Emulsifier for oil-based drilling fluid and preparation method thereof

Abstract

The present invention belongs to the technical field of oil and gas drilling, and specifically relates to an emulsifier for oil-based drilling fluid and a preparation method thereof. The preparation method of an emulsifier for oil-based drilling fluid of the present invention comprises the following steps: S1, subjecting waste oil regenerated fatty acid to amidation reaction with polyethylene polyamine; S2, subjecting the product of the amidation reaction in step S1 to amidation reaction with compound A; the compound A is selected from one or any combination of dicarboxylic acid compounds, polycarboxylic acid compounds, and acid anhydride compounds. The preparation method of the emulsifier for oil-based drilling fluid of the present invention uses waste oil regenerated fatty acid as a basic raw material, has more superior environmental protection and economy, and the prepared emulsifier can improve the rheology of high-density oil-based drilling fluid when used in oil-based drilling fluid, reduce the viscosity and shear force of high-density oil-based drilling fluid, speed up drilling speed, and prevent the occurrence of complicated underground situations such as leakage.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and natural gas drilling, and in particular relates to an emulsifier for oil-based drilling fluid and a preparation method thereof. Background Art

[0002] With the exploration and development of oil and gas resources, conventional deep-layer oil and gas resources can no longer meet the demand, so the development of oil and gas resources needs to develop towards deep formations, but the exploration and development of deep oil and gas resources often faces the problem of high temperature and high pressure drilling. Oil-based drilling fluid has more advantages than water-based drilling fluid in deep formation drilling and oil and gas resource exploration and development, especially in the exploration and development of shale gas, the advantages of oil-based drilling fluid are particularly prominent. Oil-based drilling fluid is a kind of oil-in-water emulsified drilling fluid, with oil as the continuous phase and water as the dispersed phase, so it has strong inhibition and is conducive to maintaining the stability of the well wall. Compared with water-based drilling fluid, it also has the advantages of high temperature resistance, salt invasion resistance, good lubricity and less damage to oil and gas layers. Therefore, oil-based drilling fluid is often used as a drilling fluid system for high-temperature and high-pressure deep wells and ultra-deep wells.

[0003] High-density drilling fluid is required for drilling high-temperature and high-pressure deep wells. Since high-density drilling fluid uses a large amount of weighting materials, the system has a high solid content, so the system will have a high viscosity. On the other hand, since conventional high-density oil-based drilling fluids use organic soil as a viscosity-enhancing and shear-enhancing agent, aging often leads to a further increase in the viscosity and shear of the system. In addition, since the drilling fluid will carry a large amount of rock cuttings during the drilling process, this will also cause the viscosity of the drilling fluid system to further increase. Although some inferior solid phases can be removed by solid phase processing equipment, many submicron particles are difficult to separate from the system. However, these submicron particles greatly affect the viscosity and shear of the system, resulting in an increase in the viscosity and shear force of the system.

[0004] As the viscosity of oil-based drilling fluid increases, the mechanical drilling speed decreases, which will extend the drilling cycle; excessively high plastic viscosity will make it difficult to pump the drilling fluid, increase the pump pressure, and cause more frequent mud pump failures; and excessively high static shear force will cause the pump to be blocked when the pump is restarted after stopping, which will cause the well pressure to rise, which may block the formation and induce complex situations such as well leakage. Therefore, in order to solve the above problems, it is necessary to add low-viscosity and low-shear emulsifiers to the oil-based drilling fluid. Among them, emulsifiers based on amide compounds are the most widely used, but the viscosity shear force of conventional amide compound emulsifiers is relatively high. Usually, the prepared 2.0g / cm 3 The Marsh funnel viscosity of the oil-based drilling fluid with the above density is ≥100s, and the dynamic shear force (yield value) is ≥12Pa. It needs to be used together with other emulsifiers to obtain low-viscosity and low-shear drilling fluid. In addition, the cost of the current amide compound oil-based drilling fluid emulsifier is relatively high. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing an emulsifier for oil-based drilling fluid, so as to solve the problem that the current amide compound oil-based drilling fluid emulsifier has a high cost.

[0006] Another object of the present invention is to provide an emulsifier for oil-based drilling fluid.

[0007] In order to achieve the above object, the technical scheme adopted by the method for preparing the emulsifier for oil-based drilling fluid of the present invention is:

[0008] A method for preparing an emulsifier for oil-based drilling fluid comprises the following steps:

[0009] S1, subjecting waste oil regenerated fatty acids to amidation reaction with polyethylene polyamine;

[0010] S2, performing an amidation reaction on the product of the amidation reaction in step S1 and compound A;

[0011] The compound A is selected from one or any combination of dicarboxylic acid compounds, polycarboxylic acid compounds, and acid anhydride compounds; the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to the polyethylene polyamine is 1:(0.8-1.2); the molar ratio of the polyethylene polyamine to the compound A is (0.8-1.2):(1-1.2).

[0012] The preparation method of the emulsifier for oil-based drilling fluid of the present invention uses fatty acid regenerated from waste oil as the basic raw material, has more superior environmental protection and economy, and the fatty acid regenerated from waste oil is mainly composed of monobasic organic carboxylic acid with 16 to 20 carbon atoms. Compared with the amide compound oil-based drilling fluid emulsifier prepared from a single fatty acid, the emulsifier prepared by the emulsifier can form a more stable oil-in-water emulsion due to the diversity of the molecular chain when used in oil-based drilling fluid, and can improve the rheological properties of high-density oil-based drilling fluid, reduce the viscosity and shear force of high-density oil-based drilling fluid, speed up the drilling speed, and prevent the occurrence of complicated downhole situations such as leakage. The prepared emulsifier for oil-based drilling fluid is used for 2.0 to 2.3 g / cm 3 The density of the oil-based drilling fluid is ≤60s, and the dynamic shear force (yield value) is ≤10Pa. It does not need to use other emulsifiers to meet the performance requirements of low-viscosity and low-shear oil-based drilling fluid.

[0013] The recycled fatty acids from waste cooking oil are mainly composed of monobasic organic carboxylic acids with 16 to 20 carbon atoms. The molar ratio of carboxyl groups in the recycled fatty acids from waste cooking oil to polyethylene polyamine refers to the ratio of the sum of the molar amounts of the carboxyl groups of all the carboxylic acids constituting the recycled fatty acids from waste cooking oil to the molar amount of polyethylene polyamine.

[0014] Preferably, the temperature of the amidation reaction in step S1 is 150-200°C. Preferably, the temperature of the amidation reaction in step S2 is 150-200°C. For example, the temperature of the amidation reaction in step S1 is 160-200°C, and the temperature of the amidation reaction in step S2 is 160-200°C. Preferably, the water generated in the amidation reaction in step S1 and the amidation reaction in step S2 are separated by an oil-water separator. The amidation reaction in step S1 and the amidation reaction in step S2 are both carried out in a reactor containing an oil-water separator, and the oil-water separator is used to remove the by-product water generated in the reaction. When no more water is separated from the reaction system, the amidation reaction ends. Generally, the time of the amidation reaction in step S1 and the amidation reaction in step S2 is 3-6h.

[0015] The waste oil regenerated fatty acid obtained by hydrolyzing, refining and regenerating waste oil mainly consists of monobasic organic carboxylic acids with 16 to 20 carbon atoms. Preferably, the acid value of the waste oil regenerated fatty acid is 180 to 210 mgKOH / g.

[0016] Preferably, the polyethylene polyamine is selected from one or any combination of diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

[0017] Preferably, the dicarboxylic acid compound is selected from one or any combination of maleic acid, oxalic acid, malonic acid, succinic acid, terephthalic acid and phthalic acid.

[0018] Preferably, the polycarboxylic acid compound is citric acid and / or lactic acid.

[0019] Preferably, the acid anhydride compound is maleic anhydride and / or phthalic anhydride.

[0020] Preferably, the polyethylene polyamine is diethylene triamine, triethylene tetramine or tetraethylene pentamine. Preferably, when the polyethylene polyamine is diethylene triamine, compound A is citric acid, and the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to the polyethylene polyamine is 1:0.8; the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to compound A is 1:1. Preferably, when the polyethylene polyamine is triethylene tetramine, compound A is maleic anhydride, and the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to the polyethylene polyamine is 1:0.8; the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to compound A is 1:1.2. Preferably, when the polyethylene polyamine is tetraethylene pentamine, compound A is oxalic acid, and the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to the polyethylene polyamine is 1:1.2; the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to compound A is 1:1.

[0021] Preferably, the polyethylene polyamine is composed of diethylene triamine and triethylene tetraamine, and the molar ratio of diethylene triamine to triethylene tetraamine is 1: 1. Preferably, the polyethylene polyamine is composed of triethylene tetraamine and tetraethylene pentamine, and the molar ratio of triethylene tetraamine to tetraethylene pentamine is 1:1.

[0022] Preferably, the compound A is citric acid and oxalic acid, and the molar ratio of the citric acid to oxalic acid is 1:1.

[0023] Preferably, when the polyethylene polyamine is composed of diethylenetriamine and triethylenetetramine, compound A is citric acid and oxalic acid, the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to the polyethylene polyamine is 1:1.2; the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to compound A is 1:1.2.

[0024] Preferably, when the polyethylene polyamine is composed of triethylenetetramine and tetraethylenepentamine, compound A is citric acid, the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to the polyethylene polyamine is 1:1; the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to compound A is 1:1.1.

[0025] Preferably, the catalyst used in the amidation reaction in step S1 and the amidation reaction in step S2 is a basic compound. Preferably, the basic compound is an alkali metal hydroxide. For example, the basic compound is sodium hydroxide.

[0026] Preferably, the solvent used in the amidation reaction in step S1 and the amidation reaction in step S2 is an organic solvent. Preferably, the organic solvent is ethylene glycol monobutyl ether.

[0027] In order to simplify the production process, after step S1 is completed, the product of the amidation reaction in step S1 may not be purified, and compound A may be directly added to the system after the amidation reaction in step S1, and then the amidation reaction may be performed, so that the catalyst and organic solvent in step S1 can be reused and production costs can be saved. Preferably, the mass ratio of waste oil regenerated fatty acid to ethylene glycol monobutyl ether is 1:2. Preferably, the mass ratio of NaOH to waste oil regenerated fatty acid is 1:140.

[0028] The technical solution adopted by the oil-based drilling fluid emulsifier of the present invention is:

[0029] An oil-based drilling fluid emulsifier prepared by the above-mentioned method for preparing an oil-based drilling fluid emulsifier.

[0030] When the emulsifier of the present invention is used in oil-based drilling fluid, it can improve the rheological properties of high-density oil-based drilling fluid, reduce the viscosity and shear force of high-density oil-based drilling fluid, speed up drilling speed, and prevent the occurrence of complicated downhole situations such as leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the comparison results of the initial shear force obtained by testing the oil-based drilling fluid obtained by using the emulsifier for the oil-based drilling fluid prepared in the comparative example and Examples 1 to 5;

[0032] Figure 2 It is a schematic diagram of the comparison results of the final shear force obtained by testing the oil-based drilling fluid obtained by using the emulsifier for the oil-based drilling fluid prepared in the comparative example and Examples 1 to 5;

[0033] Figure 3 It is a schematic diagram of the comparison results of the apparent viscosity of the oil-based drilling fluid obtained by testing the oil-based drilling fluid emulsifier prepared in the comparative example and Examples 1 to 5;

[0034] Figure 4 It is a schematic diagram of the comparison results of plastic viscosity of oil-based drilling fluids obtained by testing the emulsifiers for oil-based drilling fluids prepared in the comparative example and in Examples 1 to 5;

[0035] Figure 5 It is a schematic diagram of the comparison results of dynamic shear force obtained from testing the oil-based drilling fluid obtained by using the emulsifier for oil-based drilling fluid prepared in the comparative example and Examples 1 to 5. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below in conjunction with specific implementation methods.

[0037] 1. The specific embodiment of the preparation method of the emulsifier for oil-based drilling fluid of the present invention is as follows:

[0038] Example 1

[0039] The preparation method of the oil-based drilling fluid emulsifier of this embodiment comprises the following steps:

[0040] (1) Dissolve the recycled fatty acid from waste oil (the acid value of the recycled fatty acid from waste oil is 180 mgKOH / g) in an appropriate amount of ethylene glycol monobutyl ether, then put the ethylene glycol monobutyl ether solution containing the recycled fatty acid from waste oil into a three-necked flask equipped with a stirrer, a thermometer and a reflux oil-water separator, start stirring, and the mass ratio of the recycled fatty acid from waste oil to the ethylene glycol monobutyl ether is 1:2;

[0041] (2) During the stirring process, NaOH was added to the three-necked flask until the NaOH was evenly dispersed and the mass ratio of NaOH to the fatty acid regenerated from waste oil was 1:140;

[0042] (3) adding diethylenetriamine to a three-necked flask, heating the reaction system to 160° C. for reflux reaction, removing byproduct water generated in the reaction through an oil-water separator during the reflux reaction, and after reflux reaction for 4 hours, no water is generated in the reaction system, and the molar ratio of carboxyl groups in the fatty acids regenerated from waste oil to diethylenetriamine is 1:0.8;

[0043] (4) Then, citric acid was added to the three-necked flask, and the reaction system was allowed to continue to reflux at 160° C. until no more water was separated from the system. The reaction was stopped, and the system after the reaction was cooled to room temperature to obtain an emulsifier R1 for oil-based drilling fluid, wherein the molar ratio of the carboxyl group in the recycled fatty acid from waste cooking oil to the citric acid was 1:1.

[0044] Example 2

[0045] The method for preparing the emulsifier for oil-based drilling fluid of this embodiment comprises the following steps:

[0046] (1) Dissolve the recycled fatty acid from waste oil (the acid value of the recycled fatty acid from waste oil is 180 mgKOH / g) in an appropriate amount of ethylene glycol monobutyl ether, then put the ethylene glycol monobutyl ether solution containing the recycled fatty acid from waste oil into a three-necked flask equipped with a stirrer, a thermometer and a reflux oil-water separator, start stirring, and the mass ratio of the recycled fatty acid from waste oil to the ethylene glycol monobutyl ether is 1:2;

[0047] (2) During the stirring process, NaOH was added to the three-necked flask until the NaOH was evenly dispersed and the mass ratio of NaOH to the fatty acid regenerated from waste oil was 1:140;

[0048] (3) adding triethylenetetramine to a three-necked flask, heating the reaction system to 180° C. for reflux reaction, removing byproduct water generated in the reaction through an oil-water separator during the reflux reaction, and after reflux reaction for 4 hours, no water is generated in the reaction system, and the molar ratio of carboxyl groups in the fatty acids regenerated from waste oil to triethylenetetramine is 1:0.8;

[0049] (4) Then, maleic anhydride was added to the three-necked flask, and the reaction system was allowed to continue to reflux at 180° C. until no more water was separated from the system. The reaction was stopped, and the system after the reaction was cooled to room temperature to obtain an emulsifier R2 for oil-based drilling fluid. The molar ratio of carboxyl groups in the fatty acid regenerated from waste oil to maleic anhydride was 1:1.2.

[0050] Example 3

[0051] The method for preparing the emulsifier for oil-based drilling fluid of this embodiment comprises the following steps:

[0052] (1) Dissolve the recycled fatty acid from waste oil (the acid value of the recycled fatty acid from waste oil is 195 mgKOH / g) in an appropriate amount of ethylene glycol monobutyl ether, then put the ethylene glycol monobutyl ether solution containing the recycled fatty acid from waste oil into a three-necked flask equipped with a stirrer, a thermometer and a reflux oil-water separator, start stirring, and the mass ratio of the recycled fatty acid from waste oil to the ethylene glycol monobutyl ether is 1:2;

[0053] (2) During the stirring process, NaOH was added to the three-necked flask until the NaOH was evenly dispersed and the mass ratio of NaOH to the fatty acid regenerated from waste oil was 1:140;

[0054] (3) tetraethylenepentamine was added to a three-necked flask, and the reaction system was heated to 200° C. for reflux reaction. During the reflux reaction, water produced as a byproduct was removed by an oil-water separator. After reflux reaction for 4 hours, no water was produced in the reaction system, and the molar ratio of carboxyl groups in the fatty acids regenerated from waste oil to tetraethylenepentamine was 1:1.2;

[0055] (4) Then, oxalic acid was added to the three-necked flask, and the reaction system was allowed to continue to reflux at 200° C. until no more water was separated from the system. The reaction was stopped, and the system after the reaction was cooled to room temperature to obtain an emulsifier R3 for oil-based drilling fluid, wherein the molar ratio of carboxyl groups in the recycled fatty acids from waste cooking oil to oxalic acid was 1:1.

[0056] Example 4

[0057] The preparation method of the oil-based drilling fluid emulsifier of this embodiment comprises the following steps:

[0058] (1) Dissolve the recycled fatty acid from waste oil (the acid value of the recycled fatty acid from waste oil is 210 mgKOH / g) in an appropriate amount of ethylene glycol monobutyl ether, then put the ethylene glycol monobutyl ether solution containing the recycled fatty acid from waste oil into a three-necked flask equipped with a stirrer, a thermometer and a reflux oil-water separator, start stirring, and the mass ratio of the recycled fatty acid from waste oil to the ethylene glycol monobutyl ether is 1:2;

[0059] (2) During the stirring process, NaOH was added to the three-necked flask until the NaOH was evenly dispersed and the mass ratio of NaOH to the fatty acid regenerated from waste oil was 1:140;

[0060] (3) adding diethylenetriamine and triethylenetetramine to a three-necked flask, heating the reaction system to 180° C. for reflux reaction, removing byproduct water generated in the reaction through an oil-water separator during the reflux reaction, and after 5 hours of reflux reaction, no water is generated in the reaction system, and the molar ratio of carboxyl, diethylenetriamine and triethylenetetramine in the fatty acid regenerated from waste oil is 1:0.6:0.6;

[0061] (4) Then, citric acid and oxalic acid were added to the three-necked flask, and the reaction system was allowed to continue to reflux at 160° C. until no more water was separated from the system, and the reaction was stopped. The system after the reaction was cooled to room temperature to obtain an emulsifier R4 for oil-based drilling fluid, wherein the molar ratio of carboxyl, citric acid and oxalic acid in the recycled fatty acid of waste cooking oil was 1:0.6:0.6.

[0062] Example 5

[0063] The method for preparing the emulsifier for oil-based drilling fluid of this embodiment comprises the following steps:

[0064] (1) Dissolve the recycled fatty acid from waste oil (the acid value of the recycled fatty acid from waste oil is 210 mgKOH / g) in an appropriate amount of ethylene glycol monobutyl ether, then put the ethylene glycol monobutyl ether solution containing the recycled fatty acid from waste oil into a three-necked flask equipped with a stirrer, a thermometer and a reflux oil-water separator, start stirring, and the mass ratio of the recycled fatty acid from waste oil to the ethylene glycol monobutyl ether is 1:2;

[0065] (2) During the stirring process, NaOH was added to the three-necked flask until the NaOH was evenly dispersed and the mass ratio of NaOH to the fatty acid regenerated from waste oil was 1:140;

[0066] (3) adding triethylenetetramine and tetraethylenepentamine to a three-necked flask, heating the reaction system to 180° C. for reflux reaction, removing byproduct water generated in the reaction through an oil-water separator during the reflux reaction, and after reflux reaction for 5 hours, no water is generated in the reaction system, and the molar ratio of carboxyl groups, triethylenetetramine and tetraethylenepentamine in the fatty acid regenerated from waste oil is 1:0.5:0.5;

[0067] (4) Then, citric acid was added to the three-necked flask, and the reaction system was allowed to continue to reflux at 160° C. until no more water was separated from the system. The reaction was stopped, and the system after the reaction was cooled to room temperature to obtain an emulsifier R5 for oil-based drilling fluid, wherein the molar ratio of the carboxyl group in the recycled fatty acid from waste cooking oil to the citric acid was 1:1.1.

[0068] Comparative Example

[0069] The preparation method of the oil-based drilling fluid emulsifier of this comparative example comprises the following steps:

[0070] (1) Dissolve 282 g of oleic acid in an appropriate amount of ethylene glycol monobutyl ether, then place the ethylene glycol monobutyl ether solution containing oleic acid into a three-necked flask equipped with a stirrer, a thermometer and a reflux oil-water separator, and start stirring;

[0071] (2) Add 2 g of NaOH to the three-necked flask during stirring until the NaOH is evenly dispersed;

[0072] (3) 103 g of diethylenetriamine was added to a three-necked flask, and the reaction system was heated to 160° C. for reflux reaction. During the reflux reaction, water as a byproduct generated in the reaction was removed by an oil-water separator. After reflux reaction for 4 hours, no water was generated in the reaction system.

[0073] (4) Then, 192 g of citric acid was added to the three-necked flask, and the reaction system was allowed to continue to reflux at 160° C. until no more water was separated from the system. The reaction was stopped, and the system after the reaction was cooled to room temperature to obtain an emulsifier D for oil-based drilling fluid.

[0074] 2. Specific embodiments of the oil-based drilling fluid emulsifier of the present invention are as follows:

[0075] The oil-based drilling fluid emulsifier of this embodiment is prepared by the preparation method of the oil-based drilling fluid emulsifier of any one of Embodiments 1 to 5.

[0076] Experimental example

[0077] The oil-based drilling fluid emulsifiers prepared in Examples 1 to 5 and the comparative example were used as the main oil-based drilling fluid emulsifiers to prepare oil-based drilling fluids, and then the obtained oil-based drilling fluids were added to an aging tank and subjected to rolling aging at 150° C. for 16 hours. After aging, the rheological properties were tested.

[0078] The oil-based drilling fluid is a water-in-oil emulsion, which is prepared by a preparation method comprising the following steps:

[0079] a. Add 2% (based on the mass of the drilling fluid base slurry) of a main oil-based drilling fluid emulsifier, 2.5% (based on the mass of the drilling fluid base slurry) of an auxiliary oil-based drilling fluid emulsifier, and 3% (based on the mass of the drilling fluid base slurry) of a wetting agent to 270 mL of 0# diesel, and stir the mixture at a speed of 12000 r / min for 10 min on a high-speed stirrer to obtain a mixture 1;

[0080] b. Add 30 mL of CaCl to mixture 1. 2 A 25% aqueous solution of the compound was stirred at a speed of 12000 r / min for 10 min on a high-speed stirrer to obtain a mixture 2;

[0081] c. Add 1% (based on the mass of the drilling fluid base slurry) of organic soil, 3% (based on the mass of the drilling fluid base slurry) of CaO and 4% (based on the mass of the drilling fluid base slurry) of fluid loss reducer to the mixture 2, and stir the mixture at a speed of 12000 r / min for 10 min to obtain a mixture 3;

[0082] d. Finally, add 819 g of barite (density of barite is 4.20 g / cm 3 ), mix well, and the density is 2.20g / cm 3 Drilling fluid base slurry.

[0083] In order to evaluate the rheological properties of the oil-based drilling fluids obtained by using emulsifiers for oil-based drilling fluids prepared in different embodiments and comparative examples, the initial shear force, final shear force, Marsh funnel viscosity, apparent viscosity, plastic viscosity and dynamic shear force (yield value) of the oil-based drilling fluids were tested respectively.

[0084] First, the rheological properties of the oil-based drilling fluid were tested using a six-speed rotational viscometer at rotation speeds of 600 r / min, 300 r / min, 200 r / min, 100 r / min, 6 r / min, and 3 r / min, and the readings (in mPa·s) at the corresponding rotation speeds were obtained. and Then the test readings are used to calculate the apparent viscosity (mPa·s), plastic viscosity (mPa·s) and dynamic shear force (Pa) of the oil-based drilling fluid, where the apparent viscosity Plastic viscosity Dynamic shear force

[0085] Then, the oil-based drilling fluid was stirred at a speed of 600 r / min for 10 seconds using a six-speed rotary viscometer, and then tested at a speed of 3 r / min after standing for 10 seconds. The test reading was multiplied by 0.511 to obtain the initial shear force (G10s). Then, the oil-based drilling fluid was stirred at a speed of 600 r / min for 10 seconds using a six-speed rotary viscometer, and then tested at a speed of 3 r / min after standing for 10 minutes. The test reading was multiplied by 0.511 to obtain the final shear force (G10min).

[0086] Finally, the funnel viscosity (FV) of the oil-based drilling fluid was tested using a Marsh funnel. The test method was as follows: first, 1500 mL of the oil-based drilling fluid was placed in a Marsh funnel, and then the time taken for 946 mL of the oil-based drilling fluid to flow out of the Marsh funnel was recorded. The recorded time was the funnel viscosity (FV).

[0087] The rheological properties test results of the oil-based drilling fluids obtained by using the emulsifiers for oil-based drilling fluids prepared in different embodiments and comparative examples are shown in Table 1.

[0088] Table 1 Rheological properties of oil-based drilling fluids obtained by using emulsifiers for oil-based drilling fluids prepared in Examples 1 to 5 and Comparative Examples

[0089]

[0090] It can be seen from Table 1 that the oil-based drilling fluid obtained by using the oil-based drilling fluid emulsifier prepared in the comparative example has high viscosity and shear force after aging, and the initial and final shear forces are very high; while the oil-based drilling fluids obtained by using the oil-based drilling fluid emulsifier prepared in Examples 1 to 5 all show good performance of low viscosity, low shear force, and low initial and final shear forces after aging.

[0091] Then, the test results of the above rheological properties were further analyzed to obtain intuitive comparison results of the rheological properties of the oil-based drilling fluids obtained by using the emulsifiers for oil-based drilling fluids prepared in different embodiments and comparative examples, such as Figures 1 to 5 As shown. Figure 1 It can be seen that compared with the initial shear force obtained by testing the oil-based drilling fluid obtained by the oil-based drilling fluid emulsifier prepared in the comparative example, the initial shear force obtained by testing the oil-based drilling fluid obtained by the oil-based drilling fluid emulsifier prepared in Example 1, Example 2, Example 3, Example 4 and Example 5 decreased by 61.54%, 76.92%, 76.92%, 69.23% and 61.54% respectively; Figure 2 It can be seen that compared with the final shear force obtained by testing the oil-based drilling fluid obtained by the oil-based drilling fluid emulsifier prepared in the comparative example, the final shear force obtained by testing the oil-based drilling fluid obtained by the oil-based drilling fluid emulsifier prepared in Example 1, Example 2, Example 3, Example 4 and Example 5 decreased by 63.16%, 63.16%, 68.42%, 63.16% and 52.63% respectively; Figure 3 It can be seen that compared with the apparent viscosity of the oil-based drilling fluid obtained by the oil-based drilling fluid emulsifier prepared in the comparative example, the apparent viscosity of the oil-based drilling fluid obtained by the oil-based drilling fluid emulsifier prepared in Example 1, Example 2, Example 3, Example 4 and Example 5 decreased by 24.18%, 30.77%, 30.77%, 26.37% and 18.68% respectively; Figure 4 It can be seen that compared with the plastic viscosity of the oil-based drilling fluid obtained by the oil-based drilling fluid emulsifier prepared in the comparative example, the plastic viscosity of the oil-based drilling fluid obtained by the oil-based drilling fluid emulsifier prepared in Example 1, Example 2, Example 3, Example 4 and Example 5 decreased by 18.18%, 25.97%, 24.68%, 19.48% and 12.99% respectively; Figure 5 It can be seen that compared with the dynamic shear force obtained by testing the oil-based drilling fluid obtained by the oil-based drilling fluid emulsifier prepared in the comparative example, the dynamic shear force obtained by testing the oil-based drilling fluid obtained by the oil-based drilling fluid emulsifier prepared in Example 1, Example 2, Example 3, Example 4 and Example 5 decreased by 57.14%, 57.14%, 64.29%, 64.29% and 50.00%, respectively.

Claims

1. A method for preparing an emulsifier for oil-based drilling fluid, characterized in that: The following steps are involved: S1, subjecting waste oil regenerated fatty acids to amidation reaction with polyethylene polyamine; the acid value of the waste oil regenerated fatty acids is 180-210 mgKOH / g; the polyethylene polyamine is selected from one or any combination of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; S2, performing an amidation reaction on the product of the amidation reaction in step S1 and compound A; The compound A is selected from one or any combination of dicarboxylic acid compounds, polycarboxylic acid compounds, and acid anhydride compounds; the molar ratio of the carboxyl group in the waste oil regenerated fatty acid to the polyethylene polyamine is 1:(0.8-1.2); the molar ratio of the polyethylene polyamine to the compound A is (0.8-1.2):(1-1.2); the dicarboxylic acid compound is selected from one or any combination of maleic acid, oxalic acid, malonic acid, succinic acid, terephthalic acid, and phthalic acid; the polycarboxylic acid compound is citric acid and / or lactic acid; and the acid anhydride compound is maleic anhydride and / or phthalic anhydride.

2. The method for preparing an emulsifier for oil-based drilling fluid according to claim 1, characterized in that: The temperature of the amidation reaction in step S1 is 150-200°C.

3. The method for preparing an emulsifier for oil-based drilling fluid according to claim 1, characterized in that: The temperature of the amidation reaction in step S2 is 150-200°C.

4. The method for preparing an emulsifier for oil-based drilling fluid according to any one of claims 1 to 3, characterized in that: The water generated in the amidation reaction in step S1 and the amidation reaction in step S2 is separated by an oil-water separator.

5. An oil-based drilling fluid emulsifier prepared by the method for preparing an oil-based drilling fluid emulsifier according to any one of claims 1 to 4.

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