Oil-based drilling fluid shear enhancer, preparation method thereof and high-density oil-based drilling fluid

Abstract

The present invention provides an oil-based drilling fluid shearing agent, a preparation method thereof and a high-density oil-based drilling fluid, wherein the oil-based drilling fluid shearing agent has a long-chain lipophilic group and multiple hydrophilic groups in the molecule; the oil-based drilling fluid shearing agent is prepared by esterification reaction of fatty acid and oligoamide substances; the fatty acid is selected from one or more of oleic acid, rosin acid, stearic acid, dodecylbenzenesulfonic acid and lauric acid; the oligoamide substances are obtained by reaction of oligomeric acid and organic amine, the oligomeric acid is selected from one or two of dimer acid and trimer acid, and the organic amine is selected from one or more of diethanolamine and polyethylene polyamine. The treating agent has an amphiphilic structure, has multiple hydrophilic groups and long-chain lipophilic groups in the molecule, has high temperature resistance, is helpful to improve or maintain the adhesion and shear of ultra-high density oil-based drilling fluid after high-temperature aging, thereby being beneficial to improving its high-temperature sedimentation stability, and the temperature resistance reaches 200°C.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum drilling, and in particular relates to an oil-based drilling fluid shear enhancer, a preparation method thereof and high-density oil-based drilling fluid. Background Art

[0002] With the development of unconventional oil and gas resources, shale, highly water-sensitive formations, abnormally high-pressure formations, and high-temperature and high-pressure formations have put forward higher requirements for high-density and ultra-high-density oil-based drilling fluid technology. According to the general density classification standard of drilling fluid, the density is greater than 2.3g / cm 3 It belongs to ultra-high density drilling fluid. In practical applications, organic soil and emulsion droplets are often used as viscosity-enhancing and shear-enhancing agents in oil-based drilling fluids. However, in high-temperature formations (above 200°C), organic soil is passivated, and the organic soil modified by intercalation is desorbed from the modifier, which ultimately leads to problems such as poor sedimentation stability and rheological instability of ultra-high density oil-based drilling fluids at high temperatures.

[0003] In order to meet the needs of unconventional oil and gas reservoirs and complex formation exploration and development, many scholars and research institutions have conducted in-depth research on high-density oil-based drilling fluids. The Chinese patent document with application number 201711443636.3 discloses a high-density oil-based drilling fluid that is resistant to salt water intrusion and a preparation method thereof. The raw material composition includes a certain weight ratio of fatty acid amide, alkanolamide, alkalinity regulator, organic soil, filtration reducer, barite, inorganic chloride salt solution and oil, among which the raw material composition of fatty acid amide is unsaturated fatty acid, diethylenetriamine, hydroxyethylethylenediamine and dodecylbenzene sulfonic acid; the raw material composition of alkanolamide is unsaturated fatty acid, diethanolamine and dodecylbenzene sulfonic acid. The above-mentioned high-density oil-based drilling fluid can withstand temperatures of up to 200°C and has a maximum density of 2.6g / cm 3 , and can resist 60% of salt water pollution, stable performance after aging, and good sedimentation stability. However, the drilling fluid lacks continuous temperature resistance (continuous high temperature aging for more than 72 hours), which is not conducive to application in long-term complex situations in the wellbore.

[0004] How to ensure that high-density drilling fluid has good long-term temperature resistance, high-temperature sedimentation stability and anti-pollution ability has become an important issue faced by the research and application of high-density full oil-based drilling fluid. At the same time, due to the defects of high-temperature and high-density drilling fluid treatment agents such as poor temperature resistance and short action cycle, the maintenance amount of treatment agents is large, which increases the cost of drilling fluid. The development of new treatment agents has also become an urgent problem for high-temperature and high-density oil-based drilling fluids. Summary of the invention

[0005] In view of this, the present application provides an oil-based drilling fluid shearing agent, a preparation method thereof and a high-density oil-based drilling fluid. The shearing agent provided by the present invention has good temperature resistance and shearing performance, which helps to improve or maintain the viscosity and shear of the high-density oil-based drilling fluid after high-temperature aging, thereby helping to improve its high-temperature sedimentation stability.

[0006] The invention provides an oil-based drilling fluid shearing agent, wherein the oil-based drilling fluid shearing agent has a long-chain lipophilic group and a plurality of hydrophilic groups in a molecule; the oil-based drilling fluid shearing agent is prepared by esterification reaction of fatty acid and oligoamide substances; the fatty acid is selected from one or more of oleic acid, rosin acid, stearic acid, dodecylbenzenesulfonic acid and lauric acid; the oligoamide substances are obtained by reaction of oligomeric acid and organic amine, the oligomeric acid is selected from one or two of dimer acid and trimer acid, and the organic amine is selected from one or more of diethanolamine and polyethylene polyamine.

[0007] The present invention provides a method for preparing an oil-based drilling fluid shearing agent, comprising the following steps:

[0008] S1, reacting the oligomeric acid with an organic amine to obtain an amide intermediate product;

[0009] S2, esterifying the amide intermediate product with fatty acid to obtain an oil-based drilling fluid shearing agent;

[0010] The oligomeric acid is selected from one or both of dimer acid and trimer acid, the organic amine is selected from one or more of diethanolamine and polyethylene polyamine; the fatty acid is selected from one or more of oleic acid, rosin acid, stearic acid, dodecylbenzene sulfonic acid and lauric acid.

[0011] Preferably, in step S1, the molar ratio of the oligomeric acid to the organic amine is (1:1) to (1:4), the reaction temperature is 130 to 180° C.; the reaction is carried out under stirring conditions, and the reaction time is 4 to 8 hours.

[0012] Preferably, in step S2, the mass ratio of the fatty acid to the amide intermediate product is (1:1) to (1:2).

[0013] Preferably, in step S2, the esterification reaction is carried out in the presence of a catalyst, and the catalyst is one of p-toluenesulfonic acid, molecular sieves and DMAP.

[0014] Preferably, the mass of the catalyst is 1% to 5% of the total mass of the raw materials used for preparation; the temperature of the esterification reaction is 120 to 180° C., and the time is 4 to 8 hours.

[0015] Compared with the prior art, the shear-reducing agent provided by the present invention is a high-temperature stable shear-reducing agent with a multi-branched configuration. By selecting a branched monomer with good temperature resistance as the core, and then undergoing a series of organic reactions with other monomers, a high-density oil-based drilling fluid treatment agent with temperature resistance and shear-reducing performance is finally obtained. The treatment agent has an amphiphilic structure, with multiple hydrophilic groups and long-chain lipophilic groups in the molecule, and has high temperature resistance, which helps to improve or maintain the shear resistance of ultra-high-density oil-based drilling fluid after high-temperature aging, thereby helping to improve its high-temperature sedimentation stability, and the temperature resistance reaches 200°C.

[0016] In the process of preparing the shearing agent of the present invention, the organic amine and the oligomeric acid form an amide product with a branched chain, and the amide product continues to react with the fatty acid to form a chain extension, increase the length of the branch chain, and obtain the shearing agent. Under the same molecular weight, the more branches the shearing agent has, the smaller the mechanical radius is, and the lower the viscosity effect is. In particular, when added to a high-density oil-based drilling fluid, it has a low-viscosity shearing effect, thereby improving the sedimentation stability and rheology of the high-density oil-based drilling fluid at high temperatures.

[0017] The shearing agent prepared in the embodiment of the present invention is a high-temperature shearing agent for high-density oil-based drilling fluid, which has stable reaction conditions, is easy to operate, does not require solvents, has low equipment requirements, and is easy to industrialize. Compared with existing shearing agents and organic soils, the obtained product has good thermal stability, strong shearing ability, and low addition amount, and the prepared high-density oil-based drilling fluid can resist temperatures above 200°C.

[0018] The present invention provides a high-density oil-based drilling fluid, comprising a base oil and a treating agent, wherein the treating agent comprises the above-mentioned oil-based drilling fluid shear enhancing agent.

[0019] Preferably, in the high-density oil-based drilling fluid, the oil phase and the water phase mixture are composed of base oil and a calcium chloride aqueous solution with a mass concentration of 20% to 30%. The treatment agent includes, based on the percentage of the total volume of the oil phase and the water phase mixture: 1% to 3% of organic soil; 3.5% to 6% of emulsifier; 2.5% to 5% of wetting agent; 2% to 4% of filtration reducer; 3% to 5% of alkalinity regulator; and 2% to 4% of the oil-based drilling fluid shearing agent.

[0020] Preferably, the base oil is one of 3# mineral white oil, 5# mineral white oil and 0# diesel, and the volume ratio of the oil phase to the water phase is preferably 85:15 to 95:5.

[0021] Preferably, the emulsifier is a fatty amide substance; the wetting agent is at least one of a long alkyl chain quaternary ammonium salt cationic surfactant, a long alkyl chain anionic surfactant, a long chain alkyl alcohol ether nonionic surfactant and a long chain alkyl polyoxyethylene ether nonionic surfactant; the alkalinity regulator is quicklime; and the fluid loss reducer is at least one of oxidized asphalt and organic lignite.

[0022] The high-density oil-based drilling fluid provided by the present invention is resistant to high temperatures and can be used in complex drilling operations such as deep wells, ultra-deep wells, abnormally high-pressure wells, and highly water-sensitive formations; moreover, it has good continuous temperature resistance, and the drilling fluid has been continuously aged at 180°C for 72 hours, and the performance is stable, which can meet the requirements of drilling fluid performance under special working conditions such as mid-way testing, long-term drilling, and long-term drilling stop during high-temperature drilling, and can effectively avoid sedimentation and drill jamming accidents. In addition, the high-density oil-based drilling fluid provided by the present invention has good resistance to salt water intrusion pollution. The sodium chloride brine or calcium chloride brine or composite brine with a preparation concentration of 20% can resist salt water intrusion pollution by up to 30%. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other examples improved or modified by ordinary technicians in this field belong to the scope of protection of the present invention.

[0024] The invention provides an oil-based drilling fluid shearing agent, wherein the oil-based drilling fluid shearing agent has a long-chain lipophilic group and a plurality of hydrophilic groups in a molecule; the oil-based drilling fluid shearing agent is prepared by esterification reaction of fatty acid and oligoamide substances; the fatty acid is selected from one or more of oleic acid, rosin acid, stearic acid, dodecylbenzenesulfonic acid and lauric acid; the oligoamide substances are obtained by reaction of oligomeric acid and organic amine, the oligomeric acid is selected from one or two of dimer acid and trimer acid, and the organic amine is selected from one or more of diethanolamine and polyethylene polyamine.

[0025] The present invention provides a method for preparing an oil-based drilling fluid shearing agent, comprising the following steps:

[0026] S1, reacting the oligomeric acid with an organic amine to obtain an amide intermediate product;

[0027] S2, esterifying the amide intermediate product with fatty acid to obtain an oil-based drilling fluid shearing agent;

[0028] The oligomeric acid is selected from one or both of dimer acid and trimer acid, the organic amine is selected from one or more of diethanolamine and polyethylene polyamine; the fatty acid is selected from one or more of oleic acid, rosin acid, stearic acid, dodecylbenzene sulfonic acid and lauric acid.

[0029] The shear-reducing agent provided by the invention has good temperature resistance and shear-reducing performance, helps to improve or maintain the shear adhesion of high-density oil-based drilling fluid after high-temperature aging, thereby facilitating the improvement of its high-temperature sedimentation stability and facilitating its application.

[0030] In the embodiment of the present invention, oligomeric acid and organic amine are first added to the reactor, and the temperature is slowly raised to react to obtain an amide intermediate product; then, fatty acid is continuously added to the reactor, and the temperature is raised to perform an esterification reaction to obtain a target product.

[0031] In the present invention, the oligomeric acid is selected from one or two of dimer acid and trimer acid, such as octadecadienoic acid trimer, octadecadienoic acid dimer, trimerized linoleic acid; the present invention selects a branched monomer with good temperature resistance as the core, and performs a series of organic reactions with organic amines and fatty acids. Among them, the organic amine is selected from one or more of diethanolamine and polyethylene polyamine, preferably one or more of diethylenetriamine, triethylenetetramine, tetraethylenepentamine and diethanolamine, more preferably diethylenetriamine or diethanolamine; the organic amine reacts with the oligomeric acid to form a branched amide product. The molar ratio of the oligomeric acid to the organic amine is preferably (1:1) to (1:4); the temperature of the reaction is preferably 130 to 180°C, more preferably 135°C to 160°C. The reaction described in the embodiment of the present invention is carried out in a device with stirring, a thermometer and a water separator, and the reaction time is preferably 4h to 8h, such as 5h, 6h, 8h; the intermediate product is obtained after the reaction, which is generally a brown liquid amide intermediate product.

[0032] In the embodiment of the present invention, the temperature can be appropriately lowered to below 100° C., preferably under a protective atmosphere, and then the fatty acid and the catalyst are added to the above reactor to continue to react with the obtained intermediate product to form a chain extension and increase the length of the branch chain.

[0033] In the present invention, the fatty acid is selected from one or more of oleic acid, abietic acid, stearic acid, dodecylbenzenesulfonic acid and lauric acid, preferably oleic acid or dodecylbenzenesulfonic acid. The mass ratio of the fatty acid to the amide intermediate is preferably (1:1) to (1:2); the mass of the catalyst is preferably 1% to 5% of the total mass of the raw materials used for preparation, and more preferably 2% to 5%. The catalyst is preferably one of p-toluenesulfonic acid, molecular sieves and DMAP (4-dimethylaminopyridine), and p-toluenesulfonic acid is more preferred, which has a better effect. The temperature of the esterification reaction is preferably 120 to 180°C, more preferably 130 to 160°C, and the reaction time is preferably 4h to 8h, until no water droplets appear, the reaction is terminated, and a brown viscous target product is obtained. The product is taken out after cooling to room temperature, which is the shearing agent.

[0034] The shearing agent described in the embodiment of the present invention can be called a high-temperature (stable) shearing agent, an oil-based drilling fluid (for) shearing agent, and an oil-based drilling fluid high-temperature stable shearing agent; the treating agent has an amphiphilic structure, and has multiple hydrophilic groups and long-chain lipophilic groups in the molecule, including amide groups, alkyl chains, etc., and is a multi-branched oligoamide. Under the same molecular weight, the more branches the shearing agent has, the smaller the mechanical radius, and the lower the viscosity effect. In particular, when added to high-density oil-based drilling fluid, it has a low-viscosity shearing effect, thereby improving the sedimentation stability and rheology of high-density oil-based drilling fluid at high temperatures.

[0035] The shearing agent described in the present application is itself a viscous liquid. The actual viscosity refers to the viscosity added to the high-density drilling fluid, and the viscosity of the drilling fluid is mainly affected by the water content, organic soil content, density, etc. After adding the shearing agent, the apparent viscosity of the high-density drilling fluid system described in the embodiment of the present application can be controlled at 60 to 120 mPa.s.

[0036] In some specific embodiments, the oil-based drilling fluid cutting agent has the following structure:

[0037]

[0038] Wherein, R1, R2, and R5 may be an alkyl chain having 6 carbon atoms;

[0039] R3, R4, R7, and R8 are alkyl chains having 12 to 20 carbon atoms;

[0040] R6 can be an alkyl chain having 7 carbon atoms.

[0041] Accordingly, the present invention provides a high-density oil-based drilling fluid, comprising a base oil and a treating agent, wherein the treating agent comprises the oil-based drilling fluid shear enhancing agent described above.

[0042] The high-density oil-based drilling fluid provided by the present invention can be called high-temperature resistant ultra-high-density oil-based drilling fluid, and its density can reach 2.6g / cm 3 (It is generally believed that the density of ultra-high density drilling fluid should be greater than 2.3g / cm 3 ), can withstand high temperatures, has good continuous temperature resistance, and has good resistance to salt water intrusion and pollution. It can be used in complex drilling operations such as deep wells, ultra-deep wells, abnormally high-pressure wells, and highly water-sensitive formations.

[0043] The high-density oil-based drilling fluid provided in the embodiment of the present invention can be a full oil base, or a mixed liquid consisting of an oil phase and an aqueous phase composed of a base oil and a calcium chloride aqueous solution with a mass concentration of 20% to 30%, wherein the volume ratio of the oil phase to the aqueous phase is preferably 85:15 to 95:5, for example, 90:10. In the embodiment of the present invention, the base oil can be one of 3# mineral white oil, 5# mineral white oil and 0# diesel.

[0044] The treatment agent of the present invention includes the oil-based drilling fluid shearing agent mentioned above, which plays a role in shearing or stabilizing shear in the drilling fluid; its general structural formula is shown in Formula I, for example, and the amount added can be 2% to 4% (mass volume ratio). In addition, the present invention also uses other treatment agents such as emulsifiers and weighting agents. In an embodiment of the present invention, the treatment agent includes, in terms of percentage of the total volume of the oil phase and the aqueous phase mixture: 1% to 3% of organic soil; 3.5% to 6% of emulsifier; 2.5% to 5% of wetting agent; 2% to 4% of filtration reducer; 3% to 5% of alkalinity regulator; 2% to 4% of the oil-based drilling fluid shearing agent; the weighting agent is added in an amount of 400% to 450%.

[0045] In the embodiment of the present invention, the emulsifier is preferably a fatty amide substance, which can be specifically prepared by amidation reaction of fatty acids, organic amines and organic acids, and has good emulsification, wetting and dispersion effects in drilling fluids to ensure the stability of water-in-oil emulsions. Specifically, the emulsifier has the following formula II structure:

[0046]

[0047] Wherein, X1, X3, X5 and X6 are partial structures of fatty acids, which are composed of long alkyl chains with 10 to 20 carbon atoms;

[0048] The structure of organic polyamine is H2N-(CH2-CH2-NH)X4-NH2, where X4 is an alkylene group having 1 to 3 carbon atoms;

[0049] X4 is a structural fragment of an acid anhydride or a dibasic acid, and is composed of a carbon chain having 2 to 6 carbon atoms.

[0050] The emulsifier can be an existing product independently developed by our company, which is a high temperature resistant polyamide emulsifier. The emulsifier is usually added in an amount of 3% to 5%, with a temperature resistance of 200°C and an applicable oil-water ratio range of 70:30 to full oil base; adding 2% in an oil-in-water ratio of 80:20, the emulsification rate is >90%; adding it to high-density oil-based drilling fluid (ρ>2.3g / cm 3 ), after aging, the emulsion breaking voltage ES>600V.

[0051] The preparation method of the emulsifier described in the embodiment of the present invention is preferably: adding organic polyamine and fatty acid in a molar ratio of 1: (1-4) to a reaction bottle, the reaction temperature is preferably 150°C-180°C, the reaction time is preferably 3-5h, to obtain an intermediate product A, and then adding anhydride to the reaction bottle to continue reacting with the intermediate product A, the molar ratio is preferably 1: (1-2), the reaction temperature is preferably 160°C-200°C, the reaction time is preferably 4-6h, and cooling to room temperature to obtain a viscous liquid, which is the emulsifier with good temperature resistance used in the present invention, which can be provided by Zhongyuan Drilling Engineering Technology Research Institute.

[0052] In a preferred embodiment of the present invention, the organic soil is prepared by modifying montmorillonite with organic ammonium and an activator, and mainly plays the role of increasing viscosity and reducing filtration in drilling fluid. The organic ammonium includes a long alkyl chain intercalant with a carbon number of 12 to 20.

[0053] The wetting agent is preferably at least one of a long alkyl chain quaternary ammonium salt cationic surfactant, a long alkyl chain anionic surfactant, a long chain alkyl alcohol ether nonionic surfactant and a long chain alkyl polyoxyethylene ether nonionic surfactant, and mainly plays the role of wetting barite and improving the flow pattern of the drilling fluid in the drilling fluid.

[0054] The alkalinity regulator is preferably quicklime, which is used to adjust the alkalinity of the drilling fluid and exert the effectiveness of other compatible treatment agents; at the same time, it helps the emulsifier to form a "wedge-shaped" structure and improve the high-temperature stability of the emulsion; it can also provide an alkaline environment for the drilling fluid to prevent the escape of acidic gas in the formation.

[0055] The fluid loss reducer is at least one of oxidized asphalt and organic lignite, which mainly plays the role of reducing fluid loss and improving mud cake quality in drilling fluid. The weighting agent is ordinary barite, which is weighted to the designed density according to the designed safety density window.

[0056] In an embodiment of the present invention, the preparation method of the high temperature resistant ultra-high density oil-based drilling fluid is:

[0057] According to the oil-water ratio, the base oil is measured and added to the high-stirring cup; the high-stirring speed is 10000-11000r / min, the emulsifier is added to the high-stirring cup and stirred at high speed for 10 minutes, the calcium chloride aqueous solution is added and stirred at high speed for 20 minutes, the organic soil, quicklime, and filtrate reducer are added and stirred at high speed for 10 minutes, the high-temperature shearing agent described above is added and stirred at high speed for 10 minutes, then the barite is added and stirred at high speed for 10 minutes, and finally the wetting agent is added and stirred at high speed for 30 minutes; the obtained drilling fluid is put into an aging tank, put into a high-temperature roller furnace for rolling aging for 16 hours, cooled to room temperature, and the drilling fluid performance is measured at 65°C.

[0058] The high temperature resistant ultra-high density oil-based drilling fluid provided by the present invention has good temperature resistance and lifting and cutting ability, good continuous temperature resistance, and the drilling fluid is continuously aged at 180°C for 72 hours, and the performance is stable, which can meet the requirements of the drilling fluid performance under special working conditions such as mid-way testing, long-term drilling, and long-term drilling stop during high-temperature drilling, and can effectively avoid sedimentation and cause drill jamming accidents. In addition, the high temperature resistant ultra-high density oil-based drilling fluid provided by the present invention has good resistance to salt water intrusion pollution; the sodium chloride brine or calcium chloride brine or composite brine with a preparation concentration of 20% can resist salt water intrusion pollution by up to 30%.

[0059] In order to further understand the present invention, the oil-based drilling fluid shearing agent, the preparation method thereof and the high-density oil-based drilling fluid provided by the present application are specifically described below in conjunction with the examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following examples.

[0060] In the following examples, oleic acid was purchased from Jinan Jiuruixin Chemical Co., Ltd., an industrial product; calcium oxide, calcium chloride, diethylenetriamine and diethanolamine were purchased from Sinopharm Reagents; dimer acid was purchased from Shanghai Zhipu Chemical Co., Ltd. The preferred oligomeric acid is obtained by self-condensation of fatty acids under the action of a catalyst, mainly dimer acid, one of which has the following structural formula:

[0061]

[0062] The drilling fluid materials used in the present invention are all industrial products, and the industry standards are strictly followed when they are purchased and used. Organic soil is purchased from Zhejiang Fenghong New Materials Co., Ltd.; organic lignite is from Shandong Deshunyuan Chemical. Organic soil, wetting agent, weighting agent (barite is mainly barium sulfate), and fluid loss reducer are all conventional materials for oil-based drilling fluids and are all commercially available products.

[0063] The performance indicators of emulsifiers have been explained above. Usually, the dosage is 3% to 5%, the temperature resistance is up to 200°C, and the applicable oil-water ratio range is 70:30 to full oil base; in the 80:20 oil-in-water ratio, the dosage is 2%, and the emulsification rate is >90%; when added to high-density oil-based drilling fluid (ρ>2.3g / cm 3 ), after aging, the emulsion breaking voltage ES>600V.

[0064] Example 1

[0065] In a 500mL four-necked flask equipped with a thermometer, a condenser and a stirrer, add 85g of dimer acid and 62g of diethanolamine, slowly heat to 160°C for reaction, and after 8h of reaction, a brown liquid product is obtained; continue to add 170g of oleic acid and 30g of p-toluenesulfonic acid to the reaction flask, heat to 140°C, and continue to react for 5h to obtain a brown viscous target product, then cool to room temperature and take out the product, which is the high-temperature stable cutting agent G1 for ultra-high density oil-based drilling fluid.

[0066] The performance of the shearing agent G1 prepared in Example 1 is reflected in the ultra-high density oil-based drilling fluid, mainly through the dynamic shear force YP and the initial shear Gel 10s The performance results are shown in Table 1.

[0067] A high temperature resistant ultra-high density oil-based drilling fluid: 190mL 3 #White oil + 12.0g emulsifier + 10mL calcium chloride aqueous solution (25%wt) + 2.0g organic soil + 8.0g CaO + 10.0g organic lignite + 6.0g shearing agent G1 + 6.0g wetting agent + 850g barite, density ρ = 2.5g / cm 3 .

[0068] The specific preparation steps and performance evaluation are as follows:

[0069] (1) Add 190 mL of 3# white oil into a high-stirring cup, then add 12.0 g of emulsifier into the high-stirring cup, set the high-stirring machine speed at 10000 r / min, stir at high speed for 10 min, and emulsify evenly;

[0070] (2) Add calcium chloride solution (25% concentration) into a high-stirring cup under stirring and stir at high speed for 20 minutes;

[0071] (3) While stirring, add 2.0 g of organic soil, 8.0 g of CaO, and 10.0 g of organic lignite into a high-stirring cup and stir at high speed for 10 min;

[0072] (4) While stirring, add 6.0 g of high temperature shearing agent into the high stirring cup and stir at high speed for 10 min until it is evenly stirred;

[0073] (5) While stirring, slowly add 850 g of barite into the high-stirring cup in two portions and stir at high speed for 10 min;

[0074] (6) Remove the high stirring cup, add 6.0 g of wetting agent, and continue stirring at high speed for 30 minutes.

[0075] (7) Place the prepared drilling fluid into an aging tank, seal it, and place it in a roller furnace for aging for 16 hours.

[0076] After the drilling fluid is aged at 200℃, the rheological properties and demulsification voltage at 65℃ are measured, and finally the high temperature and high pressure filtration loss (HTHP) is measured. FL , the performance is shown in Table 1.

[0077] Comparative Example 1

[0078] In an ultra-high density oil-based drilling fluid of Example 1 above, 6.0 g of the shear enhancer G1 was replaced with 6.0 g of organic soil. The drilling fluid was subjected to rolling aging at 200° C. for 16 h and the performance was measured at 65° C. The results are shown in Table 1.

[0079] Table 1 Performance of shear enhancer G1 and ultra-high density oil-based drilling fluid after aging at 200℃

[0080]

[0081] Example 2

[0082] In a 500mL four-necked flask equipped with a thermometer, condenser, and stirrer, 100g of dimer acid and 50g of diethanolamine were added, and the temperature was slowly raised to 180°C for reaction. After 5h of reaction, a brown product was obtained; 180g of dodecylbenzenesulfonic acid and 40g of p-toluenesulfonic acid were added to the reaction flask, and the reaction was carried out at 150°C for 6h to obtain a brown viscous target product, and then the temperature was lowered to room temperature, and the product was taken out, which was the high-temperature stable shearing agent G2 for ultra-high density oil-based drilling fluid. The performance results are shown in Table 2.

[0083] A high temperature resistant ultra-high density oil-based drilling fluid: 180 mL diesel + 12.0 g emulsifier + 20 mL calcium chloride aqueous solution (25% wt) + 3.0 g organic soil + 8.0 g CaO + 6.0 g organic lignite + 4.0 g oxidized asphalt + 6.0 g shearing agent G2 + 6.0 g wetting agent + 730 g barite, density ρ = 2.4 g / cm 3 .

[0084] According to the preparation steps of Example 1, the drilling fluid was aged at 180°C for 16 h, and the rheological properties and demulsification voltage at 65°C were measured, and the high temperature and high pressure filtration loss (HTHP) was measured. FL , the performance is shown in Table 2.

[0085] Comparative Example 2

[0086] In an ultra-high density oil-based drilling fluid in Example 2, 6.0 g of the shear enhancer G2 was replaced with 6.0 g of organic soil. The drilling fluid was subjected to rolling aging at 180° C. for 16 h, and the performance was measured at 65° C. The results are shown in Table 2.

[0087] Table 2 Performance of shear enhancer G2 and ultra-high density oil-based drilling fluid after aging at 180°C

[0088]

[0089] Example 3

[0090] In a 500mL four-necked flask equipped with a thermometer, condenser, and stirrer, add 85g of trimerized linoleic acid and 31g of diethylenetriamine, slowly heat to 150°C for reaction, and after 6h of reaction, obtain a brown liquid product; continue to add 180g of oleic acid and 50g of p-toluenesulfonic acid to the reaction flask, continue to react at 150°C for 4h, obtain a brown viscous target product, then cool to room temperature, take out the product, which is the high temperature stable shear enhancer G3 for ultra-high density oil-based drilling fluid. The performance results are shown in Table 3.

[0091] A high temperature resistant ultra-high density oil-based drilling fluid, 200mL diesel + 12.0g emulsifier + 4.0g organic soil + 8.0g CaO + 10.0g organic lignite + 6.0g cutting agent G3 + 8.0g wetting agent + 920g barite, density ρ = 2.56g / cm 3 .

[0092] According to the preparation steps of Example 1, the drilling fluid was aged at 230°C for 16 h, and the rheological properties and demulsification voltage at 65°C were measured. Then, the high temperature and high pressure filtration loss (HTHP) was measured. FL , the performance is shown in Table 3.

[0093] Comparative Example 3

[0094] In an ultra-high density oil-based drilling fluid in Example 3, 6.0 g of the shear enhancer G3 was replaced with 6.0 g of organic soil. The drilling fluid was subjected to rolling aging at 230° C. for 16 h, and the performance was measured at 65° C. The results are shown in Table 3.

[0095] Table 3 Performance of shear enhancer G3 and high temperature resistant ultra-high density oil-based drilling fluid after aging

[0096]

[0097] The high temperature stable shearing agent G1, G2, and G3 provided by the present invention were used in the examples, while the organic soil was used as a substitute treatment agent for the high temperature stable shearing agent in the comparative example.

[0098] In Example 1, the drilling fluid density is 2.5 g / cm 3 , aging at 200℃ for 16h, apparent viscosity AV: 104mPa·s, plastic viscosity PV: 88mPa·s, dynamic shear force YP: 16Pa, initial cutting Gel 10s :7.5Pa, high temperature and high pressure filtration HTHP FL :4.4mL, demulsification voltage ES:1800V. In Example 2, the drilling fluid density is 2.4g / cm 3 , drilling fluid 180℃ / 16h, AV:84mPa·s, PV:73mPa·s, YP:11Pa, initial cutting Gel 10s :4.5Pa,HTHP FL :3.2mL, demulsification voltage ES:1551V. The drilling fluid density in Example 3 is 2.56g / cm 3 , 230℃ / 16h, AV: 76mPa·s, PV: 63mPa·s, YP: 13Pa, Gel 10s :6Pa, HTHP FL:3.6mL, demulsification voltage ES:2054V. The experimental results in Table 1, Table 2, and Table 3 all show that the rheology and initial cutting properties of the drilling fluid in the embodiment after high temperature aging are better than those of the drilling fluid in the comparative example, indicating that the prepared shearing agent has a better shearing effect.

[0099] It should be noted that rheological properties are mainly expressed by the apparent viscosity AV (mPa·s) and plastic viscosity PV (mPa·s) after aging, which are professional terms. The lower the AV and PV and the larger the YP, the better the rheological properties. 10s It is also a professional term. The larger the value, the stronger the drilling fluid's cutting ability and the stronger its ability to suspend rock cuttings. This means that the cutting agent has better resistance to temperature and cutting. However, the initial cutting gel 10s It also cannot be too large, otherwise it will affect the drilling pump pressure.

[0100] Example 4

[0101] Provide a high temperature resistant ultra-high density oil-based drilling fluid, and test its rheological properties and sedimentation stability after continuous aging for 72 hours. The drilling fluid density ρ = 2.5g / cm 3 , oil-water ratio 95:5, aging temperature 180°C. The drilling fluid is prepared by adding the following components in percentage: 0# diesel: 190mL, emulsifier 16.0g, calcium chloride aqueous solution 10mL (25wt%), organic soil 5.0g, quicklime 8.0g, oxidized asphalt 8.0g, high temperature shearing agent G1 in Example 1 8.0g, wetting agent 7.0g, barite 850g; three portions are prepared.

[0102] The first portion was placed in an aging tank, sealed, and placed in a roller furnace for aging at 180°C for 16 hours, then cooled to room temperature, and the rheological properties, high temperature and high pressure filtration and demulsification voltage at 65°C were measured. The properties are shown in Table 4.

[0103] The second portion was placed in an aging tank, sealed, and placed in a roller furnace for continuous rolling aging at 180°C for 72 hours, then cooled to room temperature, and the rheological properties, high temperature and high pressure filtration and demulsification voltage at 65°C were measured. The properties are shown in Table 4.

[0104] The third portion was placed in an aging tank, sealed, and placed in a roller furnace for 16 hours of rolling aging at 180°C, then cooled to room temperature and stirred at high speed for 10 minutes. The third portion was placed in an aging tank for 16 hours of static aging at 180°C, and the sedimentation stability was tested. After the aging was completed, the glass rod was naturally cooled to 50°C, and the glass rod was placed in the aging tank to see if it fell freely to the bottom, poured quickly, and stirred slowly to see if there was any resistance. The performance is shown in Table 4.

[0105] The results in Table 4 show that after continuous aging for 72 hours, the apparent viscosity AV, plastic viscosity PV, dynamic shear force YP and initial shear energy of the drilling fluid are maintained in a reasonable range, and are not much different from the performance after aging for 16 hours, indicating that the drilling fluid has good long-term aging performance. Therefore, the drilling fluid has good continuous temperature resistance and sedimentation stability.

[0106] Table 4 High temperature resistance and ultra-high density oil-based drilling fluid performance Temperature resistance and sedimentation stability

[0107]

[0108] Example 5

[0109] Provide a high temperature resistant ultra-high density oil-based drilling fluid, and test its anti-salt water intrusion performance. The drilling fluid density ρ = 2.45g / cm 3 , oil-water ratio 90:10, aging temperature 180°C. The drilling fluid is prepared by adding the following components in percentage: 0# diesel: 180mL, emulsifier 16.0g, calcium chloride aqueous solution 20mL (25wt%), organic soil 5.0g, quicklime 8.0g, organic lignite 8.0g, high temperature shearing agent G1 in Example 1 8.0g, wetting agent 8.0g, barite 780g. Four portions are prepared with the same formula.

[0110] The drilling fluid was placed in an aging tank, sealed, and placed in a roller furnace for aging at 180°C for 16 h. It was then cooled to room temperature and the rheological properties, high temperature and high pressure filtration loss, and demulsification voltage were measured. The properties are shown in Table 5.

[0111] Prepare calcium chloride brine with a concentration of 20%, and conduct 10%, 20%, 30%, and 40% brine contamination experiments on ultra-high density oil-based drilling fluids, that is, take 20mL, 40mL, 60mL, and 80mL respectively and add them to the aged drilling fluids, stir at high speed for 30min, put them into the aging tank, age them at 180℃ for 16h, and then measure the rheological properties and demulsification voltage at 65℃. The properties are shown in Table 5.

[0112] Table 5 High temperature resistance and ultra-high density oil-based drilling fluid performance and resistance to salt water intrusion and pollution

[0113]

[0114] The above examples show that the drilling fluid requires a low amount of treatment agent, requires less maintenance during drilling, has strong anti-pollution ability and low overall cost; it is suitable for complex drilling operations such as deep wells, ultra-deep wells, abnormally high-pressure wells and highly water-sensitive formations, such as the Sichuan Basin and the southern edge of the Junggar Basin in Xinjiang.

[0115] The above descriptions are only preferred embodiments of the present invention. It should be pointed out that professionals in this technical field can implement various modifications to these embodiments without departing from the technical principles of the present invention, and these modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An oil-based drilling fluid shearing agent, which is a treatment agent for high-density oil-based drilling fluid, characterized in that: The oil-based drilling fluid shearing agent has a long-chain lipophilic group and multiple hydrophilic groups in its molecule; the oil-based drilling fluid shearing agent is prepared by esterification reaction of fatty acid and oligoamide substances; the fatty acid is selected from one or more of oleic acid, rosin acid, stearic acid, dodecylbenzenesulfonic acid and lauric acid; the oligoamide substances are obtained by reaction of oligomeric acid and organic amine, the oligomeric acid is selected from one or two of dimer acid and trimer acid, and the organic amine is selected from one or more of diethanolamine and polyethylene polyamine.

2. A method for preparing an oil-based drilling fluid cutting agent, comprising the following steps: S1, reacting the oligomeric acid with an organic amine to obtain an amide intermediate product; S2, esterifying the amide intermediate product with fatty acid to obtain an oil-based drilling fluid shearing agent for use in high-density oil-based drilling fluid; The oligomeric acid is selected from one or both of dimer acid and trimer acid, the organic amine is selected from one or more of diethanolamine and polyethylene polyamine; the fatty acid is selected from one or more of oleic acid, rosin acid, stearic acid, dodecylbenzene sulfonic acid and lauric acid.

3. The preparation method according to claim 2, characterized in that: In the step S1, the molar ratio of the oligomeric acid to the organic amine is (1:1) to (1:4), the reaction temperature is 130 to 180° C.; the reaction is carried out under stirring conditions, and the reaction time is 4 to 8 hours.

4. The preparation method according to claim 3, characterized in that: In the step S2, the mass ratio of the fatty acid to the amide intermediate product is (1:1) to (1:2).

5. The preparation method according to claim 2, characterized in that: In the step S2, the esterification reaction is carried out in the presence of a catalyst, and the catalyst is one of p-toluenesulfonic acid, molecular sieve and DMAP.

6. The preparation method according to claim 5, characterized in that: The mass of the catalyst is 1% to 5% of the total mass of the raw materials used for preparation; the temperature of the esterification reaction is 120 to 180° C., and the time is 4 to 8 hours.

7. A high-density oil-based drilling fluid, comprising a base oil and a treating agent, characterized in that: The treating agent comprises the oil-based drilling fluid shearing agent according to claim 1 or the oil-based drilling fluid shearing agent obtained by the preparation method according to any one of claims 2-6.

8. The high-density oil-based drilling fluid according to claim 7, characterized in that: The high-density oil-based drilling fluid comprises a base oil and a calcium chloride aqueous solution with a mass concentration of 20% to 30% to form an oil phase and an aqueous phase mixture. The treatment agent comprises, based on the percentage of the total volume of the oil phase and the aqueous phase mixture, 1% to 3% of organic soil; 3.5% to 6% of an emulsifier; 2.5% to 5% of a wetting agent; 2% to 4% of a fluid loss reducer; 3% to 5% of an alkalinity regulator; and 2% to 4% of the oil-based drilling fluid shearing agent.

9. The high-density oil-based drilling fluid according to claim 8, characterized in that: The base oil is one of 3# mineral white oil, 5# mineral white oil and 0# diesel, and the volume ratio of the oil phase to the water phase is preferably 85:15 to 95:

5.

10. The high-density oil-based drilling fluid according to claim 8, characterized in that: The emulsifier is a fatty amide substance; the wetting agent is at least one of a long alkyl chain quaternary ammonium salt cationic surfactant, a long alkyl chain anionic surfactant, a long chain alkyl alcohol ether nonionic surfactant and a long chain alkyl polyoxyethylene ether nonionic surfactant; the alkalinity regulator is quicklime; and the fluid loss reducer is at least one of oxidized asphalt and organic lignite.

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