A drilling fluid suitable for high-voltage electric pulse rock-breaking drilling and a preparation method thereof

Abstract

The present invention provides a drilling fluid suitable for high-voltage electric pulse rock-breaking drilling, wherein the raw materials include a base oil phase, an aqueous phase, a primary emulsifier, an auxiliary emulsifier, organic soil, a shearing agent, a fluid loss reducer, lime, and a weighting material, and the raw materials include: 53 parts to 94 parts of the base oil phase, 6 parts to 47 parts of the aqueous phase, 4 parts to 11 parts of the primary emulsifier, 3 parts to 9 parts of the auxiliary emulsifier, 3 parts to 8 parts of the organic soil, 2 parts to 6 parts of the shearing agent, 3 parts to 9 parts of the fluid loss reducer, 1 part to 4 parts of lime, and 20 parts to 400 parts of the weighting material. The drilling fluid prepared by the present invention meets the requirements of high resistivity, high electrical strength, high temperature stability during high-voltage discharge, rapid recovery performance after breakdown, and the performance of completing conventional drilling fluids; at the same time, it is not easy to be broken down during the discharge process, and the insulation capacity is avoided to be lost, so that the rheological properties during drilling and the electrical insulation performance are met, and the drilling fluid is suitable for high-voltage electric pulse rock-breaking drilling.

Description

Technical Field

[0001] The invention relates to the technical field of deep drilling and hard rock drilling, and in particular to a drilling fluid suitable for high-voltage electric pulse rock breaking drilling and a preparation method thereof. Background Art

[0002] High-voltage electric pulse rock-breaking drilling technology is a new type of rock-breaking drilling technology. Its basic principle is that when the voltage rise time is less than 500ns, the rock breaks down before the water, a plasma channel is formed in the rock, and the electric energy is deposited in the rock plasma channel and an electric explosion occurs, which destroys the rock in the form of tensile damage. Under normal conditions, high-voltage electric pulse discharge rock-breaking drilling only requires 100 to 300 J / cm 3 The energy ratio requirement is 1000 J / cm2, while in mechanical rotary drilling, it needs to reach 1000 J / cm2. 3 Drilling requires drilling fluid, which is the blood of drilling engineering and plays multiple roles, such as carrying rock cuttings and maintaining the stability of the hole wall. At present, most of the research on high-voltage electric pulse rock breaking drilling uses tap water, deionized water and insulating oil as insulating media. However, these media cannot play the role that drilling fluid should play in the actual drilling process, especially in deep well drilling.

[0003] The drilling fluid used in high-voltage electric pulse rock-breaking drilling technology needs to meet the requirements of high resistivity, high electrical strength, high temperature stability during high-voltage discharge, rapid recovery performance after breakdown, and the performance of conventional drilling fluid. However, the tap water commonly used in indoor experiments currently has a resistivity of zero and is easily broken down during the discharge process, thus losing its insulation ability. Deionized water is easily contaminated, which reduces its resistivity. Insulating oil has good insulation properties but its viscosity is too high and it cannot carry rock cuttings, so it cannot meet the requirements in practical applications.

[0004] Drilling fluids are classified into water-based drilling fluids and oil-based drilling fluids, and water-based drilling fluids are obviously not suitable for high-voltage electric pulse rock-breaking drilling processes. Oil-based drilling fluids use oil as a continuous phase and water as a dispersed phase, which can meet both insulation performance and drilling requirements. In addition, environmental protection is now increasingly valued. Therefore, the present invention uses coal-to-white oil with an aromatic content of 0.014% and a main component of alkanes (content greater than 94%) as a base oil to prepare a drilling fluid suitable for high-voltage electric pulse rock-breaking drilling. Compared with ordinary white oil, the low aromatic content of coal-to-white oil can greatly reduce pollution to the environment. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a drilling fluid suitable for high-voltage electric pulse rock breaking drilling and a preparation method thereof.

[0006] The embodiment of the present invention provides a drilling fluid suitable for high-voltage electric pulse rock breaking drilling, wherein the raw materials include a base oil phase, an aqueous phase, a primary emulsifier, an auxiliary emulsifier, organic soil, a shearing agent, a fluid loss reducer, lime, and a weighting material, which are calculated by weight:

[0007] 53-94 parts of base oil phase, 6-47 parts of water phase, 4-11 parts of primary emulsifier, 3-9 parts of auxiliary emulsifier, 3-8 parts of organic soil, 2-6 parts of shearing agent, 3-9 parts of filtration reducer, 1-4 parts of lime, and 20-400 parts of weighting material.

[0008] Furthermore, the fluid loss reducer is organic lignite, which contains several polar groups.

[0009] Furthermore, the base oil phase is one of the coal-to-oil white oils W1-60, W2-80, W2-100, and W2-TB produced by Ningxia Coal-to-Oil Company.

[0010] Furthermore, the organic soil is modified bentonite BP500A produced by Zhejiang Fenghong New Materials Co., Ltd.

[0011] Furthermore, the weighting material is one or both of 800-mesh calcium carbonate powder and barite powder.

[0012] Furthermore, the barite powder is barium sulfate powder, and the lime is calcium oxide.

[0013] Furthermore, the aqueous phase is one of a calcium chloride solution or a sodium chloride solution, and the mass fraction of the aqueous phase is 20% to 25%.

[0014] Furthermore, the primary emulsifier is BZ-OPE, and the secondary emulsifier is BZ-OSE.

[0015] Furthermore, the density of the drilling fluid is 1.0 to 2.1 g / cm 3 .

[0016] The invention also includes a method for preparing the drilling fluid suitable for high-voltage electric pulse rock breaking drilling, comprising the following steps:

[0017] S1, adding a primary emulsifier and a secondary emulsifier to the base oil phase in sequence, and stirring continuously at a speed of 8000 rpm for 10 minutes;

[0018] S2, adding one quarter of the mass of organic soil and a cutting agent to the base oil phase in sequence, and stirring continuously at a speed of 8000 rpm for 20 minutes;

[0019] S3, adding half the mass of water phase to the base oil phase, and stirring continuously at 10000 rpm for 10 minutes;

[0020] S4, adding one quarter of the mass of organic soil and a shearing agent to the base oil phase in sequence, and stirring continuously at a rotation speed of 10000 rpm for 20 minutes;

[0021] S5, adding half the mass of water phase to the base oil phase, and stirring continuously at 10000 rpm for 10-20 minutes;

[0022] S6, adding one quarter of the mass of organic soil and a shearing agent to the base oil phase in sequence, and stirring continuously at a rotation speed of 10000 rpm for 20 minutes;

[0023] S7, adding one quarter of the mass of organic soil and a shearing agent to the base oil phase in sequence, and stirring continuously at a rotation speed of 10000 rpm for 20 minutes;

[0024] S8, adding a fluid loss reducer to the base oil phase, and continuously stirring at a rotation speed of 10000 rpm for 20 minutes;

[0025] S9, adding lime to the base oil phase, and continuously stirring at a rotation speed of 10000 rpm for 20 minutes;

[0026] S10, continue to add weighting material and continue stirring at 10000 rpm for 30 minutes to obtain a density of 1.0-2.1 g / cm 3 The drilling fluid.

[0027] The beneficial effects brought about by the technical solution provided by the embodiments of the present invention are as follows: the present invention provides a drilling fluid suitable for high-voltage electric pulse rock breaking drilling and a preparation method, the prepared drilling fluid meets the requirements of high resistivity, high electrical strength, high temperature stability during high-voltage discharge, rapid recovery performance after breakdown, and completes the performance of conventional drilling fluid; at the same time, it is not easy to be broken down during the discharge process, avoiding loss of insulation ability, satisfying both the rheological properties during drilling and the electrical insulation performance, and being suitable for high-voltage electric pulse rock breaking drilling. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a flow chart of a method for preparing drilling fluid suitable for high-voltage electric pulse rock breaking drilling. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0030] Example 1

[0031] This embodiment provides a density of 1.2g / cm 3, an electric pulse rock breaking drilling fluid with an oil-water ratio of 80:20 is prepared from the following raw materials in parts by weight: 75 parts of a base oil phase, 7 parts of a primary emulsifier, 6 parts of an auxiliary emulsifier, 6 parts of organic soil, 3 parts of a shearing agent, 6 parts of a fluid loss reducer, 2.5 parts of lime, 25 parts of an aqueous phase, and 247 parts of a weighting material; in this embodiment, the base oil phase is one of coal-to-oil white oils W1-60, W2-80, W2-100, and W2-TB produced by Ningxia Coal-to-Oil Company, and the specific model can be selected according to the needs of actual working conditions, the primary emulsifier is BZ-OPE, the auxiliary emulsifier is BZ-OSE, the organic soil is modified bentonite BP500A produced by Zhejiang Fenghong New Materials Co., Ltd., the fluid loss reducer is organic lignite, which contains several polar groups; the lime is calcium oxide; the aqueous phase is a calcium chloride aqueous solution with a mass concentration of 20%; the weighting material is 800-mesh calcium carbonate powder.

[0032] The specific drilling fluid configuration process includes the following steps:

[0033] S1, placing 75 parts by mass of coal-to-white oil in a high-stirring cup, then adding 7 parts by mass of a primary emulsifier and 6 parts by mass of a secondary emulsifier to the coal-to-white oil in sequence, and stirring continuously at a speed of 8000 rpm for 10 minutes;

[0034] S2, then add 1.5 parts by mass of organic soil and 0.75 parts by mass of shearing agent to the coal-to-white oil in the high-stirring cup, and continue stirring at 8000 rpm for 20 minutes;

[0035] S3, then add 12.5 parts by mass of calcium chloride aqueous solution to the coal-to-white oil in the high stirring cup, and continue stirring at a speed of 10000 rpm for 10 minutes;

[0036] S4, then add 1.5 parts by mass of organic soil and 0.75 parts by mass of cutting agent to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0037] S5, then add 12.5 parts by mass of calcium chloride aqueous solution to the coal-to-white oil in the high stirring cup, and continue stirring at a speed of 10000 rpm for 10-20 minutes; in this embodiment, the stirring time is 15 minutes;

[0038] S6, then add 1.5 parts by mass of organic soil and 0.75 parts by mass of shearing agent to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0039] S7, then add 1.5 parts by mass of organic soil and 0.75 parts by mass of cutting agent to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0040] S8, then add 6 parts by mass of filtrate reducer to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0041] S9, then add 2.5 parts by mass of calcium oxide to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10,000 rpm for 20 minutes;

[0042] S10, finally, add 247 parts by mass of 800-mesh calcium carbonate powder and continue stirring at 10,000 rpm for 30 minutes to obtain a density of 1.2 g / cm 3 of drilling fluid.

[0043] The rheological properties of the drilling fluid obtained above were compared and analyzed before and after aging (as shown in Table 1 below). Table 1 shows the changes in the rheological properties of the drilling fluid in Example 1 before and after aging:

[0044] Table 1 Rheological properties before and after aging

[0045]

[0046] In the table, PV is plastic viscosity; AV is apparent viscosity; YP is dynamic shear force; ES is demulsification voltage; FL is HTHP It is the high temperature and high pressure filtration loss.

[0047] The data in Table 1 show that before and after aging, the plastic viscosity, apparent viscosity, and high-temperature and high-pressure filtration loss of the drilling fluid in Example 1 are all improved, and the dynamic cutting force, initial cutting / final cutting, and demulsification voltage are all reduced. The performance of the drilling fluid is significantly improved, which can meet both the insulation performance and the drilling requirements, and is suitable for high-voltage electric pulse rock breaking drilling.

[0048] Example 2

[0049] This embodiment provides a density of 1.1g / cm 3, an electric pulse rock breaking drilling fluid with an oil-water ratio of 95:5 is prepared from the following raw materials in parts by weight: 94 parts of a base oil phase, 5 parts of a primary emulsifier, 4 parts of an auxiliary emulsifier, 8 parts of organic soil, 5 parts of a shearing agent, 3 parts of a fluid loss reducer, 1 part of lime, 6 parts of an aqueous phase, and 390 parts of a weighting material; in this embodiment, the base oil phase is one of coal-to-oil white oils W1-60, W2-80, W2-100, and W2-TB produced by Ningxia Coal-to-Oil Company, and the specific model can be selected according to the needs of actual working conditions, the primary emulsifier is BZ-OPE, the auxiliary emulsifier is BZ-OSE, the organic soil is modified bentonite BP500A produced by Zhejiang Fenghong New Materials Co., Ltd., the fluid loss reducer is organic lignite, which contains several polar groups; the lime is calcium oxide; the aqueous phase is a calcium chloride aqueous solution with a mass concentration of 20%; the weighting material is 800-mesh calcium carbonate powder.

[0050] The specific drilling fluid configuration process includes the following steps:

[0051] S1, placing 94 parts by mass of coal-to-white oil in a high stirring cup, then adding 5 parts by mass of a primary emulsifier and 4 parts by mass of a secondary emulsifier to the coal-to-white oil in sequence, and stirring continuously at a speed of 8000 rpm for 10 minutes;

[0052] S2, then add 2 parts by mass of organic soil and 1.25 parts by mass of cutting agent to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 8000 rpm for 20 minutes;

[0053] S3, then add 3 parts by mass of calcium chloride aqueous solution to the coal-to-white oil in the high stirring cup, and continue stirring at a speed of 10000 rpm for 10 minutes;

[0054] S4, then add 2 parts by mass of organic soil and 1.25 parts by mass of cutting agent to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0055] S5, then add 3 parts by mass of calcium chloride aqueous solution to the coal-to-white oil in the high stirring cup, and continue stirring at a speed of 10000 rpm for 10-20 minutes; in this embodiment, the stirring time is 15 minutes;

[0056] S6, then add 2 parts by mass of organic soil and 1.25 parts by mass of cutting agent to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0057] S7, then add 2 parts by mass of organic soil and 1.25 parts by mass of cutting agent to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0058] S8, then add 3 parts by mass of filtrate reducer to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0059] S9, then add 1 part by mass of calcium oxide to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0060] S10, finally, add 390 parts by mass of 800-mesh calcium carbonate powder and continue stirring at 10,000 rpm for 30 minutes to obtain a density of 1.1 g / cm 3 of drilling fluid.

[0061] The rheological properties of the drilling fluid obtained above were compared and analyzed before and after aging (as shown in Table 2 below). Table 2 shows the changes in the rheological properties of the drilling fluid in Example 2 before and after aging:

[0062] Table 2 Rheological properties before and after aging

[0063]

[0064] In the table, PV is plastic viscosity; AV is apparent viscosity; YP is dynamic shear force; ES is demulsification voltage; FL is HTHP It is the high temperature and high pressure filtration loss.

[0065] The data in Table 2 show that before and after aging, the plastic viscosity, apparent viscosity, and high-temperature and high-pressure filtration loss of the drilling fluid in Example 2 are all improved, and the dynamic cutting force, initial cutting / final cutting, and demulsification voltage are all reduced. The performance of the drilling fluid is significantly improved, which can meet both the insulation performance and the drilling requirements, and is suitable for high-voltage electric pulse rock breaking drilling.

[0066] Example 3

[0067] This embodiment provides a density of 1.2g / cm 3, an electric pulse rock breaking drilling fluid with an oil-water ratio of 60:40 is prepared from the following raw materials in parts by weight: 53 parts of a base oil phase, 11 parts of a primary emulsifier, 7 parts of an auxiliary emulsifier, 2 parts of organic soil, 1.5 parts of a shearing agent, 9 parts of a fluid loss reducer, 3 parts of lime, 47 parts of an aqueous phase, and 20 parts of a weighting material; in this embodiment, the base oil phase is one of coal-to-oil white oils W1-60, W2-80, W2-100, and W2-TB produced by Ningxia Coal-to-Oil Company, and the specific model can be selected according to the needs of actual working conditions, the primary emulsifier is BZ-OPE, the auxiliary emulsifier is BZ-OSE, the organic soil is modified bentonite BP500A produced by Zhejiang Fenghong New Materials Co., Ltd., the fluid loss reducer is organic lignite, which contains several polar groups; the lime is calcium oxide; the aqueous phase is a calcium chloride aqueous solution with a mass concentration of 20%; the weighting material is 800-mesh calcium carbonate powder.

[0068] The specific drilling fluid configuration process includes the following steps:

[0069] S1, placing 53 parts by mass of coal-to-white oil in a high stirring cup, then adding 11 parts by mass of a primary emulsifier and 7 parts by mass of a secondary emulsifier to the coal-to-white oil in sequence, and stirring continuously at a speed of 8000 rpm for 10 minutes;

[0070] S2, then add 0.5 parts by mass of organic soil and 0.375 parts by mass of shearing agent to the coal-to-white oil in the high-stirring cup, and continue stirring at 8000 rpm for 20 minutes;

[0071] S3, then add 23.5 parts by mass of calcium chloride aqueous solution into the coal-to-white oil in the high stirring cup, and continue stirring at a speed of 10000 rpm for 10 minutes;

[0072] S4, then add 0.5 parts by mass of organic soil and 0.375 parts by mass of cutting agent to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0073] S5, then add 23.5 parts by mass of calcium chloride aqueous solution to the coal-to-white oil in the high stirring cup, and continue stirring at a speed of 10000 rpm for 10-20 minutes; in this embodiment, the stirring time is 15 minutes;

[0074] S6, then add 0.5 parts by mass of organic soil and 0.375 parts by mass of cutting agent to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0075] S7, then add 0.5 parts by mass of organic soil and 0.375 parts by mass of shearing agent to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0076] S8, then add 9 parts by mass of filtrate reducer to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10000 rpm for 20 minutes;

[0077] S9, then add 3 parts by mass of calcium oxide to the coal-to-white oil in the high-stirring cup, and continue stirring at a speed of 10,000 rpm for 20 minutes;

[0078] S10, finally, add 20 parts by mass of 800-mesh calcium carbonate powder and continue stirring at 10,000 rpm for 30 minutes to obtain a density of 1.2 g / cm 3 of drilling fluid.

[0079] The rheological properties of the drilling fluid obtained above were compared and analyzed before and after aging (as shown in Table 3 below). Table 3 shows the changes in the rheological properties of the drilling fluid in Example 3 before and after aging:

[0080] Table 3 Rheological properties before and after aging

[0081]

[0082] In the table, PV is plastic viscosity; AV is apparent viscosity; YP is dynamic shear force; ES is demulsification voltage; FL is HTHP It is the high temperature and high pressure filtration loss.

[0083] The data in Table 3 show that before and after aging, the plastic viscosity, apparent viscosity, and high-temperature and high-pressure filtration loss of the drilling fluid in Example 3 are all improved, and the dynamic cutting force, initial cutting / final cutting, and demulsification voltage are all reduced. The performance of the drilling fluid is significantly improved, which can meet both the insulation performance and the drilling requirements, and is suitable for high-voltage electric pulse rock breaking drilling.

[0084] The raw materials described in Example 1, Example 2, and Example 3 are all products sold on the market. When purchased, they are strictly inspected according to industry standards or enterprise standards, and only qualified ones can be used.

[0085] 1. Optimization of emulsifier

[0086] 3% emulsifier (3% each of primary emulsifier and auxiliary emulsifier) ​​was added to 320ml drilling fluid base fluid (coal-based white oil), and stirred at high speed for 40 minutes. Subsequently, 2% organic soil was added, and stirred at 8000rpm for 10min. 2% calcium oxide was added, and stirred at high speed for 20min. Then 80ml of 20% calcium chloride aqueous solution was slowly added, and stirred at high speed for 1h to prepare a low-density drilling fluid. The fluid was rolled and aged at 150°C for 16h, and the demulsification voltage and rheological parameters of the synthetic-based drilling fluid were measured at 50°C to evaluate the emulsification effect of different emulsifiers. The measurement results are shown in Table 4 below.

[0087] Table 4 Comparison of emulsification effects of different emulsifiers

[0088]

[0089] From the data in Table 4, it can be seen that by comparing the emulsions formed by several different emulsifiers, the emulsifier (BZ-OPE+BZ-OSE) studied in this study has a higher demulsification voltage and is better than other emulsifiers.

[0090] 2. Optimization of organic soil

[0091] Slowly add 6g±0.01g of organic soil to 300ml of drilling fluid base liquid (coal-based white oil), then stir at high speed for 30min at a speed of 10000rpm, then use a measuring cylinder to measure 100ml of the test solution, start timing at the same time, record the volume V of the base oil precipitated on the upper part of the measuring cylinder after 90min, and then calculate the colloid rate, colloid rate = (100-V) / 100x100%.

[0092] Table 5 Colloid rate

[0093] Organic soil Sodium montmorillonite BZ-OC BP500A Gel formation rate (%) 0 0 97

[0094] From the data in Table 5, it can be seen that the colloid rate of modified bentonite BP500A produced by Zhejiang Fenghong New Materials Co., Ltd. reaches 97%, which is better than other organic soils.

[0095] 3. Drilling fluid electrical performance test

[0096] Since the drilling fluid of the present invention is used for high-pressure pulse rock-breaking drilling, it is necessary to test the relevant electrical insulation properties of the drilling fluid. Therefore, the drilling fluid in Example 1 is taken as an example for performance testing.

[0097] According to the measurement standards of dielectric loss factor and relative dielectric constant, professional instruments are used to measure according to the prescribed steps at a temperature of 25°C; at the same time, according to the relevant provisions of the power industry standards, a resistivity meter is used to measure the volume resistivity according to the prescribed steps at a temperature of 25°C. Therefore, the drilling fluid performance of Example 1 is:

[0098] Table 6 Electrical properties of drilling fluid in Example 1

[0099]

[0100] Furthermore, the performance of tap water and insulating oil currently used as drilling fluids is compared with the performance of the drilling fluid in Example 1, as shown in Table 7 below:

[0101] Table 7 Performance comparison

[0102]

[0103] According to the data in Table 7, it can be seen that the drilling fluid in Example 1 has better advantages in dielectric loss factor and relative dielectric constant, and also always meets the actual working conditions in terms of volume resistivity.

[0104] Furthermore, the drilling fluid in the present invention needs to be used in rock breaking conditions, so a rock breaking experiment is carried out on the drilling fluid in Example 1 to measure the peak current discharged in the drilling fluid during rock breaking; a needle-plate electrode discharge structure is adopted in the rock breaking experiment, and tap water, the drilling fluid in Example 1, and high-voltage insulating oil are used as insulating media respectively, and the broken rocks used are sandstone with a diameter of 50 mm and a height of 50 mm and granite with a diameter of 50 mm and a height of 25 mm.

[0105] The discharge rock breaking experiment uses an electric voltage of 120KV. Under the same discharge times, the peak currents of the two rocks when broken in three different media are recorded respectively. In the sandstone breaking experiment, tap water and the drilling fluid prepared in Example 1 are discharged seven times to cause sandstone to break, and insulating oil is broken four times. The following Table 8 shows the peak currents of the three substances when they are discharged in the sandstone breaking experiment:

[0106] Table 8 Peak current of discharge during sandstone crushing experiment

[0107]

[0108] In the granite experiment, the discharge when tap water is used as the medium can never break the granite, and no current is detected in the experiment. When the drilling fluid and insulating oil prepared in Example 1 are used as the medium, the granite can be broken by discharging once. Table 9 shows the peak current when the drilling fluid and insulating oil prepared in Example 1 are used as the medium:

[0109] Table 9 Peak current of discharge in granite crushing experiment

[0110] —— Drilling Fluid Insulating oil Peak current (KA) 5.8 5.56

[0111] According to the data in Tables 8 and 9 above, it can be known that the drilling fluid prepared in the present invention can meet both the rheological properties during drilling and the electrical insulation properties, and can be used as an insulating flushing fluid for high-voltage electric pulse rock-breaking drilling.

[0112] In this document, the directional words such as front, back, top, and bottom are defined by the positions of the components in the drawings and the positions of the components relative to each other, and are only for the sake of clarity and convenience in expressing the technical solution. It should be understood that the use of the directional words should not limit the scope of protection claimed in this application.

[0113] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0114] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A drilling fluid suitable for high-voltage electric pulse rock-breaking drilling, the raw materials of which include base oil phase, water phase, primary emulsifier, auxiliary emulsifier, organic soil, shear enhancer, fluid loss reducer, lime, and weighting material. It is characterized in that The parts by weight include: 53-94 parts of base oil phase, 6-47 parts of water phase, 4-11 parts of primary emulsifier, 3-9 parts of auxiliary emulsifier, 3-8 parts of organic soil, 2-6 parts of shearing agent, 3-9 parts of fluid loss reducer, 1-4 parts of lime, 20-400 parts of weighting material; The base oil phase is one of the coal-to-liquid white oils W1-60, W2-80, W2-100 and W2-TB produced by Ningxia Coal-to-Liquid Company; The organic soil is modified bentonite BP500A produced by Zhejiang Fenghong New Materials Co., Ltd. The primary emulsifier is BZ-OPE, and the secondary emulsifier is BZ-OSE.

2. A drilling fluid suitable for high-voltage electric pulse rock breaking drilling as claimed in claim 1, Features: The fluid loss reducer is organic lignite, which contains several polar groups.

3. A drilling fluid suitable for high-voltage electric pulse rock breaking drilling as claimed in claim 1, Features: The weighting material is one or both of 800-mesh calcium carbonate powder and barite powder.

4. A drilling fluid suitable for high-voltage electric pulse rock breaking drilling as claimed in claim 3, Features: The barite powder is barium sulfate powder, and the lime is calcium oxide.

5. A drilling fluid suitable for high-voltage electric pulse rock breaking drilling as claimed in claim 1, Features: The aqueous phase is one of a calcium chloride solution or a sodium chloride solution, and the mass fraction of the aqueous phase is 20% to 25%.

6. A drilling fluid suitable for high-voltage electric pulse rock breaking drilling as claimed in claim 1, Features: The density of the drilling fluid is 1.0-2.1 g / cm 3 .

7. A method for preparing a drilling fluid suitable for high-voltage electric pulse rock breaking drilling as claimed in any one of claims 1 to 6, It is characterized in that The following steps are involved: S1, adding a primary emulsifier and a secondary emulsifier to the base oil phase in sequence, and stirring continuously at a speed of 8000 rpm for 10 minutes; S2, adding one quarter of the mass of organic soil and a cutting agent to the base oil phase in sequence, and stirring continuously at a speed of 8000 rpm for 20 minutes; S3, adding half the mass of water phase to the base oil phase, and stirring continuously at 10000 rpm for 10 minutes; S4, adding one quarter of the mass of organic soil and a shearing agent to the base oil phase in sequence, and stirring continuously at a rotation speed of 10000 rpm for 20 minutes; S5, adding half the mass of water phase to the base oil phase, and stirring continuously at 10000 rpm for 10-20 minutes; S6, adding one quarter of the mass of organic soil and a shearing agent to the base oil phase in sequence, and stirring continuously at a rotation speed of 10000 rpm for 20 minutes; S7, adding one quarter of the mass of organic soil and a shearing agent to the base oil phase in sequence, and stirring continuously at a rotation speed of 10000 rpm for 20 minutes; S8, adding a fluid loss reducer to the base oil phase, and continuously stirring at a rotation speed of 10000 rpm for 20 minutes; S9, adding lime to the base oil phase, and continuously stirring at a rotation speed of 10000 rpm for 20 minutes; S10, continue to add weighting material, and continue stirring at a rotation speed of 10000 rpm for 30 minutes to obtain the drilling fluid with a density of 1.0 to 2.1 g / cm³.

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