Method for preparing emulsifier, compound emulsifier, self-adaptive super-amphiphobic soil-phase-free oil-based drilling fluid and application of self-adaptive super-amphiphobic soil-phase-free oil-based drilling fluid

Abstract

The invention relates to the field of oil and gas resource drilling, and discloses a method for preparing an emulsifier, a compound emulsifier, a self-adaptive super-amphiphobic soil-phase-free oil-based drilling fluid and application of the self-adaptive super-amphiphobic soil-phase-free oil-based drilling fluid. The method comprises the following steps: (1) carrying out first mixing on diethanol amine, ethanol and sodium carbonate to obtain an intermediate product; and (2) carrying out second mixing on a raw material A and the intermediate product to obtain the emulsifier, the raw material A is selected from at least one of 1-bromooctadecane, stearic acid and palmitic acid. The self-adaptive super-amphiphobic soil-phase-free oil-based drilling fluid prepared by adopting the emulsifier provided by the invention has the advantages of resisting high temperature and reducing interfacial tension in a mixed system, has a solubilizing effect, and can be suitable for drilling work of unconventional oil gas and complex structure wells.

Description

Technical Field

[0001] The invention relates to the field of oil and gas resource drilling, and in particular to a method for preparing an emulsifier, a composite emulsifier, an adaptive super-amphiphobic soil-free oil-based drilling fluid and applications thereof. Background Art

[0002] In recent years, the proportion of unconventional energy wells and wells with complex geological conditions has increased year by year, and the number of shale gas horizontal wells and deep wells and ultra-deep wells in high-steep structures in front of mountains has increased day by day; therefore, during the drilling process, higher requirements are placed on drilling fluids (for example: strong inhibition, strong lubricity, resistance to high temperature, resistance to high pollution, protection of reservoirs, etc.), especially under the current low oil price conditions, the drilling fluid is required to have "high performance, low cost", etc.

[0003] The inhibition, lubricity and anti-stuckness, temperature resistance, pollution resistance, and reservoir protection of existing water-based drilling fluid technology can no longer meet the needs of safe and efficient drilling of such wells. Oil-based drilling fluid is one of the most widely used drilling fluid systems. It has good thermal stability, lubricity, anti-collapse inhibition, reservoir protection, strong pollution resistance, wide temperature adaptability, good wellbore stability and shale inhibition, and fast mechanical drilling speed. However, the current drilling fluid system cannot completely solve the various technical problems of wellbore instability and serious well leakage in drilling in complex formations such as low temperature resistance and density upper limit, poor sealing, and developed bedding during the drilling process.

[0004] Therefore, there is an urgent need to propose a drilling fluid system that has obvious advantages in terms of wellbore stability, lubrication and anti-sticking, inhibition of shale hydration expansion and formation slurrying, and rapid drilling. This will have long-term practical value and economic benefits for the future exploitation of more complex unconventional oil and gas resources and protection of reservoirs.

[0005] CN111139044A discloses a composite emulsifier for oil-based drilling fluid, which is composed of the following raw materials in terms of mass and 100%: a primary emulsifier, 20.00%-55.00%; an auxiliary emulsifier, 4.00%-20.00%; a wetting agent, 10.00%-45.00%; a shearing agent, 1.00%-6.00%; a temperature-resistant agent, 0.10%-10.00%; and a pour point depressant, 0.10%-10.00%. The oil-based drilling fluid system proposed in this scheme does not have the characteristics of self-adaptation, super-amphiphobicity and no soil phase, and has a poor reservoir protection effect.

[0006] CN103923623A discloses an oil-based drilling fluid, comprising base oil, CaCl 2The drilling fluid comprises brine, emulsifier, fluid loss reducer, calcium hydroxide, shear enhancer, viscosity enhancer and weighting material, characterized in that it also comprises a wetting agent composed of plant pine tar and plant oleic acid. The drilling fluid comprises, by weight percentage, 1% to 3% of the wetting agent, 50% to 80% of base oil, CaCl 2 The composition comprises 5% to 10% brine, 2% to 5% emulsifier, 3% to 6% fluid loss reducer, 0.5% to 3% calcium hydroxide, 0.3% to 2% shear enhancer, 0.5% to 3% viscosity enhancer, and the balance of weighting material; the CaCl 2 The mass percentage concentration of the brine is 32%. The oil-based drilling fluid system proposed in this scheme has poor rheological properties and high drilling fluid filtration loss.

[0007] CN118222256A discloses a low-colloid oil-based drilling fluid, comprising: water-in-oil base fluid; a shear enhancer; an emulsifier; an alkalinity regulator; a plugging agent; and a weighting agent. The scheme proposes a low-colloid oil-based drilling fluid system, which has a poor reservoir protection effect. Summary of the invention

[0008] The purpose of the present invention is to solve the problems of poor temperature resistance, low upper density limit, poor plugging performance, and serious well wall instability and well leakage in the prior art of soil-free oil-based drilling fluid.

[0009] In order to achieve the above object, the first aspect of the present invention provides a method for preparing an emulsifier, the method comprising:

[0010] (1) Diethanolamine, ethanol and sodium carbonate are first mixed to obtain an intermediate product; the conditions of the first mixing include: a temperature of 60-80° C. and a time of 10-60 min.

[0011] (2) performing a second mixing of the raw material A and the intermediate product to obtain the emulsifier; the conditions of the second mixing include: a temperature of 80-100° C. and a time of 6-8 hours;

[0012] Relative to 100 parts by weight of ethanol, the amount of diethanolamine is 0.4-0.6 parts by weight, the amount of sodium carbonate is 1-3 parts by weight, and the amount of raw material A is 0.8-1.2 parts by weight;

[0013] The raw material A is selected from at least one of 1-bromooctadecane, stearic acid and palmitic acid.

[0014] The second aspect of the present invention provides a composite emulsifier, which contains a primary emulsifier and an auxiliary emulsifier in a mass ratio of 1:1.5-4.5;

[0015] The primary emulsifier is a product prepared by the method described in the first aspect, wherein the raw material A is 1-bromooctadecane;

[0016] The auxiliary emulsifier is a product prepared by the method described in the first aspect, wherein the raw material A is selected from at least one of stearic acid and palmitic acid.

[0017] The third aspect of the present invention provides an adaptive super-amphiphobic soil-free oil-based drilling fluid, which contains the following components:

[0018] Base oil, brine, plugging agent, shearing agent, composite emulsifier, plugging agent, wetting agent, lubricant, fluid loss reducer, weighting agent;

[0019] Relative to 100 parts by weight of the base oil, the content of the brine is 25-35 parts by weight, the content of the plugging agent is 2-5 parts by weight, the content of the shearing agent is 0.5-3 parts by weight, the content of the composite emulsifier is 1-5 parts by weight, the content of the plugging agent is 5-10 parts by weight, the content of the wetting agent is 1-4 parts by weight, the content of the lubricant is 0.5-2 parts by weight, the content of the fluid loss reducer is 1-5 parts by weight, and the content of the weighting agent is 0-100 parts by weight;

[0020] The composite emulsifier is the composite emulsifier described in the second aspect.

[0021] The fourth aspect of the present invention provides the use of the adaptive super-amphiphobic soil-free oil-based drilling fluid described in the third aspect in the field of oil and gas resource drilling.

[0022] The adaptive super-amphiphobic soil-free oil-based drilling fluid prepared by using the emulsifier provided by the present invention has the advantages of high temperature resistance and reduced interfacial tension in the mixed system, and has a solubilizing effect. The system can be adaptively plugged according to the size of the pore structure in the formation, reduce the amount of drilling fluid leakage, and at the same time, reverse the wettability of the rock surface, maintain the stability of the oil-based drilling fluid emulsion and the stability of the reservoir well wall, and is suitable for drilling deep / ultra-deep unconventional complex oil and gas wells.

[0023] In particular, a specific amount of the composite emulsifier, shear enhancer, fluid loss reducer and plugging agent provided by the present invention is compounded and used, and then combined with a specific amount of base oil, brine, lubricant, wetting agent, plugging agent, and optionally a weighting agent, to prepare an oil-based drilling fluid with good plugging and fluid loss reduction effect, and a small amount of high-temperature and high-pressure fluid loss; good reservoir protection performance, an average permeability recovery value of more than 84.81%, and can be applied to sensitive formations; temperature resistance>150°C, performance is better than the currently commonly used soil-phase oil-based drilling fluid system, and has the ability to be applied to high-temperature reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a real-time picture of the drilling fluid provided in Example 1 of 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 an emulsifier, the method comprising:

[0027] (1) Diethanolamine, ethanol and sodium carbonate are first mixed to obtain an intermediate product; the conditions of the first mixing include: a temperature of 60-80° C. and a time of 10-60 min.

[0028] (2) performing a second mixing of the raw material A and the intermediate product to obtain the emulsifier; the conditions of the second mixing include: a temperature of 80-100° C. and a time of 6-8 hours;

[0029] Relative to 100 parts by weight of ethanol, the amount of diethanolamine is 0.4-0.6 parts by weight, the amount of sodium carbonate is 1-3 parts by weight, and the amount of raw material A is 0.8-1.2 parts by weight;

[0030] The raw material A is selected from at least one of 1-bromooctadecane, stearic acid and palmitic acid.

[0031] Preferably, the method further comprises: after performing step (2), filtering, removing the solvent, extracting and stratifying, and recrystallizing are performed in sequence.

[0032] Preferably, the extraction and stratification operation method comprises: contacting and stirring the solution after the solvent is removed with a sodium hydroxide solution with a concentration of 4-6 wt % at 70-80° C. to obtain an upper layer of oily liquid.

[0033] In the present invention, there is no particular limitation on the operation methods of filtering, removing the solvent and recrystallizing. Those skilled in the art can carry out the operations by conventional methods in the art. The present invention will not elaborate on them one by one here, and it should not be construed as limiting the present invention.

[0034] As mentioned above, the second aspect of the present invention provides a composite emulsifier, which contains a primary emulsifier and an auxiliary emulsifier in a mass ratio of 1:1.5-4.5; the primary emulsifier is a product prepared by the method described in the first aspect, wherein the raw material A is 1-bromooctadecane;

[0035] The auxiliary emulsifier is a product prepared by the method described in the first aspect, wherein the raw material A is selected from at least one of stearic acid and palmitic acid.

[0036] Preferably, the composite emulsifier contains a primary emulsifier and an auxiliary emulsifier in a mass ratio of 1:3.2-3.6. The inventors found that under this preferred embodiment, the oil-based drilling fluid obtained by the present invention has better high temperature resistance and plugging effect.

[0037] As mentioned above, the third aspect of the present invention provides an adaptive super-amphiphobic soil-free oil-based drilling fluid, which contains the following components:

[0038] Base oil, brine, plugging agent, shearing agent, composite emulsifier, plugging agent, wetting agent, lubricant, fluid loss reducer, weighting agent;

[0039] Relative to 100 parts by weight of the base oil, the content of the brine is 25-35 parts by weight, the content of the plugging agent is 2-5 parts by weight, the content of the shearing agent is 0.5-3 parts by weight, the content of the composite emulsifier is 1-5 parts by weight, the content of the plugging agent is 5-10 parts by weight, the content of the wetting agent is 1-4 parts by weight, the content of the lubricant is 0.5-2 parts by weight, the content of the fluid loss reducer is 1-5 parts by weight, and the content of the weighting agent is 0-100 parts by weight;

[0040] The composite emulsifier is the composite emulsifier described in the second aspect above.

[0041] Preferably, the shearing agent is selected from the product obtained by reacting materials including dimer acid, diethanolamine and titanium tetrachloride.

[0042] According to a preferred embodiment, the cutting agent is prepared by a method comprising the following steps:

[0043] The dimer acid, diethanolamine and titanium tetrachloride are stirred for reaction; the stirring reaction conditions include: temperature of 130-150°C, time of 3-5h; the amount mass ratio of the dimer acid, the diethanolamine and the titanium tetrachloride is 1:0.35-0.45:0.012-0.014. The inventors found that under this preferred specific embodiment, the oil-based drilling fluid obtained by the present invention has better high temperature resistance and plugging effect.

[0044] Preferably, the fluid loss reducer is prepared by a method comprising the following steps:

[0045] SI-1, in the presence of solvent I, butyl acrylate, styrene, N-hydroxymethyl acrylamide, sodium lauryl sulfate and nonylphenol polyoxyethylene ether are stirred and mixed to obtain a mixed solution;

[0046] SI-2. In the presence of a protective gas, potassium persulfate is contacted with the mixed solution to obtain the fluid loss reducer; the contact reaction conditions include: a temperature of 65-75° C. and a time of 4-5 hours;

[0047] The mass ratio of the butyl acrylate, the styrene, the N-hydroxymethyl acrylamide, the sodium dodecyl sulfate, the nonylphenol polyoxyethylene ether and the potassium persulfate is 1: 0.38-0.42: 0.18-0.22: 0.1-0.13: 0.05-0.06: 0.006-0.008. The inventors found that under this preferred embodiment, the oil-based drilling fluid obtained by the present invention has better high temperature resistance and plugging effect.

[0048] Preferably, the solvent I is water; and the protective gas is nitrogen.

[0049] More preferably, the stirring and mixing conditions include: a stirring speed of 11000-13000 rpm, a temperature of 30-80° C., and a time of 0.5-6 h.

[0050] Preferably, the plugging agent is prepared by a method comprising the following steps:

[0051] SII-1, in the presence of solvent II, propyl methacrylate, hydroxypropyl acrylate, acrylonitrile, styrene, 1-aminoethyl-3-methylimidazolium bromide and a crosslinking agent are first contacted and mixed to obtain a mixed material;

[0052] SII-2, performing a second contact mixing with the mixed material to obtain the plugging agent; the second contact mixing conditions include: a temperature of 65-75° C. and a time of 4-6 hours;

[0053] Relative to 100 parts by weight of propyl methacrylate, the amount of hydroxypropyl acrylate is 80-120 parts by weight, the amount of acrylonitrile is 24-26 parts by weight, the amount of styrene is 12-13 parts by weight, the amount of amine-based ionic liquid is 12-13 parts by weight, the amount of cross-linking agent is 4-6 parts by weight, and the amount of ammonium persulfate is 12-13 parts by weight. The inventors found that under this preferred embodiment, the oil-based drilling fluid obtained by the present invention has better high temperature resistance and plugging effect.

[0054] Preferably, the solvent II is water.

[0055] In the present invention, there is no particular requirement for the amount of solvent I and solvent II, as long as the solute can be completely dissolved.

[0056] Preferably, in step SII-1, the first contact mixing is performed at a pH value of 7-7.5, and the conditions of the first contact mixing include: a temperature of 24-26° C. and a time of 15-25 min.

[0057] Preferably, relative to 100 parts by weight of base oil, the content of the brine is 25-35 parts by weight, the content of the plugging agent is 2-5 parts by weight, the content of the shearing agent is 0.5-3 parts by weight, the content of the composite emulsifier is 1-4.5 parts by weight, the content of the plugging agent is 5-8 parts by weight, the content of the wetting agent is 1-4 parts by weight, the content of the lubricant is 1.5-2 parts by weight, the content of the fluid loss reducer is 1-3 parts by weight, and the content of the weighting agent is 0-100 parts by weight. The inventors have found that under this preferred specific embodiment, the oil-based drilling fluid obtained by the present invention has better high temperature resistance and plugging effect.

[0058] Preferably, the lubricant is selected from at least one of a polymer alcohol lubricant, an ester lubricant and a polyester lubricant.

[0059] Preferably, the wetting agent is selected from at least one of polyvinyl alcohol and Span80.

[0060] Preferably, the brine is a calcium chloride solution with a concentration of 10-30 wt%.

[0061] Preferably, the base oil is selected from at least one of diesel, gas-to-liquid oil and white oil; more preferably white oil.

[0062] According to another preferred embodiment, the plugging agent is prepared by a method comprising the following steps:

[0063] SIII-1, a first reaction is carried out between hydrogen peroxide, carbon nanotubes and sulfuric acid with a concentration greater than 95wt% 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 conditions of the first reaction include: a temperature of 150-170°C and a time of 5-6h;

[0064] SIII-2, subjecting water, ethanol, nano-silicon dioxide and the mixture I to a second reaction to obtain a mixture II; the conditions of the second reaction include: a temperature of 24-26° C. and a time of 0.5-1 h;

[0065] SIII-3, subjecting perfluorooctyltriethoxysilane to a third reaction with the mixture II to obtain the plugging agent; the conditions of the third reaction include: a temperature of 55-65° C. and a time of 2-4 hours.

[0066] 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.

[0067] In order to meet the needs of drilling in different complex formations, in the present invention, a weighting agent of appropriate weight can be selected to obtain drilling fluids of different densities; preferably, the weighting agent is selected from at least one of barite, iron ore and calcium carbonate.

[0068] In the present invention, there is no special requirement for the preparation method of the oil-based drilling fluid. Those skilled in the art can adopt conventional methods in the art, or adopt the known addition sequence in the art to obtain a drilling fluid with good texture uniformity. The present invention will not be described in detail here, and it should not be understood as limiting the present invention.

[0069] As mentioned above, the fourth aspect of the present invention provides the use of the adaptive super-amphiphobic soil-free oil-based drilling fluid described in the third aspect in the field of oil and gas resource drilling.

[0070] The present invention will be described in detail below through examples.

[0071] In the following examples, unless otherwise specified, the reagents and raw materials involved are all commercially available products, the reagents are all analytically pure products, ethanol is anhydrous ethanol; the calcium chloride solution is measured by wet weight;

[0072] In the following examples, unless otherwise specified, each part by weight represents 0.1 kg.

[0073] raw material

[0074] Base oil: white oil, brand 5# white oil, purchased from Beijing Shida Bocheng Technology Co., Ltd.;

[0075] Brine: 30wt% calcium chloride solution;

[0076] Wetting agent: Span80, purchased from Anaiji Chemical Reagent Company;

[0077] Lubricant: Lubricant HY-1 was purchased from Shandong Deshunyuan Petroleum Technology Co., Ltd.

[0078] Weighting agent: calcium carbonate;

[0079] 1-Aminoethyl-3-methylimidazolium bromide: purchased from Shanghai Aladdin Reagent Co., Ltd.

[0080] Preparation Example A

[0081] This preparation example is used to illustrate that the primary emulsifier of the present invention is prepared according to the following method:

[0082] (1) Diethanolamine, ethanol and sodium carbonate are first mixed to obtain an intermediate product; the conditions of the first mixing are: temperature of 75° C. and time of 30 min.

[0083] (2) 1-bromooctadecane is mixed with the intermediate product for a second time, and then filtered. The filtered solution is distilled under reduced pressure to remove the solvent, and then contacted with a 5%wt% sodium hydroxide solution and stirred to obtain an upper oily liquid, and the oily liquid is recrystallized to obtain the primary emulsifier A1. The conditions of the second mixing include: temperature of 90°C and time of 7h;

[0084] Relative to 100 parts by weight of ethanol, the amount of diethanolamine used is 0.5 parts by weight, the amount of sodium carbonate used is 2 parts by weight, and the amount of 1-bromooctadecane used is 1 part by weight.

[0085] Preparation Example DA

[0086] (1) Diethanolamine, ethanol and sodium carbonate are first mixed to obtain an intermediate product; the conditions of the first mixing are: temperature of 75° C. and time of 30 min.

[0087] (2) 1-bromooctadecane is mixed with the intermediate product for a second time, and then filtered. The filtered solution is distilled under reduced pressure to remove the solvent, and then contacted with a 5%wt% sodium hydroxide solution and stirred to obtain an upper oily liquid. The oily liquid is recrystallized to obtain the primary emulsifier DA1. The conditions of the second mixing include: a temperature of 90°C and a time of 7h.

[0088] Relative to 100 parts by weight of ethanol, the amount of diethanolamine used is 0.8 parts by weight, the amount of sodium carbonate used is 3.5 parts by weight, and the amount of 1-bromooctadecane used is 0.5 parts by weight.

[0089] Preparation Example B

[0090] This preparation example is used to illustrate that the auxiliary emulsifier of the present invention is prepared according to the following method:

[0091] (1) Diethanolamine, ethanol and sodium carbonate are first mixed to obtain an intermediate product; the conditions of the first mixing are: temperature of 75° C. and time of 30 min.

[0092] (2) mixing the stearic acid and the intermediate product for a second time, and then filtering the mixture, removing the solvent from the filtered solution by vacuum distillation, and then contacting and stirring the mixture with a 5%wt% sodium hydroxide solution to obtain an upper oily liquid, and recrystallizing the oily liquid to obtain the auxiliary emulsifier B; the second mixing conditions include: a temperature of 90°C and a time of 7h;

[0093] Relative to 100 parts by weight of ethanol, the amount of diethanolamine used is 0.5 parts by weight, the amount of sodium carbonate used is 2 parts by weight, and the amount of stearic acid used is 1 part by weight.

[0094] Preparation Example C

[0095] This preparation example is used to illustrate that the cutting agent of the present invention is prepared according to the following method:

[0096] The dimer acid, diethanolamine and titanium tetrachloride are stirred to react; the shearing agent C is obtained; the stirring reaction conditions include: temperature of 140° C., time of 4 hours; the mass ratio of the dimer acid, diethanolamine and titanium tetrachloride is 1:0.4:0.013.

[0097] Preparation Example D

[0098] This preparation example is used to illustrate that the fluid loss reducer of the present invention is prepared according to the following method:

[0099] SI-1. Stir and mix butyl acrylate, styrene, N-hydroxymethyl acrylamide, sodium dodecyl sulfate and nonylphenol polyoxyethylene ether in water to obtain a mixed solution; the stirring and mixing conditions are: stirring speed of 12000 rpm, temperature of 30°C, and time of 0.5 h.

[0100] SI-2, in the presence of nitrogen, potassium persulfate is contacted with the mixed solution to obtain the fluid loss reducer D; the contact reaction conditions include: temperature of 70° C., time of 4-5 h;

[0101] The mass ratio of the butyl acrylate, the styrene, the N-hydroxymethyl acrylamide, the sodium dodecyl sulfate, the nonylphenol polyoxyethylene ether and the potassium persulfate is 1:0.4:0.2:0.12:0.06:0.008.

[0102] Preparation Example E

[0103] This preparation example is used to illustrate that the plugging agent of the present invention is prepared by the following method:

[0104] SII-1. Propyl methacrylate, hydroxypropyl acrylate, acrylonitrile, styrene, 1-aminoethyl-3-methylimidazolium bromide and a cross-linking agent are subjected to a first contact mixing in water to obtain a mixed material; the first contact mixing is carried out at a pH value of 7, and the conditions of the first contact mixing include: a temperature of 26°C and a time of 15 minutes.

[0105] SII-2, performing a second contact mixing with the mixed material to obtain the plugging agent E; the second contact mixing conditions include: a temperature of 70° C. and a time of 6 hours;

[0106] Relative to 100 parts by weight of propyl methacrylate, the amount of hydroxypropyl acrylate is 100 parts by weight, the amount of acrylonitrile is 25 parts by weight, the amount of styrene is 12.5 parts by weight, the amount of amine-based ionic liquid is 12.5 parts by weight, the amount of the cross-linking agent is 5 parts by weight, and the amount of ammonium persulfate is 12.5 parts by weight.

[0107] Preparation Example F

[0108] This preparation example is used to illustrate that the plugging agent of the present invention is prepared according to the following method:

[0109] SIII-1, hydrogen peroxide, carbon nanotubes I and sulfuric acid with a concentration of 98wt% are subjected to a first reaction 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 reaction are: temperature 160°C, time 5.5h;

[0110] SIII-2, subjecting water, ethanol, nano-silicon dioxide and the mixture I to a second reaction to obtain a mixture II; the conditions of the second reaction are: temperature of 25° C., time of 0.5 h;

[0111] SIII-3, subjecting perfluorooctyltriethoxysilane to a third reaction with the mixture II to obtain the plugging agent F;

[0112] The third mixing conditions are: temperature of 65°C and time of 3h;

[0113] The mass ratio of the water, the ethanol, the nano-silica, the perfluorooctyltriethoxysilane and the mixture I is 1:10:15:0.5:5.

[0114] Example 1

[0115] This example is used to illustrate that the adaptive super-amphiphobic soil-free oil-based drilling fluid of the present invention is prepared according to the formula in Table 1 and the method described below.

[0116] The oil-based drilling fluid is obtained by stirring a mixture containing base oil, brine, plugging agent, shearing agent, composite emulsifier, plugging agent, wetting agent, lubricant, fluid loss reducer and weighting agent; the stirring conditions are: temperature of 25°C, time of 3h, and stirring speed of 8000-12000rpm.

[0117] Illustratively, the present invention provides a real-time diagram of the oil-based drilling fluid, as shown in FIG1 .

[0118] 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).

[0119] Table 1

[0120]

[0121]

[0122] Example 5

[0123] This example is carried out using a process similar to that of Example 1, except that an oil-soluble polymer shearing agent (brand name: TQJ-II, manufactured by Beijing Shida Bocheng Technology Co., Ltd.) is used in this example to replace the shearing agent C prepared in Preparation Example C in Example 1.

[0124] The rest are the same as in Example 1.

[0125] Oil-based drilling fluid S5 was prepared.

[0126] Example 6

[0127] This example is carried out using a process similar to that of Example 1, except that in this example, a high temperature resistant fluid loss reducer (brand name GJL-1, manufacturer: Hongyun Chemical Co., Ltd.) is used to replace the fluid loss reducer D prepared in Preparation Example D in Example 1.

[0128] The rest are the same as in Example 1.

[0129] Oil-based drilling fluid S6 was prepared.

[0130] Example 7

[0131] This example is carried out using a process similar to that of Example 1, except that a plugging agent while drilling (brand name: SDL-1, manufactured by: Rongsheng Chemical Co., Ltd.) is used in this example to replace the plugging agent E prepared in Preparation Example E in Example 1.

[0132] The rest are the same as in Example 1.

[0133] Oil-based drilling fluid S7 was prepared.

[0134] Comparative Example 1

[0135] This comparative example was carried out using a process similar to that of Example 1, except that the primary emulsifier DA prepared in Preparation Example DA of equal mass was used to replace the primary emulsifier A in Example 1.

[0136] The rest are the same as in Example 1.

[0137] Oil-based drilling fluid DS1 was prepared.

[0138] Comparative Example 2

[0139] This comparative example is carried out using a process similar to that of Example 1, except that an equal mass of a high temperature resistant primary emulsifier (brand name RE-1, manufactured by Tianjin Tiancheng Tuoyuan Technology Co., Ltd.) and an equal mass of a high temperature resistant auxiliary emulsifier (brand name RE-2, manufactured by Tianjin Tiancheng Tuoyuan Technology Co., Ltd.) are used in this comparative example to replace the composite emulsifier in Example 1.

[0140] The rest are the same as in Example 1.

[0141] Oil-based drilling fluid DS2 was prepared.

[0142] Test Example 1

[0143] This test example is used to illustrate the basic performance of the oil-based drilling fluid provided by the present invention.

[0144] 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 2: Oil-Based Drilling Fluids". The results are shown in Table 2. The basic performance tests of the water-based drilling fluid system include:

[0145] Apparent viscosity (AV, mPa·s), plastic viscosity (PV, mPa·s), dynamic shear force (YP, Pa), initial cut / final cut at gel strength (10' / 10", GEL), API filtration loss FL API And high temperature and high pressure filtration loss FL HTHP , ES (emulsification voltage), where the aging temperature is 260°C.

[0146] Table 2

[0147]

[0148] Note: “--” in Table 2 means no test was performed.

[0149] It can be seen from the results in Table 2 that the drilling fluid prepared by the present invention has slightly reduced AV and PV after aging at 260°C, and has a high demulsification voltage, indicating that the rheological parameters of the present invention remain stable under the downhole high temperature condition of 260°C, and meet the rock carrying capacity of high-temperature downhole; the drilling fluid provided by the present invention also has good plugging and filtration loss reduction performance, which is beneficial to maintaining the stability of high-temperature wells and complex structure wells drilling operations; in contrast, the rheological and filtration loss performance of other oil-based drilling fluid systems are poor, and the demulsification voltage after aging is significantly reduced, which is not conducive to the drilling of complex structure wells.

[0150] Test Example 2

[0151] This test example is used to illustrate the reservoir protection performance of the oil-based drilling fluid system obtained in the example of the present invention.

[0152] This test case was carried out in accordance with the standard test method in SYT 5358-2010 “Reservoir Sensitivity Flow Experiment Evaluation Method”, and the test results are shown in Table 3.

[0153] Reservoir protection performance tests of water-based drilling fluid systems include:

[0154] The core mass before and after contamination can be obtained by weighing with a fine electronic balance, in g;

[0155] “K 0 ” refers to the original permeability of the core, measured by the high temperature and high pressure core dynamic damage evaluation system, the unit is mD;

[0156] “K 1 ” refers to the core permeability after displacement, measured by the high temperature and high pressure core dynamic damage evaluation system, and the unit is mD.

[0157] Permeability recovery value:

[0158] Table 3

[0159] formula <![CDATA[Original permeability K 0 / mD]]> <![CDATA[Gas permeability K after damage 1 / mD]]> Permeability recovery value / % S1 0.0506 0.0482 95.26 S2 0.0456 0.0427 93.64 S3 0.0385 0.0351 91.17 S4 0.0432 0.0376 87.04 S5 0.0475 0.0419 88.21 S6 0.0374 0.0320 85.56 S7 0.0395 0.0335 84.81 D1 0.0682 0.0513 75.22 D2 0.0823 0.0612 74.36

[0160] It can be seen from the results in Table 3 that the oil-based drilling fluid system provided by the present invention can restore the permeability of the reservoir core to no less than 84.81%, and the optimal value can be as high as 95.26%, and the reservoir protection effect is remarkable.

[0161] Test Example 3

[0162] This test example is used to exemplarily illustrate the super-amphiphobic performance of the adaptive super-amphiphobic soil-free oil-based drilling fluid system obtained in the present invention.

[0163] Surface wettability is an important property of super-double oleophobic drilling fluid. This experiment characterizes the surface wettability of oil-based drilling fluid by testing the size of the core surface contact angle. First, the core is cut, ground, and polished to make a flat and smooth core slice. The oil-based drilling fluid filtrate is dripped onto the prepared core slice so that the core slice is fully covered by the solution. Then the core is placed in an oven at 105°C and dried for 30 minutes and then taken out to measure the surface contact angle. This experiment is tested three times in parallel and the average value is taken. The test results are shown in Table 4.

[0164] Table 4

[0165]

[0166] It can be seen from the results in Table 4 that the adaptive super-amphiphobic-based drilling fluid system provided by the present invention can make the core surface reach a super-amphiphobic state, indicating that the prepared adaptive super-amphiphobic-based drilling fluid can reverse the wetting properties of the core surface and maintain the stability of the oil-based drilling fluid emulsion and the stability of the reservoir well wall.

[0167] 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 an emulsifier, characterized in that: The method includes: (1) performing a first mixing of diethanolamine, ethanol and sodium carbonate to obtain an intermediate product; the conditions of the first mixing include: a temperature of 60-80° C. and a time of 10-60 min; (2) performing a second mixing of the raw material A and the intermediate product to obtain the emulsifier; the conditions of the second mixing include: a temperature of 80-100° C. and a time of 6-8 hours; Relative to 100 parts by weight of ethanol, the amount of diethanolamine is 0.4-0.6 parts by weight, the amount of sodium carbonate is 1-3 parts by weight, and the amount of raw material A is 0.8-1.2 parts by weight; The raw material A is selected from at least one of 1-bromooctadecane, stearic acid and palmitic acid.

2. A composite emulsifier, characterized in that: The composite emulsifier contains a primary emulsifier and an auxiliary emulsifier in a mass ratio of 1:1.5-4.5; The primary emulsifier is a product prepared by the method according to claim 1, wherein the raw material A is 1-bromooctadecane; The auxiliary emulsifier is a product prepared by the method according to claim 1, wherein the raw material A is selected from at least one of stearic acid and palmitic acid.

3. The composite emulsifier according to claim 2, characterized in that The composite emulsifier contains a primary emulsifier and an auxiliary emulsifier in a mass ratio of 1:3.2-3.

6.

4. An adaptive super-amphiphobic soil-free oil-based drilling fluid, characterized in that: The oil-based drilling fluid contains the following components: Base oil, brine, plugging agent, shearing agent, composite emulsifier, plugging agent, wetting agent, lubricant, fluid loss reducer, weighting agent; Relative to 100 parts by weight of the base oil, the content of the brine is 25-35 parts by weight, the content of the plugging agent is 2-5 parts by weight, the content of the shearing agent is 0.5-3 parts by weight, the content of the composite emulsifier is 1-5 parts by weight, the content of the plugging agent is 5-10 parts by weight, the content of the wetting agent is 1-4 parts by weight, the content of the lubricant is 0.5-2 parts by weight, the content of the fluid loss reducer is 1-5 parts by weight, and the content of the weighting agent is 0-100 parts by weight; The composite emulsifier is the composite emulsifier according to claim 2 or 3.

5. The oil-based drilling fluid according to claim 4, characterized in that: The shearing agent is selected from the product obtained by reacting materials including dimer acid, diethanolamine and titanium tetrachloride.

6. The oil-based drilling fluid according to claim 4 or 5, characterized in that: The fluid loss reducer is prepared by a method comprising the following steps: SI-1, in the presence of solvent I, butyl acrylate, styrene, N-hydroxymethyl acrylamide, sodium lauryl sulfate and nonylphenol polyoxyethylene ether are stirred and mixed to obtain a mixed solution; SI-2. In the presence of a protective gas, potassium persulfate is contacted with the mixed solution to obtain the fluid loss reducer; the contact reaction conditions include: a temperature of 65-75° C. and a time of 4-5 hours; The mass ratio of the butyl acrylate, the styrene, the N-hydroxymethyl acrylamide, the sodium dodecyl sulfate, the nonylphenol polyoxyethylene ether and the potassium persulfate is 1: 0.38-0.42: 0.18-0.22: 0.1-0.13: 0.05-0.06: 0.006-0.

008.

7. The oil-based drilling fluid according to any one of claims 4 to 6, characterized in that: The plugging agent is prepared by a method comprising the following steps: SII-1, in the presence of solvent II, propyl methacrylate, hydroxypropyl acrylate, acrylonitrile, styrene, 1-aminoethyl-3-methylimidazolium bromide and a crosslinking agent are first contacted and mixed to obtain a mixed material; SII-2, performing a second contact mixing with the mixed material to obtain the plugging agent; the second contact mixing conditions include: a temperature of 65-75° C. and a time of 4-6 hours; Relative to 100 parts by weight of propyl methacrylate, the amount of hydroxypropyl acrylate is 80-120 parts by weight, the amount of acrylonitrile is 24-26 parts by weight, the amount of styrene is 12-13 parts by weight, the amount of amine-based ionic liquid is 12-13 parts by weight, the amount of the cross-linking agent is 4-6 parts by weight, and the amount of ammonium persulfate is 12-13 parts by weight.

8. The oil-based drilling fluid according to any one of claims 4 to 7, characterized in that: Relative to 100 parts by weight of the base oil, the content of the brine is 25-35 parts by weight, the content of the plugging agent is 2-5 parts by weight, the content of the shearing agent is 0.5-3 parts by weight, the content of the composite emulsifier is 1-4.5 parts by weight, the content of the plugging agent is 5-8 parts by weight, the content of the wetting agent is 1-4 parts by weight, the content of the lubricant is 1.5-2 parts by weight, the content of the filtration reducer is 1-3 parts by weight, and the content of the weighting agent is 0-100 parts by weight.

9. The oil-based drilling fluid according to any one of claims 4 to 8, characterized in that: The lubricant is selected from at least one of a polymer alcohol lubricant, an ester lubricant and a polyester lubricant; And / or, the brine is a calcium chloride solution with a concentration of 10-30wt%.

10. Application of the adaptive super-amphiphobic soil-free oil-based drilling fluid according to any one of claims 4 to 9 in the field of oil and gas resource drilling.

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