Highly efficient emulsifier, low oil-water ratio low earth phase oil-based drilling fluid and preparation method thereof

Abstract

The application discloses a kind of high-efficiency emulsifier, low oil-water ratio low clay phase oil-based drilling fluid and preparation method thereof.The emulsifier of the application is formed by the reaction of olefinic acid, organic amine and alcohol ether.The oil-based drilling fluid containing the high-efficiency emulsifier is a low oil-water ratio, low clay phase oil-based drilling fluid with low organic bentonite dosage and low emulsifier dosage.Under the condition of ensuring the basic performance of the oil-based drilling fluid, the oil content, emulsifier dosage and organic clay dosage are reduced, the rheological property, emulsification stability and sedimentation stability of the oil-based drilling fluid are improved, and the oil-based drilling fluid is suitable for-25℃ condition, and the unit cost of the oil-based drilling fluid is reduced.

Description

Technical Field

[0001] This invention relates to the field of drilling fluids, specifically to a high-efficiency emulsifier, an oil-based drilling fluid, and a method for preparing the same. Background Technology

[0002] Oil-based drilling fluids are drilling fluids that use base oil as the continuous phase and exhibit certain properties similar to oils under specific conditions. They are primarily composed of oil, water, solids, and oil-soluble chemical treatment agents, with various additives to meet the performance requirements of the drilling fluid. Compared to water-based drilling fluids, oil-based drilling fluids have better temperature resistance, stronger resistance to salt and calcium contamination, better lubricity, better corrosion resistance, and are less affected by external factors.

[0003] For high temperature (260℃) and high density (2.10~2.16g / cm³) 3 The problem of barite settling in drilling fluids is common. Halliburton (see "Domestic and International Drilling Fluid Technology Progress and Related Understanding of Drilling Fluids") uses a barite with a density of 4.8 g / cm³. 3 Submicron-sized manganese tetroxide particles, replacing barite, have been successfully used in high-temperature, high-pressure clay-free oil-based drilling fluids. The operating temperature is 204℃, and the density is 2.20 g / cm³. 3 This drilling fluid can reduce the equivalent circulating density, reduce filtration loss during drilling, casing running and cementing processes, and will not cause problems that aggravate material settling.

[0004] China's Great Wall Drilling Company (authors of "New All-Oil-Based Drilling Fluid System" and "Research and Evaluation of High-Temperature and High-Density Drilling Fluid") has developed a system with a temperature resistance of 250℃ and a density of 2.6 g / cm³ by developing organic soil resistant to 150-200℃ and polymer filtration reducers as the main treatment agents. 3 This oil-based drilling fluid system possesses advantages such as strong resistance to water, salt, and contamination by poor soil. The research and performance evaluation of ultra-high temperature, high-density oil-based drilling fluids conducted by China University of Petroleum (East China) synthesized primary and secondary emulsifiers, and selected high-temperature viscosifiers, flow pattern modifiers, wetting agents, and filtration loss reducers to construct an ultra-high temperature, high-density oil-based drilling fluid formulation. It can withstand temperatures up to 220℃ and has a maximum density of 2.8 g / cm³. 3 It exhibits good rheological and suspension stability. The literature "High-Temperature, High-Density, Low-Toxicity Oil-In-Water Drilling Fluid Technology" discloses a high-temperature, high-density, low-toxicity oil-in-water drilling fluid technology. This technology uses No. 3 white oil as the continuous phase, which has strong inhibition and strong anti-pollution ability, and can solve technical problems such as water absorption and swelling of mudstone and shale in complex formations and poor lubrication and drag reduction effects.

[0005] The patent titled "A Low Oil-Water Ratio Oil-Based Drilling Fluid" (Patent No.: ZL 201711246730X) describes a low oil-water ratio drilling fluid system. The emulsifier dosage is relatively large, and the dosage of organobentonite is not described. The patent titled "An Ultra-Low Oil-Water Ratio Oil-Based Emulsified Drilling Fluid of 40:60" (Patent No.: ZL 2015104796058) describes an ultra-low oil-water ratio oil-based drilling fluid (40:60 oil-water ratio), but only specifies the 40:60 oil-water ratio case. Furthermore, the temperature resistance is only 120℃. Based on the given examples, the drilling fluid has high viscosity, making implementation difficult, and the demulsification voltage does not meet the requirements. The patent titled "A Low Oil-Water Ratio Oil-Based Drilling Fluid and Its Preparation Method" (Patent No.: ZL 2016102737967) introduces a low oil-water ratio drilling fluid system. However, this system still uses organic bentonite as the basic structural agent, making it difficult to adjust the rheological properties. This has a certain impact on the addition of solid particles such as plugging agents, and the system's temperature resistance is only 150℃. The patent titled "A Soil-Free Oil-Based Drilling Fluid" (Patent No.: ZL 2014100247413) introduces a soil-free oil-based drilling fluid system, which also has a temperature resistance of only 150℃.

[0006] The existing oil-based drilling fluids still utilize high oil-to-water ratios and clay phases as viscosity-enhancing and shear-lifting structural materials. The oil-to-water ratio in most water-in-oil drilling fluids is above 80:20, with organic bentonite content exceeding 3%, and in some systems even higher. In field applications, considering practical considerations, high oil-to-water ratio drilling fluids require the addition of large amounts of treatment agents. Excessive organic bentonite content leads to high structural strength, causing problems such as high pump pressure and high equivalent circulation density, potentially inducing well leakage. Furthermore, under high oil-to-water ratio conditions, the drill cuttings have high oil content, making environmental treatment difficult. Additionally, the system's low-temperature resistance is not described, limiting winter construction in some regions of China. In summary, high oil-to-water ratios and high organic bentonite content increase the cost of oil-based drilling fluids and make downhole complications more likely.

[0007] Research reports on low oil-water ratio drilling fluid systems exist, but these systems involve high emulsifier and organobentonite dosages, which can alter the hydrophilicity and oleophilicity of the rock surface and pores, causing damage to the reservoir. Therefore, there is an urgent need to research and develop a low oil-water ratio, low soil phase oil-based drilling fluid with low organobentonite and low emulsifier dosages, as well as its preparation method. Summary of the Invention

[0008] The purpose of this invention is to provide a high-efficiency emulsifier, a low oil-water ratio, and a low soil phase oil-based drilling fluid, and its preparation method. The oil-based drilling fluid of this invention is a low oil-water ratio, low soil phase oil-based drilling fluid with low organic bentonite content, low emulsifier content, and low soil phase content. While maintaining the basic properties of the oil-based drilling fluid, it reduces the oil content, emulsifier content, and organic bentonite content, improving the rheological properties, emulsification stability, and sedimentation stability of the oil-based drilling fluid. It is also suitable for conditions down to -25℃, reducing the unit cost of the oil-based drilling fluid.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] This invention provides a high-efficiency emulsifier, which is a single emulsifier (without distinguishing between primary and secondary emulsifiers), formed by the reaction of olefinic acid, organic amine, and alcohol ether. It has strong emulsion film strength, high emulsification efficiency, good emulsification stability, strong temperature resistance, and the characteristic of small dosage.

[0011] According to the present invention, the mass ratio of the olefinic acid, organic amine and alcohol ether is preferably (55-58):(13-18):(17-19), and more preferably 55:18:19.

[0012] According to the high-efficiency emulsifier of the present invention, preferably, the olefinic acid is C 20 -Tetraenoic acid.

[0013] According to the high-efficiency emulsifier of the present invention, preferably, the organic amine is ethyleneamine and hydroxypropyl diamine; more preferably, the mass ratio of ethyleneamine and hydroxypropyl diamine is (10-8):(8-10).

[0014] The highly efficient emulsifier according to the present invention preferably comprises diethylene glycol ether.

[0015] The high-efficiency emulsifier according to the present invention is preferably prepared by the following steps:

[0016] The olefinic acid is heated to a first temperature, and then the organic amine is added. The temperature is then raised to a second temperature to carry out the reaction.

[0017] After the reaction is complete, the temperature is lowered to the third temperature, and then sulfur trioxide is added to continue the reaction. After the reaction is complete, the alcohol ether is added to continue the reaction. After the reaction is complete, the temperature is lowered to room temperature to obtain the high-efficiency emulsifier.

[0018] In the above preparation process, preferably, the first temperature is 65-70°C.

[0019] In the above preparation process, preferably, the second temperature is 160-170°C.

[0020] In the above preparation process, preferably, the third temperature is 70-90°C.

[0021] In a preferred embodiment, the high-efficiency emulsifier is prepared by the following steps:

[0022] Under stirring conditions of 90–100 r / min, 55–58 parts by mass of C were added to the reactor. 20 -Tetraenoic acid was heated to 65-70°C, and then 10-8 parts by mass of ethyleneamine and 8-10 parts by mass of hydroxypropyl diamine were slowly added. The temperature was then raised to 160-170°C and the reaction was allowed to proceed for 6-7 hours. After the reaction was completed, the temperature was lowered to 70-90°C, and then 8-10 parts by mass of sulfur trioxide were added and the reaction was allowed to proceed for 2-2.5 hours. After the reaction was completed, 17-19 parts by mass of diethylene glycol ether were added, and the mixture was stirred for 50-70 minutes. The mixture was then cooled to room temperature to obtain a highly efficient emulsifier.

[0023] The specific description is as follows:

[0024] C 20 -Tetraenoic acid is heated to 65-70°C while stirring, according to C 20 - Add ethyleneamine and hydroxypropyl diamine in a mass ratio of -tetraenoic acid, ethyleneamine and hydroxypropyl diamine, heat to 160-170℃, react for 6-7 hours, and then obtain the enoic acid amide intermediate by amidation reaction;

[0025] The olefin amide intermediate was cooled to 70-90℃, and sulfur trioxide was added at a mass ratio of 73-76:8-10 between the olefin amide intermediate and sulfur trioxide. The reaction was carried out for 2-2.5 hours, and the olefin amide and olefin sulfonamide intermediate were obtained by sulfonation.

[0026] Add diethylene glycol ether to the intermediate products of olefin amide and olefin sulfonamide at a mass ratio of 81-83:17-19, stir for 50-70 minutes, and then cool to room temperature to obtain a high-efficiency emulsifier.

[0027] After amidation and sulfonation reactions, olefinic acids, organic amines, and alcohol ethers form multiple olefinic amide groups and sulfonamide groups, resulting in larger radii of their hydrophilic groups and stronger adsorption at the oil-water interface, leading to better emulsification stability, wettability, and high-temperature stability. Simultaneously, the emulsifier molecules form hydrogen bonds in the drilling fluid, which, through association, further enhances its high-temperature stability. Therefore, this high-efficiency emulsifier can form stable emulsion systems under low oil-water ratio conditions, exhibiting higher emulsification efficiency, while requiring lower dosages than commercially available emulsifiers, thus offering better economic benefits.

[0028] Another aspect of this invention provides a low oil-water ratio, low soil phase oil-based drilling fluid. This drilling fluid uses diesel oil as the base oil and a low-volume, high-efficiency emulsifier and less than 2% organic bentonite as the main components, formulated with an oil-water ratio of (70:30) to (85:15). This oil-based drilling fluid features a low oil-water ratio, low organic bentonite content, moderate viscosity and shear strength, strong resistance to salt and calcium contamination, strong low-temperature resistance, good anti-collapse inhibition, and low cost.

[0029] The oil-based drilling fluid according to the present invention comprises an oil phase, an aqueous phase, a high-efficiency emulsifier, a wetting agent, organic bentonite, a cutting agent, a lignite filtration loss reducer, asphalt, quicklime, and a weighting agent.

[0030] The oil-water ratio of the oil-based drilling fluid is (70:30) to (85:15); based on the total volume of the oil phase and the water phase being 100%, the amount of organic bentonite added is 1.2wt% to 2.0wt%.

[0031] According to the oil-based drilling fluid of the present invention, the oil-to-water ratio of the drilling fluid is preferably (70:30) to (80:20), more preferably (70:30) to (75:25). The amount of organic bentonite added is preferably 1.2 wt% to 1.5 wt%.

[0032] According to the oil-based drilling fluid of the present invention, preferably, based on the total volume of the oil phase and the water phase being 100%, the oil-based drilling fluid comprises:

[0033]

[0034] The amount of weighting agent added is determined according to the density requirements of the oil-based drilling fluid.

[0035] More preferably, based on the total volume of the oil phase and the water phase being 100%, the oil-based drilling fluid comprises:

[0036]

[0037]

[0038] The amount of weighting agent added is determined according to the density requirements of the oil-based drilling fluid.

[0039] In this invention, "v%" refers to volume percentage. For example, if the total volume of the oil phase and the aqueous phase is 100 mL, then "70.0v% to 85.0v% of the oil phase" means that the oil phase is 70 mL to 85 mL. In this invention, "wt%" refers to weight percentage. For example, if the total volume of the oil phase and the aqueous phase is 100 mL, then "1.2wt% to 2.0wt% of the organic bentonite" means that the organic bentonite is 1.2 g to 2.0 g.

[0040] In the oil-based drilling fluid of the present invention, preferably, the oil phase is 0# diesel oil.

[0041] In the oil-based drilling fluid according to the present invention, preferably, the aqueous phase is a salt solution, wherein the solute in the salt solution is preferably calcium chloride and / or potassium chloride. More preferably, the concentration of the salt solution is 20 wt% to 40 wt%, and even more preferably 25 wt%.

[0042] According to the oil-based drilling fluid of the present invention, the organic bentonite is a product obtained by reacting quaternary ammonium salt and sodium alkyl polyoxyethylene ether bentonite, and the main component of the quicklime is calcium oxide.

[0043] In the oil-based drilling fluid of the present invention, preferably, the cutting agent is a resin-based cutting agent, such as modified resin HSY-4 (Hubei Hanko New Technology Co., Ltd.).

[0044] In the oil-based drilling fluid according to the present invention, preferably, the filtration loss reducer comprises an organic lignite filtration loss reducer and oxidized bitumen. More preferably, the mass ratio of the organic lignite filtration loss reducer to oxidized bitumen is 1:1.

[0045] In the oil-based drilling fluid of the present invention, preferably, the wetting agent is an alkylolamide derivative wetting agent, such as the wetting agent GW-WET (China National Petroleum Corporation Great Wall Drilling Engineering Co., Ltd.).

[0046] In the oil-based drilling fluid according to the present invention, preferably, the weighting agent is barite, and the amount added is determined according to the density requirements of the oil-based drilling fluid. For example, barite is added to the oil-based drilling fluid to a density of 1.6–2.0 g / cm³. 3 .

[0047] In another aspect, the present invention provides a method for preparing an oil-based drilling fluid, the method comprising the following steps:

[0048] S1. Mix the oil phase and the high-efficiency emulsifier to obtain mixture I;

[0049] S2. Mix the mixture I, the aqueous phase, and quicklime to obtain mixture II;

[0050] S3. Mix the mixture II, organic bentonite and cutting agent to obtain mixture III;

[0051] S4. Mix the mixture III, wetting agent, filtration reducer and weighting agent to obtain the oil-based drilling fluid.

[0052] In the above preparation method, the oil phase and water are immiscible and require the addition of surfactants for treatment before mixing. High-efficiency emulsifiers are used as surfactants. Therefore, the oil phase and high-efficiency emulsifier are first mixed, and then the aqueous phase and quicklime are added to obtain a relatively stable water-in-oil emulsion system. After a stable water-in-oil emulsion system is formed, organic bentonite and a shearing agent are added to form a stable emulsion system with a certain structure. Wetting agents (surfactants) are added to this system, along with filtration loss reducers and weighting agents, etc., as solid particles. Stirring ensures the water-in-oil emulsion is uniformly dispersed to form a stable oil-based drilling fluid with specific functions.

[0053] According to the preparation method of the present invention, in step S3, the organic bentonite and the cutting agent are added in any order. For example, in some embodiments of the present invention, mixture II is first stirred and mixed with the cutting agent, and then the organic bentonite is added and stirred.

[0054] According to the preparation method of the present invention, the stirring and mixing in each of the above steps are all high-speed stirring and mixing. Preferably, the stirring and mixing time is 20 min to 30 min; the stirring speed is 8000 r / min to 12000 r / min.

[0055] The preparation method of this invention uses high-speed stirring and mixing to form a stable water-in-oil emulsion from immiscible oil and water phases under the action of a highly efficient emulsifier. The higher the stirring speed, the more beneficial it is to disperse the aqueous phase into smaller droplets, and the higher the stability of the emulsion. At the same time, high-speed stirring also facilitates the uniform dispersion of solid particles such as organobentonite, shearing agents, filtration loss reducers, and weighting agents in the emulsion, thereby forming a more stable oil-based drilling fluid system.

[0056] Low oil-to-water ratio drilling fluids typically require the addition of large amounts of emulsifiers and organobentonite to maintain a stable water-in-oil emulsion. The inventors of this invention have discovered that the low oil-to-water ratio, low soil phase oil-based drilling fluid formulation of this invention can still form a stable water-in-oil emulsion system even under conditions of low emulsifier and low organobentonite dosage, and exhibits superior rheological properties, high demulsification voltage, and lower cost.

[0057] The beneficial effects of this invention include:

[0058] 1) The high-efficiency emulsifier provided by the present invention has the characteristics of high emulsification efficiency, good emulsification stability, strong temperature resistance, and small dosage.

[0059] 2) Because the high-efficiency emulsifier used in this invention has a better emulsification effect, the emulsion is more stable under low oil-water ratio conditions and the demulsification voltage is higher. It can reduce the oil-water ratio based on the oil-water ratio used by commercially available emulsifiers, and finally achieve the beneficial effects of the oil-based drilling fluid of this invention, such as low oil-water ratio, low organic bentonite dosage, low emulsifier dosage, low solid content, good rheological properties, good emulsification stability, and good suspension stability.

[0060] 3) The demulsification voltage of the oil-based drilling fluid provided by this invention reaches over 800V, which is higher than the industry standard SY / T6615-2005 requirement for demulsification voltage of water-in-oil drilling fluid emulsifier (≥400V). The water loss at high temperature and high pressure is less than 3mL, and the system has good sealing and lubrication properties.

[0061] 4) The oil-based drilling fluid provided by this invention has a low organic bentonite content, low solid content, and relatively low structural strength, making it easier to adjust. At the same time, a high proportion of plugging agent can be added, resulting in better anti-collapse performance.

[0062] 5) The oil-based drilling fluid provided by this invention has a temperature resistance of up to 180℃ and a maximum density of 2.0 g / cm³. 3 It has a wider range of applications.

[0063] 6) The oil-based drilling fluid provided by this invention can meet the construction requirements of -25℃ in winter.

[0064] 7) The oil-based drilling fluid provided by this invention is applicable to highly deviated directional wells, unconventional oil and gas horizontal wells, drilling in complex formations, and wells with special processes. Detailed Implementation

[0065] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0066] In the following examples, the cutting agent used is modified resin HSY-4 (Hubei Hanko New Technology Co., Ltd.); the wetting agent used is GW-WET (China Petroleum Great Wall Drilling Engineering Co., Ltd.).

[0067] The water mentioned in this invention refers to tap water. Unless otherwise specified, commercially available raw materials can be used in the preparation of the following examples.

[0068] The following tests are involved in the embodiments:

[0069] (1) The density of the drilling fluid was determined using the methods and instruments specified in "GB / T 16783.2-2012 Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 2: Oil-based Drilling Fluids";

[0070] (2) The plastic viscosity, dynamic shear force, 6-revolution reading and 3-revolution reading of drilling fluid were determined by the methods and instruments specified in "GB / T 16783.2-2012 Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry Part 2 Oil-based Drilling Fluids";

[0071] (3) The demulsification voltage of the drilling fluid was determined using the methods and instruments specified in "GB / T 16783.2-2012 Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 2: Oil-based Drilling Fluids";

[0072] (4) The API filtration loss and high-temperature and high-pressure filtration loss of drilling fluid were determined using the methods and instruments specified in "GB / T 16783.2-2012 Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 2: Oil-based Drilling Fluids"; the high-temperature and high-pressure filtration loss was determined at 150℃ and 3.5MPa.

[0073] Example 1

[0074] This embodiment prepares a high-efficiency emulsifier and an oil-based drilling fluid, and evaluates the performance of the oil-based drilling fluid, including the following processes:

[0075] (1) Preparation of high-efficiency emulsifiers:

[0076] Under stirring conditions of 90–100 r / min, 55 parts by mass of C were added to the reactor. 20 -Tetraenoic acid was heated to 65°C, and then 10 parts by mass of ethyleneamine and 8 parts by mass of hydroxypropyl diamine were slowly added. The temperature was then raised to 160-170°C and the reaction was allowed to proceed for 6 hours. After the reaction was completed, the temperature was lowered to 70-90°C, and then 8 parts by mass of sulfur trioxide were added and the reaction was allowed to proceed for 2 hours. After the reaction was completed, 19 parts by mass of diethylene glycol ether were added, and the mixture was stirred for 60 minutes. Then the temperature was lowered to room temperature to obtain a high-efficiency emulsifier.

[0077] (2) Oil-based drilling fluid formulation:

[0078] Based on the total volume of the oil and water phases, the following parameters were used for calculation: 0# diesel oil: 70 wt%; CaCl2 aqueous phase with a mass fraction of 20%: 30 wt%; organic bentonite: 2 wt%; high-efficiency emulsifier prepared by (1): 3 wt% and 5 wt%; cutting agent: 1 wt%; filtration loss reducer (organic lignite filtration loss reducer and oxidized asphalt 1:1): 4.0 wt%; wetting agent: 1.0 wt%; quicklime: 2.0 wt%; barite was weighted to a density of 1.7 g / cm³. 3 Oil-based drilling fluid.

[0079] (3) Methods for preparing drilling fluid:

[0080] The above-mentioned components were mixed with 18g of emulsifier in 280mL of diesel oil and stirred at 10000r / min for 20min on a high-speed mixer. Then, 8g of quicklime was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 120mL of 30% CaCl2 aqueous phase was added and stirred at high speed for another 30min. Under high-speed stirring conditions, 8g of organo-bentonite was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 4g of shearing agent was added and stirred for another 20min. Under high-speed stirring conditions, 4g of wetting agent was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 8g of organo-lignite was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 8g of oxidized asphalt was added and stirred at high speed for another 20min. Finally, barite was added and stirred at high speed for another 30min to obtain a low oil-water ratio, low soil phase oil-based drilling fluid.

[0081] (4) Performance evaluation of drilling fluid:

[0082] Before conducting the drilling fluid aging performance test, the performance of the drilling fluid at 50℃ was first tested, and the results are shown in Table 1. Then, the drilling fluid was placed in a high-temperature aging tank and aged at 200℃ for 16 hours. After cooling to 50℃, the performance of the aging drilling fluid was tested, and the results are shown in Table 1.

[0083] Table 1. Basic properties of oil-based drilling fluid formulated with high-efficiency emulsifier in Example 1.

[0084]

[0085] As can be seen from the data in Table 1, the rheological properties of the system are better with the increase of the amount of high-efficiency emulsifier. It can be seen that the high-efficiency emulsifier can reduce the viscosity and shear of drilling fluid to a certain extent. At the same time, the emulsifier has good high-temperature stability and can withstand temperatures up to 200℃. Since only this high-efficiency emulsifier is added to the system, the emulsification efficiency is higher, the dosage is lower than that of commercial emulsifiers, and the economy is better. It also has good emulsification stability under low oil-water ratio conditions.

[0086] Example 2

[0087] This embodiment prepares an oil-based drilling fluid and evaluates its performance, including the following processes:

[0088] (1) Low-earth phase drilling fluid formulation with an oil-water ratio of 70:30:

[0089] Based on the total volume of the oil and water phases, the following parameters were used: 0# diesel oil: 70 wt%; CaCl2 aqueous phase with a mass fraction of 30%: 30 wt%; organic bentonite: 1.2 wt%; high-efficiency emulsifier prepared in Example 1: 4.5 wt%; cutting agent: 1 wt%; filtration loss reducer (organic lignite filtration loss reducer and oxidized asphalt 1:1): 5.0 wt%; wetting agent: 1.0 wt%; quicklime: 2.0 wt%; barite weighted to 1.7 g / cm³. 3 Oil-based drilling fluid.

[0090] (2) Methods for preparing drilling fluid:

[0091] The above-mentioned components were mixed with 18g of emulsifier in 280mL of diesel oil and stirred at 10000r / min for 20min on a high-speed mixer. Then, 8g of quicklime was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 120mL of 30% CaCl2 aqueous phase was added and stirred at high speed for another 30min. Under high-speed stirring conditions, 4.8g of organo-bentonite was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 4g of shearing agent was added and stirred for another 20min. Under high-speed stirring conditions, 4g of wetting agent was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 10g of organo-lignite was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 10g of oxidized asphalt was added and stirred at high speed for another 20min. Finally, barite was added and stirred at high speed for another 30min to obtain a low oil-water ratio, low soil phase oil-based drilling fluid.

[0092] (3) Performance evaluation of drilling fluid:

[0093] Before conducting the drilling fluid aging performance test, the performance of the drilling fluid at 50℃ was first tested, and the results are shown in Table 2. Then, the drilling fluid was placed in a high-temperature aging tank and aged at 150℃ for 16 hours. After cooling to 50℃, the performance of the aged drilling fluid was tested, and the results are shown in Table 2. The aged drilling fluid was then allowed to stand at -25℃ for 24 hours to evaluate its performance, and the results are shown in Table 3.

[0094] Example 3

[0095] This embodiment prepares an oil-based drilling fluid and evaluates its performance, including the following processes:

[0096] (1) Low-earth phase drilling fluid formulation with an oil-water ratio of 75:25:

[0097] Based on the total volume of the oil and water phases, the following components were used: 0# diesel oil: 75 wt%; 30% CaCl2 aqueous phase: 25 wt%; organic bentonite: 1.5 wt%; high-efficiency emulsifier prepared in Example 1: 4.0 wt%; shearing agent: 0.8 wt%; filtration loss reducer (organic lignite filtration loss reducer and oxidized asphalt 1:1): 4.5 wt%; wetting agent: 1.0 wt%; quicklime: 1.5 wt%; barite weighted to 1.7 g / cm³. 3 Oil-based drilling fluid.

[0098] (2) Methods for preparing drilling fluid:

[0099] The above-mentioned components were mixed with 16g of emulsifier in 300mL of diesel oil and stirred at 10000r / min for 20min on a high-speed mixer. Then, 6g of quicklime was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 100mL of 30% CaCl2 aqueous phase was added and stirred at high speed for another 30min. Under high-speed stirring conditions, 6.0g of organo-bentonite was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 3.2g of cutting agent was added and stirred for another 20min. Under high-speed stirring conditions, 4g of wetting agent was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 9g of organo-lignite was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 9g of oxidized asphalt was added and stirred at high speed for another 20min. Finally, barite was added and stirred at high speed for another 30min to obtain a low oil-water ratio, low soil phase oil-based drilling fluid.

[0100] (3) The performance evaluation of drilling fluid is the same as in Example 2.

[0101] Example 4

[0102] This embodiment prepares an oil-based drilling fluid and evaluates its performance, including the following processes:

[0103] (1) Low-earth phase drilling fluid formulation with an oil-water ratio of 80:20:

[0104] Based on the total volume of the oil and water phases, the following components were used: 0# diesel oil: 80 wt%; 30% CaCl2 aqueous phase: 20 wt%; organic bentonite: 1.8 wt%; high-efficiency emulsifier prepared in Example 1: 3.5 wt%; cutting agent: 0.6 wt%; filtration loss reducer (organic lignite filtration loss reducer and oxidized asphalt 1:1): 4.0 wt%; wetting agent: 0.8 wt%; quicklime: 1.2 wt%; barite weighted to 1.7 g / cm³. 3 Oil-based drilling fluid.

[0105] (2) Methods for preparing drilling fluid:

[0106] The above-mentioned components were mixed with 14g of emulsifier in 320mL of diesel oil and stirred at 10000r / min for 20min on a high-speed mixer. Then, 4.8g of quicklime was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 80mL of 30% CaCl2 aqueous phase was added and stirred at high speed for another 30min. Under high-speed stirring conditions, 7.2g of organo-bentonite was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 2.4g of shearing agent was added and stirred for another 20min. Under high-speed stirring conditions, 3.2g of wetting agent was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 8g of organo-lignite was added and stirred at high speed for another 20min. Under high-speed stirring conditions, 8g of oxidized asphalt was added and stirred at high speed for another 20min. Finally, barite was added and stirred at high speed for another 30min to obtain a low oil-water ratio, low soil phase oil-based drilling fluid.

[0107] (3) The performance evaluation of drilling fluid is the same as in Example 2.

[0108] Example 5

[0109] This embodiment prepares an oil-based drilling fluid and evaluates its performance, including the following processes:

[0110] (1) Low-earth phase drilling fluid formulation with an oil-water ratio of 85:15:

[0111] Based on the total volume of the oil and water phases, the following components were used: 0# diesel oil: 85 wt%; 30% CaCl2 aqueous phase: 15 wt%; organic bentonite: 2.0 wt%; high-efficiency emulsifier prepared in Example 1: 3.0 wt%; shearing agent: 0.5 wt%; filtration loss reducer (organic lignite filtration loss reducer and oxidized asphalt 1:1): 4.0 wt%; wetting agent: 0.6 wt%; quicklime: 1.0 wt%; barite weighted to 1.7 g / cm³. 3 Oil-based drilling fluid.

[0112] (2) Methods for preparing drilling fluid:

[0113] The above-mentioned components were mixed with 12g of emulsifier in 340mL of diesel oil. The mixture was then stirred at 10000r / min for 20min using a high-speed mixer. 4.0g of quicklime was added, and the mixture was stirred at high speed for another 20min. 60mL of 30% CaCl2 aqueous phase was added, and the mixture was stirred at high speed for another 30min. 8.0g of organo-bentonite was added, and the mixture was stirred at high speed for another 20min. 2.0g of shearing agent was added, and the mixture was stirred at high speed for another 20min. 2.4g of wetting agent was added, and the mixture was stirred at high speed for another 20min. 8g of organo-lignite was added, and the mixture was stirred at high speed for another 20min. 8g of oxidized asphalt was added, and the mixture was stirred at high speed for another 20min. Finally, barite was added, and the mixture was stirred at high speed for another 30min to obtain a low oil-water ratio, low soil phase oil-based drilling fluid.

[0114] (3) The performance evaluation of drilling fluid is the same as in Example 2.

[0115] Example 6

[0116] This embodiment prepares an oil-based drilling fluid and evaluates its performance, including the following processes:

[0117] (1) The drilling fluid formulation is the same as in Example 2, but the density is increased to 2.0 g / cm³. 3 .

[0118] (2) The drilling fluid preparation method is the same as in Example 2.

[0119] (3) Performance evaluation of drilling fluid:

[0120] Before conducting the drilling fluid aging performance test, the performance of the drilling fluid at 50℃ was first tested, and the results are shown in Table 2. Then, the drilling fluid was placed in a high-temperature aging tank and aged at 150℃ for 16 hours. After cooling to 50℃, the performance of the aged drilling fluid was tested, and the results are shown in Table 2.

[0121] Example 7

[0122] This embodiment prepares an oil-based drilling fluid and evaluates its performance, including the following processes:

[0123] (1) The drilling fluid formula is the same as in Example 2.

[0124] (2) The drilling fluid preparation method is the same as in Example 2.

[0125] (3) Performance evaluation of drilling fluid:

[0126] Before conducting the drilling fluid aging performance test, the performance of the drilling fluid at 50℃ was first tested, and the results are shown in Table 2. Then, the drilling fluid was placed in a high-temperature aging tank and aged at 180℃ for 16 hours. After cooling to 50℃, the performance of the aged drilling fluid was tested, and the results are shown in Table 2.

[0127] As can be seen from the data in Examples 2-5 of Table 2, with the increase of oil-water ratio, the amount of organic bentonite added slightly increases, the plastic viscosity and dynamic shear force of the drilling fluid do not change much, the demulsification voltage of the drilling fluid increases, and the stability improves. For the low oil-water ratio, low soil phase oil-based drilling fluid of the present invention, even with an oil-water ratio as low as 70:30 and an organic soil addition of only 1.2%, the oil-based drilling fluid still exhibits good electrical stability and settling stability, indicating that the drilling fluid system has excellent performance. At the same time, the reduction of oil-water ratio also greatly saves the cost of drilling fluid base oil.

[0128] As can be seen from the data in Examples 2-5 in Table 3, as the oil-water ratio increases, the system exhibits good fluidity after freezing at -25℃, which can meet the needs of on-site construction at -25℃ in winter.

[0129] As can be seen from the data in Examples 2 and 7 of Table 2, under the conditions of an oil-water ratio of 70:30 and an organic bentonite content of 1.2%, the demulsification voltage decreased slightly with the increase of aging temperature, but remained greater than 800V; the plastic viscosity and dynamic shear strength of the drilling fluid decreased slightly, but the overall changes were not significant, and the high-temperature and high-pressure filtration loss was still no more than 3mL. This indicates that the low oil-water ratio, low soil phase oil-based drilling fluid of the present invention has good temperature resistance in the range below 180℃.

[0130] As can be seen from the data in Examples 6 and 7 of Table 2, under the conditions of an oil-water ratio of 70:30 and an organic bentonite content of 1.2%, the density of the oil-based drilling fluid increased to 2.0 g / cm³. 3 The oil-based drilling fluid still exhibits good rheological properties, emulsification stability, and sedimentation stability, with a high demulsification voltage, meeting field requirements. This indicates that the density range of the low oil-water ratio, low soil phase oil-based drilling fluid of this invention is 1.6-2.0 g / cm³. 3 Adjustable within the range.

[0131] Table 2 Performance of Low Oil-Water Ratio, Low Soil Phase Oil-Based Drilling Fluids

[0132]

[0133] Table 3 Performance evaluation of drilling fluids with different oil-water ratios at low temperatures

[0134]

[0135] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A high-efficiency emulsifier, characterized in that, The emulsifier is prepared by reacting olefinic acid, organic amine, and alcohol ether through the following steps: heating the olefinic acid to 65°C and then adding the organic amine, continuing to raise the temperature to 160-170°C for reaction; after the reaction is completed, cooling to 70-90°C and then adding sulfur trioxide for reaction; after the reaction is completed, adding the alcohol ether for further reaction, and cooling to room temperature after the reaction is completed to obtain the high-efficiency emulsifier. The mass ratio of the olefinic acid, organic amine and alcohol ether is (55-58):(13-18):(17-19); The enoic acid is C. 20 -Tetraenoic acid; The organic amine is ethyleneamine and hydroxypropyl diamine, and the mass ratio of ethyleneamine to hydroxypropyl diamine is (10-8):(8-10).

2. The high-efficiency emulsifier according to claim 1, characterized in that, The alcohol ether is a diethylene glycol ether.

3. A low oil-water ratio, low soil phase oil-based drilling fluid, characterized in that, The oil-based drilling fluid includes an oil phase, an aqueous phase, the high-efficiency emulsifier, wetting agent, organobentonite, shearing agent, lignite filtration loss reducer, asphalt, quicklime, and weighting agent as described in claim 1 or 2. The oil-water ratio of the oil-based drilling fluid is (70:30) to (85:15); based on the total volume of the oil phase and the water phase being 100%, the amount of organic bentonite added is 1.2wt% to 2.0wt%.

4. The oil-based drilling fluid according to claim 3, characterized in that, The drilling fluid has an oil-to-water ratio of (70:30) to (80:20), and based on the total volume of the oil and water phases being 100%, the amount of organic bentonite added is 1.2wt% to 1.5wt%.

5. The oil-based drilling fluid according to claim 3, characterized in that, Based on the total volume of the oil and water phases being 100%, the oil-based drilling fluid comprises: Oil phase 70.0 v%~85.0 v%; Aqueous phase 15.0 v%~30.0 v%; Organic bentonite 1.2wt%~2.0wt%; High-efficiency emulsifier 2.5wt%~4.5wt%; Cutting agent 0.5wt%~1.0wt%; Filtration loss reducer 3.0wt%~5.0wt%; Wetting agent 0.5wt%~1.0wt%; Quicklime 1.0wt%~2.0wt%; The amount of weighting agent added is determined according to the density requirements of the oil-based drilling fluid.

6. The oil-based drilling fluid according to claim 3, characterized in that, Based on the total volume of the oil and water phases being 100%, the oil-based drilling fluid comprises: Oil phase 70.0 v%~80.0 v%; Aqueous phase 20.0 v%~30.0 v%; Organic bentonite 1.2wt%~1.5wt%; High-efficiency emulsifier 3.0wt%~4.5wt%; Cutting agent 0.5wt%~1.0wt%; Filtration loss reducer 4.0wt%~4.5wt%; Wetting agent 0.5wt%~1.0wt%; Quicklime 1.5wt%~2.0wt%; The amount of weighting agent added is determined according to the density requirements of the oil-based drilling fluid.

7. The oil-based drilling fluid according to any one of claims 3-6, characterized in that, The oil phase is 0# diesel oil.

8. The oil-based drilling fluid according to claim 7, characterized in that, The aqueous phase is a salt solution, and the solute in the salt solution is calcium chloride and / or potassium chloride; the concentration of the salt solution is 20wt%~40wt%.

9. The oil-based drilling fluid according to claim 7, characterized in that, The cutting agent is a resin-based cutting agent.

10. The oil-based drilling fluid according to claim 7, characterized in that, The filtration loss reducing agent includes organic lignite filtration loss reducing agent and oxidized bitumen.

11. The oil-based drilling fluid according to claim 7, characterized in that, The wetting agent is an alkylolamide derivative wetting agent.

12. A method for preparing the oil-based drilling fluid according to any one of claims 3-11, characterized in that, The preparation method includes the following steps: S1. Mix the oil phase and the high-efficiency emulsifier to obtain mixture I; S2. Mix the mixture I, the aqueous phase, and quicklime to obtain mixture II; S3. Mix the mixture II, organic bentonite and cutting agent to obtain mixture III; S4. Mix the mixture III, wetting agent, filtration reducer and weighting agent to obtain the oil-based drilling fluid.

13. The preparation method according to claim 12, characterized in that, The mixing time is 20 min to 30 min; the mixing speed is 8000 r / min to 12000 r / min.

Images