A lost circulation particle, a method of making and using the same

Abstract

The present application provides a plugging particle, a preparation method and application thereof. Raw materials for preparing the plugging particle include plastic raw materials, a lubricant, a solid dispersant and calcium carbonate particles.

Description

Technical Field

[0001] The invention relates to the field of oil and natural gas exploitation, and in particular to a plugging material used for plugging leaks during a drilling process. Background Art

[0002] At present, the control of lost circulation during drilling is difficult due to inaccurate understanding of the characteristics of leaky formations. In addition, the width of the cracks around the cracks is in a dynamic process of continuous change under stress disturbance. Conventional plugging materials need to have their own particle size strictly matched with the pore size or crack size of the leaky layer to effectively plug cracks with a wider size distribution. After the crack width changes, the formed plugging layer is prone to failure due to its poor adaptability, resulting in poor plugging effect or repeated leakage after successful plugging. Summary of the Invention

[0003] One aspect of the present invention provides plugging particles, the raw materials for preparing the plugging particles include plastic raw materials, lubricants, solid dispersants and calcium carbonate particles.

[0004] In one embodiment, the plastic raw materials are linear low-density polyethylene and thermoplastic rubber.

[0005] In one embodiment, based on the total mass of the plastic raw material as 100%, the content of the linear low-density polyethylene is 10% to 30%, and the content of the thermoplastic rubber is 70% to 90%.

[0006] In one embodiment, the lubricant is at least one of calcium stearate, stearic acid and white oil.

[0007] In one embodiment, the solid dispersant is talc.

[0008] In one embodiment, the calcium carbonate particles have a particle size of 20 mesh to 200 mesh.

[0009] In one embodiment, the calcium carbonate particles have a particle size of 20 mesh to 40 mesh.

[0010] In one embodiment, the calcium carbonate particles have a particle size of 60 mesh to 80 mesh.

[0011] In one embodiment, the calcium carbonate particles have a particle size of 100 mesh to 200 mesh.

[0012] In a specific embodiment, when the particle size of the calcium carbonate particles is 20 mesh to 40 mesh, the particle size of the plugging particles is 5 mesh to 10 mesh.

[0013] In a specific embodiment, when the particle size of the calcium carbonate particles is 60 mesh to 80 mesh, the particle size of the plugging particles is 20 mesh to 40 mesh.

[0014] In a specific embodiment, when the particle size of the calcium carbonate particles is 100 mesh to 200 mesh, the particle size of the plugging particles is 60 mesh to 80 mesh.

[0015] In a specific embodiment, based on 100 parts by mass of the plugging particles, the plastic raw material comprises 37 to 58.5 parts, the lubricant comprises 0.5 to 1 part, the solid dispersant comprises 1 to 2 parts, and the calcium carbonate particles comprise 40 to 60 parts.

[0016] The second aspect of the present invention provides a method for preparing the leak-proof particles, which comprises the following steps:

[0017] 1) heating the calcium carbonate particles to the melting point of the high-melting-point compound in the plastic raw material + (40-50)° C. to obtain heated calcium carbonate particles;

[0018] 2) mixing the heated calcium carbonate particles with the plastic raw material at the melting point temperature + (40-50)° C., adding a lubricant after mixing evenly, adding a solid dispersant after mixing evenly, and mixing evenly to obtain a granular product;

[0019] 3) Cooling, drying, and sieving the granular product to obtain the plugging granules.

[0020] The third aspect of the present invention provides a composition comprising a drilling fluid base slurry and the plugging particles according to any one of the first aspects of the present invention or the plugging particles prepared according to the method according to the second aspect of the present invention.

[0021] In a specific embodiment, the drilling fluid base slurry is a water-based drilling fluid base slurry.

[0022] In a specific embodiment, taking the total mass of the plugging particles as 100%, the plugging particles with a particle size of 5 to 10 mesh account for 98% to 99.5%, the plugging particles with a particle size of 20 to 40 mesh account for 0.4% to 1.2%, and the plugging particles with a particle size of 60 to 80 mesh account for 0.1% to 0.8%.

[0023] The fourth invention provides the use of one of the plugging particles described in any one of the first invention, the plugging particles prepared according to the method described in the second invention, or the composition described in the third invention for plugging leakage when drilling fluid is lost during drilling.

[0024] Beneficial effects of the present invention:

[0025] The plugging particles of the present invention significantly enhance the compressive strength of the plugging particles themselves through the synergistic effect of plastic raw materials, lubricants, solid dispersants and calcium carbonate particles. They are not easily broken under pressure and have reversible deformability and high elasticity. When treating lost circulation, due to their deformability, it is not necessary to overly consider the strict matching of particle size with the pore size of the leaking layer or crack size. Under pressure, they deform into the cracks and produce an effective plugging effect on the cracks. At the same time, when the crack width around the cracks changes continuously under stress disturbance, the high resilience of the plugging material can quickly adapt to the changes in crack width. The formed plugging layer is not easy to fail, which can significantly improve the plugging success rate. The developed plugging particles are deformable under pressure without breaking, can quickly return to their original shape after pressure is removed, have a compressive strength of more than 18MPa, and can be used to form effective plugging for crack widths of 1mm-6mm in the plugging drilling fluid. As the crack width changes, it can quickly adapt to form a new plugging layer, with a leakage loss of less than 600mL and a pressure bearing capacity of 6MPa. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to examples. However, the examples are merely illustrative and do not limit the present invention in any way.

[0027] Anhydrous sodium carbonate and potassium chloride were both chemically pure.

[0028] The bentonite used in the drilling fluid test slurry was purchased from Bohai Drilling Engineering Company.

[0029] Zwitterionic polymer FA367 was purchased from Chengdu Chuanfeng Chemical Co., Ltd.

[0030] Polyanionic cellulose PAC-LV, drilling fluid lubricant RH220, and barite were purchased from Chengdu Xiyou Huawei Technology Co., Ltd.

[0031] Hydrolyzed polyacrylonitrile ammonium salt with a hydrolysis degree of 50% and a relative molecular weight of 10,000 was purchased from Sichuan Xinchuangneng Petroleum Engineering Technology Co., Ltd.

[0032] Preparation of plugging particles

[0033] Example 1

[0034] 1) Heat 60 g of anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh to 200° C.

[0035] 2) quickly transferring the heated anhydrous calcium carbonate particles to a stirrer, starting stirring, and maintaining the anhydrous calcium carbonate particles at a temperature within a range of 190° C. to 200° C.;

[0036] 3) Add 37 g of a plastic raw material of linear low-density polyethylene (melting point temperature 110°C-125°C) and thermoplastic rubber (melting point temperature 130°C-150°C) in a mass ratio of 30:70 to a blender and rapidly stir until uniform. Then, add 1 g of calcium stearate while stirring and stir until uniform. Use an iron rod to break up lumps. Then, add 2 g of talc while stirring and stir until uniform to obtain a granular product.

[0037] 4) The granular product is cooled and dried, and sieved with 5-mesh and 10-mesh standard test sieves, and the granules below the 5-mesh sieve and above the 10-mesh sieve are taken to obtain plugging granules 1#.

[0038] Example 2

[0039] The anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh were replaced with anhydrous calcium carbonate particles with a particle size of 60 to 80 mesh. Other aspects were the same as in Example 1. The particles were sieved with 20-mesh and 40-mesh standard test sieves, and the particles below 20 mesh and above 40 mesh were taken to obtain plugging particles 2#.

[0040] Example 3

[0041] The anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh were replaced with anhydrous calcium carbonate particles with a particle size of 100 to 200 mesh. The other conditions were the same as in Example 1. The particles were sieved with 60-mesh and 80-mesh standard test sieves, and the particles below 60 mesh and above 80 mesh were taken to finally obtain plugging particles 3#.

[0042] Example 4

[0043] 1) heating 49.8 g of anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh to 200° C.;

[0044] 2) quickly transferring the heated anhydrous calcium carbonate particles to a stirrer, starting stirring, and maintaining the anhydrous calcium carbonate particles at a temperature within a range of 190° C. to 200° C.;

[0045] 3) Add 48 g of a plastic raw material of linear low-density polyethylene (melting point temperature 110°C-125°C) and thermoplastic rubber (melting point temperature 130°C-150°C) in a mass ratio of 20:80 to a blender and rapidly stir until uniform. Then, add 0.7 g of calcium stearate while stirring and stir until uniform. Use an iron rod to break up lumps. Then, add 1.5 g of talc while stirring and stir until uniform to obtain a granular product.

[0046] 4) The granular product is cooled and dried, and sieved with 5-mesh and 10-mesh standard test sieves, and the particles below the 5-mesh sieve and above the 10-mesh sieve are taken to obtain plugging granules 4#.

[0047] Example 5

[0048] The anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh were replaced with anhydrous calcium carbonate particles with a particle size of 60 to 80 mesh. The other aspects were the same as in Example 4. The particles were sieved with 20-mesh and 40-mesh standard test sieves, and the particles below 20 mesh and above 40 mesh were taken to finally obtain plugging particles 5#.

[0049] Example 6

[0050] The anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh were replaced with anhydrous calcium carbonate particles with a particle size of 100 to 200 mesh. The other conditions were the same as in Example 4. The particles were sieved with 60-mesh and 80-mesh standard test sieves, and the particles below 60 mesh and above 80 mesh were taken to obtain plugging particles 6#.

[0051] Example 7

[0052] 1) Heat 40 g of anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh to 195° C.

[0053] 2) quickly transferring the heated anhydrous calcium carbonate particles to a stirrer, starting stirring, and maintaining the anhydrous calcium carbonate particles in a range of 190° C. to 195° C.;

[0054] 3) Add 58.5 g of a plastic raw material of linear low-density polyethylene (melting point temperature 110°C-125°C) and thermoplastic rubber (melting point temperature 130°C-150°C) in a mass ratio of 10:90 to a blender and rapidly stir until uniform. Then, add 0.5 g of white oil while stirring and stir until uniform. Use an iron rod to break up lumps. Then, add 1 g of talc while stirring and stir until uniform to obtain a granular product.

[0055] 4) The granular product is cooled and dried, and sieved with 5-mesh and 10-mesh standard test sieves, and the particles below 5 mesh and above 10 mesh are taken to obtain plugging granules 7#.

[0056] Example 8

[0057] The anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh were replaced with anhydrous calcium carbonate particles with a particle size of 60 to 80 mesh. The other methods were the same as those in Example 7. The particles were sieved with 20-mesh and 40-mesh standard test sieves, and the particles below 20 mesh and above 40 mesh were taken to obtain plugging particles 8#.

[0058] Example 9

[0059] The anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh were replaced with anhydrous calcium carbonate particles with a particle size of 100 to 200 mesh. The other conditions were the same as in Example 7. The particles were sieved with 60-mesh and 80-mesh standard test sieves, and the particles below 60 mesh and above 80 mesh were taken to obtain plugging particles 9#.

[0060] Example 10

[0061] 1) Heat 60 g of anhydrous calcium carbonate particles with particle sizes of 20 mesh and 40 mesh to 195° C.

[0062] 2) quickly transferring the heated anhydrous calcium carbonate particles to a stirrer, starting stirring, and maintaining the anhydrous calcium carbonate particles in a range of 190° C. to 195° C.;

[0063] 3) Add 37.5 g of a plastic raw material of linear low-density polyethylene (melting point temperature 110°C-125°C) and thermoplastic rubber (melting point temperature 130°C-150°C) in a mass ratio of 25:75 to a blender and rapidly stir until uniform. Then, add 1 g of white oil while stirring and stir until uniform. Use an iron rod to break up lumps. Then, add 1.5 g of talc while stirring and stir until uniform to obtain a granular product.

[0064] 4) The granular product is cooled and dried, and sieved with 5-mesh and 10-mesh standard test sieves, and the particles below 5 mesh and above 10 mesh are taken to obtain plugging granules 10#.

[0065] Example 11

[0066] The anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh were replaced with anhydrous calcium carbonate particles with a particle size of 60 to 80 mesh. The other methods were the same as those in Example 10. The particles were sieved with 20-mesh and 40-mesh standard test sieves, and the particles below 20 mesh and above 40 mesh were taken to obtain plugging particles 11#.

[0067] Example 12

[0068] The anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh were replaced with anhydrous calcium carbonate particles with a particle size of 100 to 200 mesh. The other conditions were the same as in Example 10. The particles were sieved with 60-mesh and 80-mesh standard test sieves, and the particles below 60 mesh and above 80 mesh were taken to obtain plugging particles 12#.

[0069] Comparative Example 1

[0070] 1) Heat 65 g of anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh to 200° C.

[0071] 2) quickly transferring the heated anhydrous calcium carbonate particles to a stirrer, starting stirring, and maintaining the anhydrous calcium carbonate particles at a temperature within a range of 190° C. to 200° C.;

[0072] 3) Add 33.5 g of a plastic raw material of linear low-density polyethylene (melting point temperature 110°C-125°C) and thermoplastic rubber (melting point temperature 130°C-150°C) in a mass ratio of 30:70 to a blender and rapidly stir until uniform. Then, add 1 g of calcium stearate while stirring and stir until uniform. Use an iron rod to break up lumps. Then, add 2 g of talc while stirring and stir until uniform to obtain a granular product.

[0073] 4) The granular product is cooled and dried, and sieved with 5-mesh and 10-mesh standard test sieves. The granules below the 5-mesh sieve and above the 10-mesh sieve are taken to obtain plugging granules D1#.

[0074] Comparative Example 2

[0075] 1) heating 37 g of anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh to 200° C.;

[0076] 2) quickly transferring the heated anhydrous calcium carbonate particles to a stirrer, starting stirring, and maintaining the anhydrous calcium carbonate particles at a temperature within a range of 190° C. to 200° C.;

[0077] 3) Add 60 g of a plastic raw material of linear low-density polyethylene (melting point temperature 110°C-125°C) and thermoplastic rubber (melting point temperature 130°C-150°C) in a mass ratio of 30:70 to a blender and rapidly stir until uniform. Then, add 1 g of calcium stearate while stirring and stir until uniform. Use an iron rod to break up lumps. Then, add 2 g of talc while stirring and stir until uniform to obtain a granular product.

[0078] 4) The granular product is cooled and dried, and sieved with 5-mesh and 10-mesh standard test sieves. The granules below the 5-mesh sieve and above the 10-mesh sieve are taken to obtain plugging granules D2#.

[0079] Comparative Example 3

[0080] 1) Heat 60 g of anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh to 200° C.

[0081] 2) quickly transferring the heated anhydrous calcium carbonate particles to a stirrer, starting stirring, and maintaining the anhydrous calcium carbonate particles at a temperature within a range of 190° C. to 200° C.;

[0082] 3) Add 37 g of a plastic raw material (linear low-density polyethylene (melting point 110°C-125°C) and thermoplastic rubber (melting point 130°C-150°C) in a 30:70 mass ratio to a blender and rapidly stir until uniform. Then, add 1 g of calcium stearate while stirring and stir until uniform. Use an iron rod to break up any lumps as much as possible. Cool and dry to obtain agglomerated product D3#.

[0083] Comparative Example 4

[0084] 1) Heat 60 g of anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh to 200° C.

[0085] 2) quickly transferring the heated anhydrous calcium carbonate particles to a stirrer, starting stirring, and maintaining the anhydrous calcium carbonate particles at a temperature within a range of 190° C. to 200° C.;

[0086] 3) Add 37 g of a plastic raw material consisting of linear low-density polyethylene (melting point temperature 110°C-125°C) and thermoplastic rubber (melting point temperature 130°C-150°C) in a mass ratio of 30:70 to a blender and rapidly stir until uniform. Then, add 2 g of talc while stirring and stir until uniform. Use an iron rod to break up any lumps as much as possible. Cool and dry to obtain agglomerated product D4#.

[0087] Comparative Example 5

[0088] 1) Heat 60 g of anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh to 200° C.

[0089] 2) quickly transferring the heated anhydrous calcium carbonate particles to a stirrer, starting stirring, and maintaining the anhydrous calcium carbonate particles at a temperature within a range of 190° C. to 200° C.;

[0090] 3) Add 37 g of linear low-density polyethylene (melting point temperature 110°C-125°C) to the blender and stir rapidly until uniform. Then, add 1 g of calcium stearate while stirring and stir until uniform. Use an iron rod to break up lumps. Then, add 2 g of talc while stirring and stir until uniform to obtain a granular product.

[0091] 4) The granular product is cooled and dried, and sieved with 5-mesh and 10-mesh standard test sieves. The granules below the 5-mesh sieve and above the 10-mesh sieve are taken to obtain plugging granules D5#.

[0092] Comparative Example 6

[0093] 1) Heat 60 g of anhydrous calcium carbonate particles with a particle size of 20 to 40 mesh to 200° C.

[0094] 2) quickly transferring the heated anhydrous calcium carbonate particles to a stirrer, starting stirring, and maintaining the anhydrous calcium carbonate particles at a temperature within a range of 190° C. to 200° C.;

[0095] 3) Add 37 g of thermoplastic rubber (melting point temperature 130°C-150°C) to a blender and stir rapidly until uniform. Then, add 1 g of calcium stearate while stirring and stir until uniform. Use an iron rod to break up lumps. Then, add 2 g of talc while stirring and stir until uniform to obtain a granular product.

[0096] 4) The granular product is cooled and dried, and sieved with 5-mesh and 10-mesh standard test sieves. The granules below the 5-mesh sieve and above the 10-mesh sieve are taken to obtain plugging granules D6#.

[0097] Comparative Example 7

[0098] Take anhydrous calcium carbonate particles with a particle size of 5 to 10 mesh and use them as plugging particles D7#.

[0099] Preparation of plugging drilling fluid

[0100] Preparation of water-based drilling fluid slurry:

[0101] Step 1: Measure 400 mL of water, add 0.64 g of anhydrous sodium carbonate and 16 g of bentonite for drilling fluid slurry in sequence under high-speed stirring conditions at (11000±300) r / min, and stir at high speed for 20 minutes. Stop the stirrer halfway and use a glass rod to scrape off the bentonite adhering to the container wall and the stirring rod. Seal and cure at 25℃±3℃ for 24 hours to obtain bentonite-based slurry;

[0102] Step 2: Under high-speed stirring conditions of (11000±300) r / min, 0.8 g of zwitterionic polymer FA367 was added to the bentonite-based slurry in sequence. After complete dissolution, 2.8 g of polyanionic cellulose PAC-LV was added. After complete dissolution, 2.4 g of hydrolyzed polyacrylonitrile ammonium salt with a hydrolysis degree of 50% and a relative molecular mass of 10,000 was added. After complete dissolution, a first mixed solution was obtained.

[0103] Step 3: Add 6 g of drilling fluid lubricant RH220 to the first mixed solution under high-speed stirring conditions of (11000±300) r / min, and stir at high speed for 10 minutes to obtain a second mixed solution;

[0104] Step 4: Add 20 g of KCl to the second mixed solution under high-speed stirring conditions of (11000±300) r / min, and stir at high speed for 30 minutes to obtain a third mixed solution;

[0105] Step 5: Under the condition of low speed stirring at (1200±300) r / min, 486g of a density of 4.3g / cm 3 barite, stirred for 30 minutes, mixed evenly, and obtained water-based drilling fluid slurry.

[0106] Example 13

[0107] 400 g of plugging particles in Example 1#:2#:3# at a mass ratio of 99.3:0.5:0.2 were added to 2 L of water-based drilling fluid slurry, and the mixture was fully stirred and mixed to obtain plugging drilling fluid.

[0108] Example 14

[0109] 400 g of plugging particles prepared in Example 4#:5#:6# at a mass ratio of 99.5:0.4:0.1 were added to 2 L of water-based drilling fluid slurry, and the mixture was stirred and mixed thoroughly to obtain plugging drilling fluid.

[0110] Example 15

[0111] 400 g of plugging particles prepared in Example 7#:8#:9# at a mass ratio of 98:1.2:0.8 were added to 2 L of water-based drilling fluid slurry, and the mixture was stirred and mixed thoroughly to obtain plugging drilling fluid.

[0112] Example 16

[0113] 400 g of plugging particles prepared in Example 1#:5#:9# at a mass ratio of 99.3:0.5:0.2 were added to 2 L of water-based drilling fluid slurry, and the mixture was stirred and mixed thoroughly to obtain plugging drilling fluid.

[0114] Example 17

[0115] 400 g of plugging particles prepared in Example 4#:8#:3# at a mass ratio of 99.5:0.4:0.1 were added to 2 L of water-based drilling fluid slurry, and the mixture was stirred and mixed thoroughly to obtain plugging drilling fluid.

[0116] Comparative Example 8

[0117] 400 g of plugging particles prepared in Example 1#:2#:3# at a mass ratio of 97:2:1 were added to 2 L of water-based drilling fluid slurry, and the mixture was stirred and mixed thoroughly to obtain plugging drilling fluid.

[0118] Comparative Example 9

[0119] 400 g of plugging particles prepared in Example 4#:5#:6# at a mass ratio of 99.5:0.2:0.3 were added to 2 L of water-based drilling fluid slurry, and the mixture was stirred and mixed thoroughly to obtain plugging drilling fluid.

[0120] Comparative Example 10

[0121] 400 g of calcium carbonate particles with a mass ratio of 5 to 10 mesh, 20 to 40 mesh and 60 to 80 mesh of 99.3:0.5:0.2 were added to 2 L of water-based drilling fluid base slurry, and the mixture was fully stirred and mixed to obtain a plugging drilling fluid.

[0122] Performance measurement

[0123] (1) Density measurement

[0124] The density of the plugging particles was measured according to the apparent density test method in 10.4 of SY / T 5108-2014, "Test Methods for Proppants for Hydraulic Fracturing and Gravel Packing." The results are shown in Table 1.

[0125] (2) Particle size determination

[0126] For Example 1, Example 4, Example 7, Example 10, Comparative Example 1, Comparative Example 2, Comparative Example 5 and Comparative Example 6, assemble a 5-mesh upper standard test sieve and a 10-mesh lower standard test sieve and a bottom plate, weigh the mass of the granular product in step 3) of each Example or Comparative Example, record it as m, unit g, add a top cover and place it on a vibrating sieve. After vibrating for 10 minutes, weigh the mass of the plugging particles on the lower standard test sieve, record it as m1, unit g, and the mass percentage of the plugging particles from 5 mesh to 10 mesh (recorded as C) is calculated by the following formula:

[0127] C=(m1 / m)×100

[0128] The results are shown in Table 1.

[0129] For Example 2, Example 5, Example 8 and Example 11, a 20-mesh upper standard test sieve, a 40-mesh lower standard test sieve and a base plate were assembled, and then the same operating process as above was used to finally calculate the mass percentage of the 20-mesh to 40-mesh plugging particles. The results are shown in Table 1.

[0130] For Example 3, Example 6, Example 9 and Example 12, a 60-mesh upper standard test sieve, an 80-mesh lower standard test sieve and a base plate were assembled, and then the same operating process as above was used to finally calculate the mass percentage of the 60-mesh to 80-mesh plugging particles. The results are shown in Table 1.

[0131] Table 1 Performance evaluation of plugging particles

[0132]

[0133] (3) Compression resistance test

[0134] The plugging particles were pressurized using a WHY-300 microcomputer-controlled fully automatic pressure testing machine from Shanghai Hualong Testing Instrument Co., Ltd. to measure their compressive strength. After complete pressure relief, the particles were observed to see whether they could recover their original shape within 1 minute. The results are shown in Table 2.

[0135] The mass percentage of the plugging particles in the lower standard test sieve after pressure was determined according to method (2). The results are shown in Table 2.

[0136] Table 2 Evaluation of the compressive performance of plugging particles

[0137]

[0138] According to the results in Tables 1 and 2, the particle size of the product of Comparative Example 1 is uneven due to the inappropriate dosage of each component, and the plugging particles of Comparative Example 2 have relatively low compressive strength. The products of Comparative Examples 3 and 4 have poor dispersibility and form clumps, making them unusable for subsequent plugging. The plugging particles of Comparative Example 5 cannot return to their original shape after pressure is applied, and because they cannot return to their original shape after pressure is applied, their particles are flattened. This not only causes the particle size value to increase, so that the mass percentage of the sample in the lower sieve after pressure is 100%, but more importantly, the particles are easily flattened, which is not conducive to plugging. The plugging particles of Comparative Example 6 have poor compressive resistance. The plugging particles of Comparative Example 7 can withstand a pressure of only 0.2 MPa. The plugging particles prepared in Examples 1 to 12 of the present invention are uniform in size, can effectively combine plastic raw materials with calcium carbonate, and the plugging particles formed are uniform and free of clumps. They have good compressive resistance and can be deformed without breaking under pressure. They have a compressive strength of more than 18 MPa and can quickly return to their original shape after the pressure is removed.

[0139] (4) Evaluation of plugging effect

[0140] Determination method: The device with patent number ZL 201610943279.6, "An Adjustable Seam Width Leakage Plugging Instrument", is used to evaluate the plugging effect. A total leakage volume greater than 650 mL is considered to be unsatisfactory in terms of plugging effect.

[0141] Step 1: Stir the plugging drilling fluid for 10 minutes, pour it into the sleeve of the plugging instrument, and assemble the plugging instrument.

[0142] Step 2: Adjust the gap width of the leak stopper to 1mm.

[0143] Step 3: Start the timer and increase the pressure at a rate of 14 kPa / s until the pressure reaches 6 MPa. Maintain this pressure for 10 minutes and record the volume of the plugging drilling fluid that flows out. If the plugging fails before the pressure increases to 6 MPa, the plugging fails. The test is terminated when the plugging drilling fluid flows out of the casing and the pressure at which the plugging failure occurs is recorded.

[0144] Step 4: Adjust the pressure to 1 MPa, and slowly adjust the slit width of the plugging instrument to 3 mm, 5 mm, and 6 mm in sequence, and record the volume of the plugging drilling fluid that flows out. If the plugging fails before the pressure increases to 6 MPa, the plugging fails, and the test is terminated when the plugging drilling fluid flows out of the casing. Record the pressure when the plugging failure occurs and the cumulative loss volume of the plugging drilling fluid.

[0145] Table 3 Leakage plugging effect evaluation table

[0146]

[0147]

[0148] According to the results of Table 3, Comparative Examples 8 and 9 have unreasonable plugging particle size distributions, and the prepared plugging drilling fluids have poor plugging effects and large leakage under pressure and crack width changes. Comparative Example 10 uses calcium carbonate particles to prepare plugging drilling fluids according to a reasonable particle size distribution. Because calcium carbonate particles do not have deformability and elasticity, under pressure and crack width changes, leakage is large. After the crack width changes, it cannot adapt quickly and the plugging fails. The plugging drilling fluids prepared using the plugging particle ratios of Examples 13 to 17 can effectively plug the crack width of 1mm-6mm, and due to the deformability and elasticity of the plugging particles of the present invention themselves, as the crack width changes, they can quickly adapt to form a new plugging layer, and the compression resistance can reach 6MPa, with a cumulative leakage loss of less than 600mL.

[0149] In summary, through comparative analysis of the embodiments and comparative examples, the technical effect produced by the plugging particles of the present invention is better, which is the result of the reasonable distribution ratio of each component in the plugging particles of the present invention and the synergistic effect.

[0150] Although the present invention has been described with reference to specific embodiments, those skilled in the art will appreciate that various modifications may be made without departing from the true spirit and scope of the invention. Furthermore, the subject matter, spirit, and scope of the invention may be modified in various ways to adapt to specific circumstances, materials, combinations of materials, and methods. All such modifications are intended to be within the scope of the claims.

Claims

1. A plugging particle, the raw materials for its preparation include plastic raw materials, lubricant, solid dispersant and calcium carbonate particles; The plastic raw materials are linear low-density polyethylene and thermoplastic rubber; The particle size of the calcium carbonate particles is 20 mesh to 200 mesh; Based on 100 parts by mass of the plugging particles, the plastic raw material comprises 37 to 58.5 parts, the lubricant comprises 0.5 to 1 part, the solid dispersant comprises 1 to 2 parts, and the calcium carbonate particles comprise 40 to 60 parts.

2. The plugging particles according to claim 1, characterized in that: Based on the total mass of the plastic raw material as 100%, the content of the linear low-density polyethylene is 10% to 30%, and the content of the thermoplastic rubber is 70% to 90%.

3. The plugging particles according to claim 1, characterized in that: The lubricant is at least one of calcium stearate, stearic acid and white oil.

4. The plugging particles according to claim 1, characterized in that: The solid dispersant is talc.

5. The plugging particles according to claim 1, characterized in that: The particle size of the calcium carbonate particles is 20 mesh to 40 mesh.

6. The plugging particles according to claim 1, characterized in that: The particle size of the calcium carbonate particles is 60 mesh to 80 mesh.

7. The plugging particles according to claim 1, characterized in that: The particle size of the calcium carbonate particles is 100 mesh to 200 mesh.

8. The plugging particles according to claim 5, characterized in that: When the particle size of the calcium carbonate particles is 20 mesh to 40 mesh, the particle size of the plugging particles is 5 mesh to 10 mesh.

9. The plugging particles according to claim 6, characterized in that: When the particle size of the calcium carbonate particles is 60 mesh to 80 mesh, the particle size of the plugging particles is 20 mesh to 40 mesh.

10. The plugging particles according to claim 7, characterized in that: When the particle size of the calcium carbonate particles is 100 mesh to 200 mesh, the particle size of the plugging particles is 60 mesh to 80 mesh.

11. A method for preparing the plugging particles according to any one of claims 1 to 10, comprising the following steps: 1) Heating the calcium carbonate particles to the melting point of the high-melting-point compound in the plastic raw material + (40-50)°C to obtain heated calcium carbonate particles; 2) mixing the heated calcium carbonate particles with the plastic raw material at the melting point temperature + (40-50)°C, adding a lubricant after mixing evenly, adding a solid dispersant after mixing evenly, and mixing evenly to obtain a granular product; 3) Cooling, drying, and sieving the granular product to obtain the plugging granules.

12. A composition comprising a drilling fluid base slurry and the lost circulation plugging particles according to any one of claims 1 to 10 or the lost circulation plugging particles prepared according to the method of claim 11.

13. The composition according to claim 12, characterized in that The drilling fluid base slurry is a water-based drilling fluid base slurry; and / or Taking the total mass of the plugging particles as 100%, the plugging particles with a particle size of 5 to 10 mesh account for 98% to 99.5%, the plugging particles with a particle size of 20 to 40 mesh account for 0.4% to 1.2%, and the plugging particles with a particle size of 60 to 80 mesh account for 0.1% to 0.8%.

14. Use of the plugging particles according to any one of claims 1 to 10, the plugging particles prepared according to the method of claim 11, or the composition according to claim 12 or 13 for plugging leakage of drilling fluid during drilling.

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