 g of acrylic resin and 2 g of polymethyl methacrylate are added to 180 g of dichloromethane under stirring to obtain an oil phase.

[0057] (3) The oil phase obtained in step (2) is added to the water phase obtained in step (1), and then placed in a shearing emulsifier, and sheared and emulsified at a speed of 3000 r / min for 10 min to obtain an oil-in-water emulsion; dichloromethane is removed by evaporation at 42°C for 2 h to obtain a mixed solution.

[0058] (4) 1.4 g of tetraethyl orthosilicate (TEOS) is slowly dropped into the mixed solution at a dropping rate of 0.8 mL / min, and stirred uniformly; then 0.03 g of 3-aminopropyl triethoxysilane is added (at a dropping rate of 0.2 mL / min) to initiate a sol-gel reaction and promote the hydrolysis of TEOS, so as to form a dense silica shell; after the addition of 3-aminopropyl triethoxysilane is completed, the reaction is carried out at 45°C for 12 h; then it is naturally cooled to room temperature, filtered, and the obtained solid is washed with deionized water for 4 times; the obtained solid after washing is dried at 50°C for 24 h to obtain a water-based drilling fluid anti-200°C salt temperature responsive cementing solid wall agent.

[0059] Example 4

[0060] A preparation method of a 200℃ salt temperature resistant response type cementing solid wall agent for water-based drilling fluid, comprising the following steps:

[0061] (1) Water phase preparation: 9g of gum arabic and 0.15g of sodium dodecyl sulfonate were added into 300g of deionized water, and stirred until completely dissolved to obtain a water phase.

[0062] (2) Oil phase preparation: 2g of acrylic resin and 2g of polymethyl methacrylate were added into 30g of dichloromethane under stirring, and stirred uniformly to obtain an oil phase.

[0063] (3) The oil phase obtained in step (2) was added into the water phase obtained in step (1), and then placed in a shearing emulsifier, and sheared and emulsified at a speed of 3000r / min for 10min to obtain an oil-in-water emulsion; the organic solvent was removed by evaporation at 45℃ for 2h to obtain a mixed solution.

[0064] (4) 1.4g of tetraethyl silicate (TEOS) was slowly dropped into the mixed solution at a dropping rate of 0.8mL / min, and stirred uniformly; 0.014g of 3-aminopropyl triethoxysilane was added (at a dropping rate of 0.2mL / min) to initiate a sol-gel reaction, promote the hydrolysis of TEOS, and form a dense silica shell; after the addition of 3-aminopropyl triethoxysilane was completed, the reaction was carried out at 45℃ for 12h; then naturally cooled to room temperature, filtered, and the obtained solid was washed with deionized water for 4 times; the obtained solid after washing was dried at 50℃ for 24h to obtain a 200℃ salt temperature resistant response type cementing solid wall agent for water-based drilling fluid.

[0065] Example 5

[0066] A preparation method of a 200℃ salt temperature resistant response type cementing solid wall agent for water-based drilling fluid was as described in Example 1, except that 0.9g of tetraethyl silicate (TEOS) was added in step (4).

[0067] Example 6

[0068] A preparation method of a 200℃ salt temperature resistant response type cementing solid wall agent for water-based drilling fluid was as described in Example 1, except that 1.8g of tetraethyl silicate (TEOS) was added in step (4).

[0069] Comparative Example 1

[0070] A preparation method of a solid wall agent for water-based drilling fluid was as described in Example 1, except that gum arabic was not added in step (1).

[0071] Comparative Example 2

[0072] A method for preparing a wall-stabilizing agent for water-based drilling fluid is described in Example 1, except that sodium dodecyl sulfonate is not added in step (1).

[0073] Comparative Example 3

[0074] A method for preparing a wall-solidifying agent for water-based drilling fluid is described in Example 1, except that: in step (2), an equal mass of urea-formaldehyde resin is used instead of acrylic resin.

[0075] Comparative Example 4

[0076] A method for preparing a wall-stabilizing agent for water-based drilling fluid is described in Example 1, except that polymethyl methacrylate is not added in step (2).

[0077] Comparative Example 5

[0078] A method for preparing a wall-stabilizing agent for water-based drilling fluid is described in Example 1, except that 3g of polymethyl methacrylate is added in step (2).

[0079] Comparative Example 6

[0080] A method for preparing a wall-stabilizing agent for water-based drilling fluid is described in Example 1, except that 3-aminopropyltriethoxysilane is not added in step (4).

[0081] Experimental Example 1

[0082] The wall-fixing agents prepared in the examples and comparative examples were evaluated for the following performance:

[0083] 1. Effect of wall-fixing agent on the rheological properties of the base slurry before and after aging

[0084] Preparation of 4% bentonite-based slurry: Add 16g bentonite and 0.56g anhydrous sodium carbonate to 400mL of water, stir thoroughly at room temperature, seal and hydrate for 24h to obtain 4% bentonite-based slurry;

[0085] Preparation of brine drilling fluid samples: Take 400 mL of 4% bentonite-based slurry, add 12 g of the wall-stabilizing agent prepared in the examples and comparative examples and 256 g (15%) of sodium chloride, and stir at 5000 r / min for 20 min at room temperature to obtain brine drilling fluid samples; the mass of the wall-stabilizing agent in the drilling fluid sample is 3% of the volume of the bentonite-based slurry.

[0086] Drilling fluid aging: The above drilling fluid samples were placed in a roller heating furnace and aged at 200℃ for 16 hours. The rheological properties of the drilling fluid were tested according to the American Petroleum Institute (API) standard (API RP 13B-1, 2019). The results are shown in Tables 1 and 2.

[0087] Table 1. Rheological property data of drilling fluid obtained by adding the wall-solidifying agent prepared in the examples.

[0088]

[0089] Table 2. Rheological property data of drilling fluids obtained by adding wall-solidifying agents prepared in the comparative example.

[0090]

[0091] As can be seen from the test results in Tables 1 and 2, after adding the temperature-responsive cementitious wall-stabilizing agent prepared in the examples, there was no significant increase in the apparent viscosity (AV), plastic viscosity (PV), and dynamic shear force (YP) of the drilling fluid before and after aging. It also had no effect on the rheological properties of the drilling fluid base slurry, and the filtration loss (FL) was [not specified]. API The filtration efficiency is significantly reduced. In summary, the temperature-responsive cementitious wall-stabilizing agent for water-based drilling fluids prepared in this invention still exhibits excellent rheological properties and filtration loss reduction properties after aging, effectively enhancing wellbore stability.

[0092] 2. Tensile strength test of single lap joint

[0093] The strength of shale flakes bonded by temperature-responsive cementitious wall-consolidating agent was tested using a single-lap joint test. Shale flakes of 50×20×5mm were selected. After sanding the test area with sandpaper, a 3% (w / w) water solution of wall-consolidating agent was evenly applied to the single-lap joint surface of the shale flakes (water treatment served as a blank control group) and pressurized (5MPa for 10min). The flakes were then placed in an aging tank containing salt-based slurry and aged at 200℃ for 16h. The tensile strength in air was tested using a universal testing machine. The results are shown in Table 3.

[0094] Preparation of brine-based slurry: Add 16g of bentonite and 0.56g of anhydrous sodium carbonate to 400mL of water, stir thoroughly at room temperature, seal and hydrate for 24h to obtain 4% bentonite-based slurry; take 400mL of 4% bentonite-based slurry, add 256g (15%) sodium chloride, stir at 5000r / min for 20min at room temperature to obtain brine-based slurry.

[0095] Table 3 Shear strength of shale slices after treatment with different wall-stabilizing agents

[0096]

[0097] As can be seen from the experimental data in Table 3, the shale flakes coated with the temperature-responsive cementitious wall-stabilizing agent prepared in this invention exhibit significantly higher shear strength than the clean water group after immersion in a high-temperature (200℃) brine (15%) environment. This demonstrates that the temperature-responsive cementitious wall-stabilizing agent of this invention has strong wall-stabilizing ability, effectively improving the shear strength of shale, enhancing wellbore stability, and effectively reducing the occurrence of complex downhole conditions.

[0098] 3. High-temperature immersion experiment

[0099] Preparation of 4% bentonite-based slurry: Add 16g bentonite and 0.56g anhydrous sodium carbonate to 400mL of water, stir thoroughly at room temperature, seal and hydrate for 24h to obtain 4% bentonite-based slurry;

[0100] Preparation of brine drilling fluid samples: Take 400 mL of 4% bentonite-based slurry, add 12 g of the wall-solidifying agent prepared in the examples and comparative examples, and 256 g (15%) sodium chloride, and stir at 5000 r / min for 20 min at room temperature to obtain brine drilling fluid samples; the mass of the wall-solidifying agent in the drilling fluid sample is 3% of the volume of the bentonite-based slurry.

[0101] Take 30 grams of 10-mesh shale rock cuttings and place them in a molding press (D=15mm). Add 3 mL of distilled water and press for 10 minutes at 15 MPa. Remove the core. Place the core in different salt drilling fluid samples and soak at 200℃ for 16 hours. Observe the integrity of the artificial core. See Table 4.

[0102] Table 4. Integrity of artificial core samples after high-temperature immersion in different drilling fluids for 16 hours.

[0103]

[0104] As can be seen from the test results in Table 4, after adding the temperature-responsive cementing and wall-stabilizing agent prepared in the example and aging at high temperature for 16 hours, the core can maintain a stable and intact morphology. This indicates that the temperature-responsive cementing and wall-stabilizing agent of the present invention has a strong wall-stabilizing ability under high temperature and high salinity conditions, which can significantly improve the cementing force of the rock and strengthen the stability of the well wall.

[0105] In summary, the temperature-responsive cementing and wall-stabilizing agent of the present invention has excellent cementing and wall-stabilizing capabilities and high-temperature resistance, and can effectively enhance wellbore stability.

[0106] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. In addition, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be considered as the content disclosed by the present invention.

Claims

1. A method for preparing a water-based drilling fluid 200℃-resistant and salt-temperature-responsive cementing and wall-stabilizing agent, characterized in that, The steps include the following: (1) Add gum arabic and emulsifier to deionized water and stir evenly to obtain an aqueous phase; the mass ratio of gum arabic to water is 0.03-0.1:1; the emulsifier is sodium dodecyl sulfonate, and the mass ratio of emulsifier to deionized water is 0.0005-0.01:1; (2) Dissolve acrylic resin and polymethyl methacrylate in dichloromethane to obtain an oil phase; the mass ratio of acrylic resin to polymethyl methacrylate is 1-2:1, and the mass ratio of acrylic resin to dichloromethane is 0.02-0.1:

1. (3) Add the oil phase obtained in step (2) to the aqueous phase obtained in step (1) and perform shear emulsification to obtain an oil-in-water emulsion; heat up and evaporate to remove the organic solvent in the emulsion to obtain a mixture; the mass ratio of dichloromethane in the oil phase to deionized water in the aqueous phase is 0.1-0.6:

1. (4) Add tetraethyl silicate dropwise to the mixture and stir evenly. Then add 3-aminopropyltriethoxysilane dropwise to the system and react. After the reaction is completed, filter, wash and dry to obtain a water-based drilling fluid 200℃ salt temperature responsive cementing and wall-stabilizing agent. The mass ratio of tetraethyl silicate to the total mass of acrylic resin and polymethyl methacrylate is 0.3-0.6:

1. The mass ratio of 3-aminopropyltriethoxysilane to tetraethyl silicate is 0.01-0.04:

1.

2. The preparation method of the 200℃-resistant and salt-temperature-responsive cementing and wall-stabilizing agent for water-based drilling fluid according to claim 1, characterized in that, The mass ratio of gum arabic to water in step (1) is 0.04-0.06:

1.

3. The preparation method of the 200℃-resistant and salt-temperature-responsive cementitious wall-stabilizing agent for water-based drilling fluid according to claim 1, characterized in that, The mass ratio of the emulsifier to deionized water in step (1) is 0.001-0.008:

1.

4. The preparation method of the 200℃-resistant and salt-temperature-responsive cementitious wall-stabilizing agent for water-based drilling fluid according to claim 1, characterized in that, The acrylic resin mentioned in step (2) is a thermosetting acrylic resin, and the number average molecular weight of the acrylic resin is 10,000-20,000.

5. The preparation method of the 200℃-resistant and salt-temperature-responsive cementing and wall-stabilizing agent for water-based drilling fluid according to claim 1, characterized in that, The weight-average molecular weight of the polymethyl methacrylate mentioned in step (2) is 800,000-1,200,000.

6. The preparation method of the 200℃-resistant and salt-temperature-responsive cementing and wall-stabilizing agent for water-based drilling fluid according to claim 1, characterized in that, The shear emulsification in step (3) is performed by shear emulsifying for 5-15 minutes at a rotation speed of 3000-5000 r / min using a shear emulsifier; the evaporation temperature is 40-50℃ and the evaporation time is 1-3 hours.

7. The preparation method of the 200℃-resistant and salt-temperature-responsive cementing and wall-stabilizing agent for water-based drilling fluid according to claim 1, characterized in that, In step (4), the mass ratio of tetraethyl silicate to the total mass of acrylic resin and polymethyl methacrylate is 0.35-0.5:1; the dropping rate of tetraethyl silicate is 0.5-1 mL / min; and the dropping rate of 3-aminopropyltriethoxysilane is 0.1-0.3 mL / min.

8. The preparation method of the 200℃-resistant and salt-temperature-responsive cementitious wall-stabilizing agent for water-based drilling fluid according to claim 1, characterized in that, The reaction temperature in step (4) is 40-50℃, and the reaction time is 10-15h; the washing is 3-5 times with deionized water, and the drying is 20-30h at 40-60℃.

9. A water-based drilling fluid 200℃ and salt-temperature responsive cementitious wall-stabilizing agent, characterized in that, It is obtained by the preparation method described in any one of claims 1-8.

10. The application of the 200℃-resistant and salt-temperature-responsive cementitious wall-stabilizing agent for water-based drilling fluids according to claim 9 in water-based drilling fluids, characterized in that, The concentration of the water-based drilling fluid using a 200℃-resistant and salt-temperature-responsive cementing and wall-stabilizing agent is 2-5 wt%.

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