Amphiphobic blocking agent and preparation method thereof, composition for preparing water-based drilling fluid, antifriction type super-amphiphobic strong-blocking water-based drilling fluid and preparation method of antifriction type super-amphiphobic strong-blocking water-based drilling fluid

Abstract

The invention relates to the field of oil and gas resource drilling, and discloses an amphiphobic blocking agent and a preparation method thereof, a composition for preparing a water-based drilling fluid, an antifriction super-amphiphobic strong-blocking water-based drilling fluid and a preparation method thereof. The preparation method of the amphiphobic blocking agent comprises the following steps: (1) performing first mixing on hydrogen peroxide, carbon nanotubes and sulfuric acid with the concentration of more than 95 wt% to obtain a mixture I; (2) carrying out second mixing on water, ethanol, nano silicon dioxide and the mixture I to obtain a mixture II; and (3) carrying out third mixing on perfluorooctyltriethoxysilane and the mixture II, so as to obtain the amphiphobic blocking agent. The antifriction type super-amphiphobic strong-plugging water-based drilling fluid prepared by adopting the amphiphobic plugging agent provided by the invention can simultaneously have the properties of antifriction, resistance reduction and strong plugging, and provides long-term practical value and economic benefit for exploiting low-porosity and low-permeability compact periodic resources in the future.

Description

Technical Field

[0001] The invention relates to the field of oil and gas resource drilling, and in particular to an amphiphilic plugging agent and a preparation method thereof, a composition for preparing a water-based drilling fluid, a friction-reducing super amphiphilic strong plugging water-based drilling fluid and a preparation method thereof. Background Art

[0002] Tight oil and gas reservoirs have become an important battlefield for domestic oil field resource succession. During their development and drilling construction, it is difficult to control the wellbore trajectory, micro-cracks in the formation are well developed, and friction and torque are difficult to effectively control. This puts forward requirements for the temperature resistance, lubricity, sealing and inhibition of the drilling fluid.

[0003] Compared with conventional oil and gas resources, tight oil and gas reservoirs have the characteristics of strong heterogeneity and low resource grade, and conventional drilling fluid technology is difficult to achieve efficient exploitation. At present, the main drilling fluid technologies used are polymer drilling fluid and high-performance drilling fluid, etc. However, these drilling fluid systems cannot completely solve the various problems that arise during the drilling process, and it is difficult to plug micro-nano pores. Tight oil and gas reservoirs are often difficult to drill and have low production due to severe liquid absorption and friction.

[0004] Therefore, it is urgent to propose a water-based drilling fluid system that takes into account the characteristics of reducing friction and resistance as well as strong plugging, which can overcome the shortcomings of the above-mentioned existing technologies and effectively solve various problems arising in the development of tight oil and gas reservoirs.

[0005] CN103146364A discloses a highly inhibiting water-based drilling fluid, which comprises the following components in parts by weight: 100 parts of water, 0.2-4 parts of a polyamine inhibitor, 0.1-1 parts of a coating inhibitor, 10-25 parts of a hydrate inhibitor, 0.1-1 parts of a viscosity enhancer, 0.5-5 parts of a fluid loss reducer, and 0.5-3 parts of a liquid lubricant; the solution focuses on solving the inhibitory performance of the water-based drilling fluid system, and its dual-porosity plugging performance and lubrication performance are relatively poor.

[0006] CN115478450A discloses a coating, whose formula contains alkyl alkoxy silane, 1H, 1H, 2H, 2H-perfluorooctyl triethoxy silane (FAS), nano-SiO2, a cross-linking additive and at least one solvent, wherein the mass ratios of the alkyl alkoxy silane, nano-SiO2, FAS and the cross-linking additive are 20-65: 1-10: 2-10: 1-10 respectively; the hydrophobic and oleophobic coating in this scheme is not suitable for use in the field of drilling fluids, and does not have the dual-repellent plugging and friction-reducing properties of a water-based drilling fluid system. Summary of the invention

[0007] The purpose of the invention is to solve the problems of friction reduction, drag reduction and poor plugging performance of water-based drilling fluid in the prior art.

[0008] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a dual-repellent plugging agent, the method comprising:

[0009] (1) hydrogen peroxide, carbon nanotubes and sulfuric acid with a concentration greater than 95wt% are first mixed to obtain a mixture I; the mass ratio of the sulfuric acid with a concentration greater than 95wt%, the hydrogen peroxide and the carbon nanotubes is 1:3.5-4.5:2-2.8; the average diameter of the carbon nanotubes is 5-8nm, and the average length is 1-2μm; the conditions of the first mixing include: temperature of 150-170°C and time of 5-6h;

[0010] (2) performing a second mixing of water, ethanol, nano-silicon dioxide and the mixture I to obtain a mixture II;

[0011] (3) performing a third mixing of perfluorooctyl triethoxysilane and the mixture II to obtain the dual-repellent plugging agent;

[0012] The mass ratio of the water, the ethanol, the nano-silicon dioxide, the perfluorooctyltriethoxysilane and the mixture I is 1:8-12:12-18:0.2-0.7:2-8.

[0013] The second aspect of the present invention provides a dual-repellent plugging agent prepared by the method described in the first aspect.

[0014] The third aspect of the present invention provides a composition for preparing a water-based drilling fluid, the composition comprising the following components:

[0015] Water, plugging agent, lubricant, fluid loss reducer, inhibitor, coating agent, film-forming agent, wall-fixing agent, NaOH, weighting agent;

[0016] Relative to 100 parts by weight of water, the content of the plugging agent is 5-16 parts by weight, the content of the lubricant is 2-6 parts by weight, the content of the fluid loss reducer is 1-5 parts by weight, the content of the inhibitor is 4-20 parts by weight, the content of the coating agent is 0.1-1 parts by weight, the content of the film-forming agent is 1-5 parts by weight, the content of the wall-fixing agent is 5-10 parts by weight, the content of the NaOH is 0.1-1 parts by weight, and the content of the weighting agent is 0-200 parts by weight;

[0017] The plugging agent is a combination of a first plugging agent and a second plugging agent in a weight ratio of 1:0.2-2; the first plugging agent is the double-repellent plugging agent described in the second aspect, and the second plugging agent is selected from at least one of calcium carbonate and white asphalt;

[0018] The inhibitor is a combination of a polyamine inhibitor and KCl in a mass ratio of 1:0.4-7.5.

[0019] The fourth aspect of the present invention provides a method for preparing a friction-reducing super-amphiphobic strong plugging water-based drilling fluid, the method comprising: stirring and mixing a mixture containing the composition described in the third aspect.

[0020] The fifth aspect of the present invention provides a friction-reducing super-amphiphobic strong plugging water-based drilling fluid prepared by the method described in the fourth aspect.

[0021] The dual-repellent plugging agent provided by the invention has the characteristics of reversing capillary force and plugging pore throats of different sizes.

[0022] The water-based drilling fluid prepared by using the amphiphilic plugging agent provided by the present invention can take into account the performance of both friction reduction and resistance reduction and strong plugging, and can reverse the wettability of the solid surface to super amphiphilic performance, maintain the self-cleaning property of the rock surface, strengthen the stability of the reservoir well wall, and provide long-term practical value and economic benefits for the future exploitation of unconventional oil and gas resources with low porosity and low permeability;

[0023] In particular, a specific amount of the plugging agent and lubricant provided by the present invention are compounded and used, and then combined with a specific amount of water, a fluid loss reducer, an inhibitor, a coating agent, a film-forming agent, a wall-fixing agent, NaOH and a weighting agent. The prepared water-based drilling fluid has good rheology and API fluid loss, and a small high-temperature and high-pressure fluid loss. It can effectively control the entry of foreign fluids into the formation, has better plugging and fluid loss reduction performance, and is beneficial to the drilling of tight oil and gas reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a transmission electron microscope image of the dual-repellent plugging agent A1 provided by the present invention. DETAILED DESCRIPTION

[0025] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0026] As mentioned above, the first aspect of the present invention provides a method for preparing a dual-repellent plugging agent, the method comprising:

[0027] (1) hydrogen peroxide, carbon nanotubes and sulfuric acid with a concentration greater than 95wt% are first mixed to obtain a mixture I; the mass ratio of the sulfuric acid with a concentration greater than 95wt%, the hydrogen peroxide and the carbon nanotubes is 1:3.5-4.5:2-2.8; the average diameter of the carbon nanotubes is 5-8nm, and the average length is 1-2μm; the conditions of the first mixing include: temperature of 150-170°C and time of 5-6h;

[0028] (2) performing a second mixing of water, ethanol, nano-silicon dioxide and the mixture I to obtain a mixture II;

[0029] (3) performing a third mixing of perfluorooctyl triethoxysilane and the mixture II to obtain the dual-repellent plugging agent;

[0030] The mass ratio of the water, the ethanol, the nano-silicon dioxide, the perfluorooctyltriethoxysilane and the mixture I is 1:8-12:12-18:0.2-0.7:2-8.

[0031] Preferably, the second mixing conditions include: temperature of 24-26° C. and time of 0.5-1 h.

[0032] Preferably, the third mixing conditions include: temperature of 55-65° C. and time of 2-4 h.

[0033] As mentioned above, the second aspect of the present invention provides a dual-repellent plugging agent prepared by the method described in the first aspect.

[0034] As mentioned above, the third aspect of the present invention provides a composition for preparing a water-based drilling fluid, the composition comprising the following components:

[0035] Water, plugging agent, lubricant, fluid loss reducer, inhibitor, coating agent, film-forming agent, wall-fixing agent, NaOH, weighting agent;

[0036] Relative to 100 parts by weight of water, the content of the plugging agent is 5-16 parts by weight, the content of the lubricant is 2-6 parts by weight, the content of the fluid loss reducer is 1-5 parts by weight, the content of the inhibitor is 4-20 parts by weight, the content of the coating agent is 0.1-1 parts by weight, the content of the film-forming agent is 1-5 parts by weight, the content of the wall-fixing agent is 5-10 parts by weight, the content of the NaOH is 0.1-1 parts by weight, and the content of the weighting agent is 0-200 parts by weight;

[0037] The plugging agent is a combination of a first plugging agent and a second plugging agent in a weight ratio of 1:0.2-2; the first plugging agent is the double-repellent plugging agent described in the second aspect, and the second plugging agent is selected from at least one of calcium carbonate and white asphalt;

[0038] The inhibitor is a combination of a polyamine inhibitor and KCl in a mass ratio of 1:0.4-7.5.

[0039] Preferably, the polyamine inhibitor is selected from at least one of polyetheramine, acrylic acid polyamine salt, and amino polyol.

[0040] According to a preferred embodiment, the lubricant is prepared by a method comprising the following steps:

[0041] SI, carrying out a first contact mixing of oleyl alcohol, 2,3-dihydroxybenzoic acid and 2,5-dihydroxybenzoic acid to obtain material I;

[0042] SII. In the presence of a protective atmosphere, p-toluenesulfonic acid and the material I are subjected to a second contact mixing to obtain the lubricant; the conditions of the second contact mixing include: a temperature of 150-170° C. and a time of 5-6 hours;

[0043] The mass ratio of the p-toluenesulfonic acid, the oleyl alcohol, the 2,3-dihydroxybenzoic acid and the 2,5-dihydroxybenzoic acid is 1:90-110:45-55:45-55. The inventors found that under this preferred embodiment, the water-based drilling fluid obtained by the present invention has lower friction and better plugging performance.

[0044] Preferably, the conditions for the first contact mixing include: temperature of 30-40° C. and time of 0.5-1 h.

[0045] Preferably, the protective atmosphere is selected from at least one of nitrogen and helium.

[0046] More preferably, in step SII, after the second contact mixing, a static treatment is further performed to obtain a stratified product, wherein the upper layer of the stratified product is the lubricant.

[0047] Preferably, relative to 100 parts by weight of water, the content of the plugging agent is 12-16 parts by weight, the content of the lubricant is 5-6 parts by weight, the content of the fluid loss reducer is 1-1.5 parts by weight, the content of the inhibitor is 9-13 parts by weight, the content of the coating agent is 0.1-0.5 parts by weight, the content of the film-forming agent is 2-4 parts by weight, the content of the wall-fixing agent is 5-8 parts by weight, the content of NaOH is 0.1-0.4 parts by weight, and the content of the weighting agent is 0-200 parts by weight. The inventors have found that under this preferred specific embodiment, the water-based drilling fluid obtained by the present invention has better friction reduction and plugging performance.

[0048] More preferably, the plugging agent is a combination of a first plugging agent and a second plugging agent in a weight ratio of 1:0.4-0.75.

[0049] Preferably, the inhibitor is a combination of a polyamine inhibitor and KCl in a mass ratio of 1:2.5-7.5.

[0050] Preferably, the fluid loss reducer is selected from at least one of zwitterionic polymers and polyols.

[0051] More preferably, the fluid loss additive is a zwitterionic polymer.

[0052] Preferably, the coating agent is selected from at least one of polymer FA367 and xanthan gum.

[0053] Preferably, the film-forming agent is selected from at least one of the oil film temporary plugging agent CMJ-1 and a low permeability film-forming agent.

[0054] In order to enhance the bonding between clay particles and the compressive strength of rock, preferably, the wall-fixing agent is selected from at least one of the bionic wall-fixing agent GBJ-1 and chitosan wall-fixing agent.

[0055] In order to increase the density of the drilling fluid to balance the formation pressure and prevent formation collapse, preferably, the weighting agent is selected from at least one of barite, iron ore and potassium formate.

[0056] As mentioned above, the fourth aspect of the present invention provides a method for preparing a friction-reducing super-amphiphobic strong plugging water-based drilling fluid, the method comprising: stirring and mixing a mixture of the composition described in the third aspect above.

[0057] According to a preferred embodiment, the stirring and mixing step comprises:

[0058] I-1, bringing water, montmorillonite, NaOH, sodium carbonate and KCl into first contact to obtain a first product;

[0059] I-2, bringing the dual-repellent plugging agent into second contact with the first product to obtain a second product;

[0060] I-3, contacting the fluid loss reducer with the second product for a third time to obtain a third product;

[0061] I-4, contacting the polyamine inhibitor, the lubricant and the third product for the fourth time to obtain a fourth product;

[0062] I-5. The coating agent, the film-forming agent, the second plugging agent, the weighting agent and the fourth product are brought into contact with each other for the fifth time to obtain the water-based drilling fluid.

[0063] Preferably, relative to 100 parts by weight of water, the amount of montmorillonite used is 4-6 parts by weight; the amount of potassium bicarbonate used is 1.6-2.4 parts by weight.

[0064] Preferably, the first contact, the second contact, the third contact, the fourth contact and the fifth contact are each independently carried out under stirring conditions, and the conditions of the first contact, the second contact, the third contact, the fourth contact and the fifth contact each independently include: temperature of 20-40°C, stirring speed of 8000-10000rpm, and time of 0.5-1h.

[0065] As mentioned above, the fifth aspect of the present invention provides a friction-reducing super-amphiphobic strong plugging water-based drilling fluid prepared by the method described in the fourth aspect.

[0066] The present invention will be described in detail below through examples.

[0067] In the following examples, unless otherwise specified, all reagents and raw materials involved are commercially available, all reagents are analytically pure products, and ethanol is anhydrous ethanol.

[0068] In the following examples, unless otherwise specified, each part by weight represents 0.1 kg.

[0069] raw material

[0070] Sulfuric acid: concentration 98wt%;

[0071] Carbon nanotube I: 5 nm in diameter, 1 μm in length, purchased from Anhui Zesheng Technology Co., Ltd.

[0072] Carbon nanotube II: diameter 10 nm, length 3 μm, purchased from Anhui Zesheng Technology Co., Ltd.;

[0073] Nano-silicon dioxide: 30 ± 5 nm, purchased from Beijing Dongfang Yuanbo Chemical Trading Co., Ltd.;

[0074] The second plugging agent: calcium carbonate, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; white asphalt, purchased from Beijing Shida Bocheng Technology Co., Ltd.;

[0075] Fluid loss reducer: high temperature resistant zwitterionic polymer KPJ-1 and polyol DYC-1, both purchased from Beijing Shida Bocheng Technology Co., Ltd.;

[0076] Coating agent: polymer FA-367 and xanthan gum, both purchased from Rongsheng Chemical Co., Ltd.

[0077] Film-forming agent: oil film temporary plugging agent CMJ-1, low permeability film-forming agent DSC-1, both purchased from Beijing Shida Bocheng Technology Co., Ltd.;

[0078] Solidifying agent: bionic solidifying agent GBJ-1 and chitosan solidifying agent were purchased from Beijing Shida Bocheng Technology Co., Ltd.

[0079] Weighting agents: barite and potassium formate, both purchased from Beijing Xinbaohai Chemical Technology Co., Ltd.;

[0080] Inhibitor I: a combination of polyetheramine and KCl in a mass ratio of 1:2.5;

[0081] Inhibitor II: a combination of polyetheramine and KCl in a mass ratio of 1:2.0.

[0082] Preparation Example A1

[0083] This preparation example is used to illustrate that the dual-repellent plugging agent of the present invention is prepared according to the following method:

[0084] (1) mixing hydrogen peroxide, carbon nanotubes I and sulfuric acid to obtain a mixture I; the mass ratio of the sulfuric acid, the hydrogen peroxide and the carbon nanotubes I is 1:4:2.5; the conditions of the first mixing are: temperature 160° C., time 5.5 h;

[0085] (2) performing a second mixing of water, ethanol, nano-silicon dioxide and the mixture I to obtain a mixture II; the second mixing conditions are: temperature of 25° C., and time of 0.5 h;

[0086] (3) performing a third mixing of perfluorooctyl triethoxysilane and the mixture II to obtain the dual-repellent plugging agent A1;

[0087] The third mixing conditions are: temperature of 65°C and time of 3h;

[0088] The mass ratio of the water, the ethanol, the nano-silica, the perfluorooctyltriethoxysilane and the mixture I is 1:10:15:0.5:5.

[0089] The present invention also provides a transmission electron microscope image of the dual-repellent plugging agent A1, as shown in FIG. Figure 1 shown.

[0090] Preparation Example A2

[0091] This preparation example adopts a process similar to that of Preparation Example A1, except that the mass ratio of sulfuric acid, hydrogen peroxide and carbon nanotubes I in this preparation example is 1:3.8:2.3; the mass ratio of water, ethanol, nano-silica, perfluorooctyltriethoxysilane and the mixture I is 1:9.5:14.5:0.52:4.75.

[0092] The rest is the same as Preparation Example A1.

[0093] The dual-repellent plugging agent A2 was prepared.

[0094] Preparation of DA1

[0095] This preparation example adopts a process similar to that of Preparation Example A1, except that an equal mass of carbon nanotubes II is used in this preparation example to replace the carbon nanotubes I in Preparation Example A1.

[0096] The rest is the same as Preparation Example A1.

[0097] The double-thin plugging agent DA1 was prepared.

[0098] Preparation of DA2

[0099] This preparation example adopts a process similar to that of Preparation Example A1, except that an equal mass of perfluorodecyltrimethoxysilane is used in this preparation example to replace the perfluorooctyltriethoxysilane in Preparation Example A1.

[0100] The rest is the same as Preparation Example A1.

[0101] The double-thin plugging agent DA2 was prepared.

[0102] Preparation of DA3

[0103] This preparation example adopts a process similar to that of Preparation Example A1, except that the mass ratio of sulfuric acid, hydrogen peroxide and carbon nanotubes I in this preparation example is 1:3.0:1.5.

[0104] The rest is the same as Preparation Example A1.

[0105] The double-thin plugging agent DA3 was prepared.

[0106] Preparation Example B1

[0107] This preparation example is used to illustrate that the preferred lubricant of the present invention is prepared according to the following method:

[0108] SI, oleyl alcohol, 2,3-dihydroxybenzoic acid and 2,5-dihydroxybenzoic acid are first contacted and mixed to obtain material I; the conditions of the first contacted and mixed are: temperature of 40° C., time of 0.5 h;

[0109] SII, in the presence of nitrogen, p-toluenesulfonic acid and the material I are contacted and mixed for the second time and then left to stand for 30 minutes, and the upper layer of the layered product is the lubricant B1;

[0110] The second contact mixing conditions are: temperature of 165°C and time of 5.5h;

[0111] The mass ratio of the p-toluenesulfonic acid, the oleyl alcohol, the 2,3-dihydroxybenzoic acid and the 2,5-dihydroxybenzoic acid is 1:100:50:50.

[0112] Example 1

[0113] This example is used to illustrate that the friction-reducing super-amphiphobic strong plugging water-based drilling fluid of the present invention is prepared according to the formula in Table 1 and the method described below.

[0114] The method for preparing a water-based drilling fluid comprises the following steps:

[0115] I-1, bringing water, 4 parts by weight of montmorillonite, NaOH, 1.6 parts by weight of sodium carbonate and KCl into first contact to obtain a first product;

[0116] I-2, bringing the dual-repellent plugging agent into second contact with the first product to obtain a second product;

[0117] I-3, contacting the fluid loss reducer with the second product for a third time to obtain a third product;

[0118] I-4, contacting the polyamine inhibitor, the lubricant and the third product for the fourth time to obtain a fourth product;

[0119] I-5. The coating agent, the film-forming agent, the second plugging agent, the weighting agent and the fourth product are brought into contact with each other for the fifth time to obtain the water-based drilling fluid.

[0120] The conditions for the first contact, the second contact, the third contact, the fourth contact and the fifth contact are all: temperature of 25° C., stirring speed of 9000 rpm, and time of 0.5 h.

[0121] Unless otherwise specified, the remaining examples were carried out using a process similar to that of Example 1, except that the formulations used in each example were different, as shown in Table 1 (Note: the parameters not listed in Table 1 are the same as the corresponding parameters in Example 1).

[0122] Table 1

[0123]

[0124]

[0125] Example 4

[0126] This embodiment adopts a process similar to that of Embodiment 1, except that a combination of a first plugging agent and a second plugging agent with a mass ratio of 1:1.2 is used in this embodiment.

[0127] The rest are the same as in Example 1.

[0128] The waterproof coiled material S4 is prepared.

[0129] Example 5

[0130] This example is carried out using a process similar to that of Example 1, except that the inhibitor I in Example 1 is replaced by an inhibitor II of equal mass in this example.

[0131] The rest are the same as in Example 1.

[0132] The waterproof coiled material S5 is prepared.

[0133] Example 6

[0134] This embodiment is carried out using a process similar to that of Embodiment 1, except that in this embodiment, a high-efficiency anti-seizing lubricant JST (manufacturer: Jilin Jiangcheng Chemical Plant) of equal quality is used to replace the lubricant B1 in Embodiment 1.

[0135] The rest are the same as in Example 1.

[0136] The waterproof coiled material S5 is prepared.

[0137] Comparative Example 1

[0138] This comparative example adopts a process similar to that of Example 1, except that an equal mass of double-thin plugging agent DA1 is used in this comparative example to replace the double-thin plugging agent A1 in Example 1.

[0139] The rest are the same as in Example 1.

[0140] The waterproof membrane DS1 was prepared.

[0141] Comparative Example 2

[0142] This comparative example adopts a process similar to that of Example 1, except that in this comparative example, an equal mass of double-thin plugging agent DA2 is used to replace the double-thin plugging agent A1 in Example 1.

[0143] The rest are the same as in Example 1.

[0144] The waterproof membrane DS2 is prepared.

[0145] Comparative Example 3

[0146] This comparative example adopts a process similar to that of Example 1, except that an equal mass of double-thin plugging agent DA3 is used in this comparative example to replace the double-thin plugging agent A1 in Example 1.

[0147] The rest are the same as in Example 1.

[0148] The waterproof membrane DS3 was prepared.

[0149] Test Example 1

[0150] This test example is used to illustrate the basic performance of the water-based drilling fluid provided by the present invention.

[0151] This test case was conducted in accordance with the standard test method in GB / T 16783.2-2014 "Field Test of Drilling Fluids in the Petroleum and Natural Gas Industry Part 1: Water-Based Drilling Fluids". The results are shown in Table 2. The basic performance tests of the water-based drilling fluid system include:

[0152] Apparent viscosity (AV, mPa·s), plastic viscosity (AV, mPa·s), dynamic shear force (YP, Pa), API filtration loss FL of water-based drilling fluid API And high temperature and high pressure filtration loss FL HTHP ; The plastic viscosity is the plastic viscosity of the drilling fluid provided in the above example after aging at 150°C.

[0153] Table 2

[0154]

[0155]

[0156] It can be seen from the results in Table 2 that the water-based drilling fluid system provided by the present invention has better rheological properties, smaller API filtration loss and high temperature and high pressure filtration loss, and can effectively control the entry of foreign fluid into the formation; while after aging at 150°C, the viscosity of the drilling fluid of the comparative example increases, and at the same time, the API filtration loss and high temperature and high pressure filtration loss increase. This shows that the drilling fluid provided by the present invention has better plugging and filtration loss reduction performance, which is beneficial to the drilling of tight oil and gas reservoirs.

[0157] Test Example 2

[0158] This test example is used to illustrate the sand bed plugging performance of the water-based drilling fluid provided by the present invention.

[0159] After aging the water-based drilling fluid provided in the example at 120° C., the test was performed using a visual medium-pressure sand bed plugging instrument (the average particle diameter of the quartz sand used was 60 to 80 μm); the steps are as follows:

[0160] Put quartz sand into the sand filling tube, and then pour 200mL of the drilling fluid provided in the above example on the top of the quartz sand. After sealing, open the nitrogen valve to increase the pressure gauge value above the sand filling tube to 100psi, then open the valve for ventilation. After timing for 30 minutes, record the drilling fluid loss in the measuring cylinder below and the depth of the drilling fluid intrusion into the sand bed. The total depth of the sand bed used in the test is 5cm. The results are shown in Table 3.

[0161] Table 3

[0162] Sand bed penetration depth / cm Drilling fluid loss / mL Example 1 1.1 0 Example 2 1.3 0 Example 3 1.4 0 Example 4 1.7 0 Example 5 1.9 0 Example 6 2.2 0 Comparative Example 1 5.0 1.7 Comparative Example 2 5.0 2.5 Comparative Example 3 5.0 2.4

[0163] It can be seen from the results in Table 3 that the water-based drilling fluid system provided by the present invention has better plugging performance.

[0164] Test Example 3

[0165] This test example is used to illustrate the lubrication performance of the water-based drilling fluid system provided by the present invention.

[0166] After the water-based drilling fluids provided in the examples were aged at 120° C., the lubricity coefficient of the drilling fluid system was tested using an extreme pressure lubrication instrument, and the lubricity coefficient reduction rate was calculated. The test results are shown in Table 4.

[0167] The calculation formula is as follows:

[0168] R = (K0-K1) / K0×100%;

[0169] Where: R: lubrication coefficient reduction rate, %;

[0170] K0: lubricity coefficient of base slurry; the base slurry is prepared by mixing water, montmorillonite and sodium carbonate, with montmorillonite used in an amount of 4 parts by weight and sodium carbonate used in an amount of 1.6 parts by weight relative to 100 parts by weight of water; the lubricity coefficient of the base slurry is measured to be 0.58;

[0171] K1: Lubrication coefficient of drilling fluid.

[0172] Table 4

[0173] Lubrication coefficient Lubrication coefficient reduction rate / % Example 1 0.08 86.2 Example 2 0.10 82.8 Example 3 0.11 81.0 Example 4 0.13 77.6 Example 5 0.15 74.1 Example 6 0.18 69.0 Comparative Example 1 0.31 46.6 Comparative Example 2 0.37 36.2 Comparative Example 3 0.39 32.8

[0174] It can be seen from the results in Table 4 that the water-based drilling fluid system provided by the present invention has better lubrication performance. After aging at 120° C., the lubrication coefficient of the drilling fluid system is not higher than 0.18, and the lubrication coefficient reduction rate is not lower than 69.0%. The test shows that the water-based drilling fluid provided by the present invention has excellent friction reduction and drag reduction effects.

[0175] Test Example 4

[0176] This test example is used to exemplarily illustrate the super-amphiphobic performance of the friction-reducing super-amphiphobic strong plugging water-based drilling fluid system obtained in the present invention.

[0177] Surface wettability is an important property of anti-friction super-amphiphobic strong plugging water-based drilling fluid. This experiment characterizes the surface wettability of water-based drilling fluid by testing the size of the surface contact angle. First, the core is cut, ground, and polished to make a smooth core slice. The water-based drilling fluid filtrate is dripped onto the prepared core slice so that the core slice is fully covered by the solution. The core is then placed in an oven at 105°C and dried for 30 minutes before being taken out for surface contact angle measurement. This experiment was tested three times in parallel and the average value was taken. The oil phase was replaced with n-hexadecane, and the test results are shown in Table 5.

[0178] Table 5

[0179]

[0180] It can be seen from the results in Table 5 that the water-based drilling fluid system provided by the present invention has better surface wetting properties and reaches a super-amphiphobic state. At this time, the deionized water droplets and the n-hexadecane oil droplets on the core surface are both spherical, indicating that the prepared super-amphiphobic-based drilling fluid can be adsorbed on the core surface to reverse the surface wetting properties and achieve surface super-amphiphobic wetting properties.

[0181] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a dual-repellent plugging agent, characterized in that: The method includes: (1) hydrogen peroxide, carbon nanotubes and sulfuric acid with a concentration greater than 95wt% are first mixed to obtain a mixture I; the mass ratio of the sulfuric acid with a concentration greater than 95wt%, the hydrogen peroxide and the carbon nanotubes is 1:3.5-4.5:2-2.8; the average diameter of the carbon nanotubes is 5-8nm, and the average length is 1-2μm; the conditions of the first mixing include: temperature of 150-170°C and time of 5-6h; (2) performing a second mixing of water, ethanol, nano-silicon dioxide and the mixture I to obtain a mixture II; (3) performing a third mixing of perfluorooctyl triethoxysilane and the mixture II to obtain the dual-repellent plugging agent; The mass ratio of the water, the ethanol, the nano-silicon dioxide, the perfluorooctyltriethoxysilane and the mixture I is 1:8-12:12-18:0.2-0.7:2-8.

2. The method according to claim 1, characterized in that The second mixing conditions include: temperature of 24-26°C and time of 0.5-1h; And / or, the third mixing conditions include: temperature of 55-65° C. and time of 2-4 h.

3. A dual-repellent plugging agent prepared by the method according to claim 1 or 2.

4. A composition for preparing a water-based drilling fluid, characterized in that: The composition contains the following components which are stored separately or mixed together: Water, plugging agent, lubricant, fluid loss reducer, inhibitor, coating agent, film-forming agent, wall-fixing agent, NaOH, weighting agent; Relative to 100 parts by weight of water, the content of the plugging agent is 5-16 parts by weight, the content of the lubricant is 2-6 parts by weight, the content of the fluid loss reducer is 1-5 parts by weight, the content of the inhibitor is 4-20 parts by weight, the content of the coating agent is 0.1-1 parts by weight, the content of the film-forming agent is 1-5 parts by weight, the content of the wall-fixing agent is 5-10 parts by weight, the content of the NaOH is 0.1-1 parts by weight, and the content of the weighting agent is 0-200 parts by weight; The plugging agent is a combination of a first plugging agent and a second plugging agent in a weight ratio of 1:0.2-2; the first plugging agent is the double-thin plugging agent according to claim 3, and the second plugging agent is selected from at least one of calcium carbonate and white asphalt; The inhibitor is a combination of a polyamine inhibitor and KCl in a mass ratio of 1:0.4-7.

5.

5. The composition according to claim 4, characterized in that The lubricant is prepared by a method comprising the following steps: SI, carrying out a first contact mixing of oleyl alcohol, 2,3-dihydroxybenzoic acid and 2,5-dihydroxybenzoic acid to obtain material I; SII, in the presence of a protective atmosphere, contacting and mixing p-toluenesulfonic acid and the material I for a second time to obtain the lubricant; The second contact mixing conditions include: temperature of 150-170°C and time of 5-6h; The mass ratio of the p-toluenesulfonic acid, the oleyl alcohol, the 2,3-dihydroxybenzoic acid and the 2,5-dihydroxybenzoic acid is 1:90-110:45-55:45-55.

6. The composition according to claim 4 or 5, characterized in that Relative to 100 parts by weight of water, the content of the plugging agent is 12-16 parts by weight, the content of the lubricant is 5-6 parts by weight, the content of the filtration reducer is 1-1.5 parts by weight, the content of the inhibitor is 9-13 parts by weight, the content of the coating agent is 0.1-0.5 parts by weight, the content of the film-forming agent is 2-4 parts by weight, the content of the wall-fixing agent is 5-8 parts by weight, the content of NaOH is 0.1-0.4 parts by weight, and the content of the weighting agent is 0-200 parts by weight.

7. The composition according to any one of claims 4 to 6, characterized in that The plugging agent is a combination of a first plugging agent and a second plugging agent in a weight ratio of 1:0.4-0.75; And / or, the inhibitor is a combination of a polyamine inhibitor and KCl in a mass ratio of 1:2.5-7.

5.

8. The composition according to any one of claims 4 to 7, characterized in that The fluid loss reducer is selected from at least one of a zwitterionic polymer and a polyol; preferably, the fluid loss reducer is a zwitterionic polymer; And / or, the coating agent is selected from at least one of polymer FA367 and xanthan gum.

9. A method for preparing a friction-reducing super-amphiphobic strong plugging water-based drilling fluid, characterized in that: The method comprises: stirring and mixing a mixture containing the composition according to any one of claims 4 to 8.

10. A friction-reducing super-amphiphobic strong plugging water-based drilling fluid prepared by the method of claim 9.

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