While-drilling composite plugging agent for oil-based drilling fluid as well as preparation method and application of while-drilling composite plugging agent

Abstract

The invention provides a while-drilling composite plugging agent for an oil-based drilling fluid as well as a preparation method and application of the while-drilling composite plugging agent. The while-drilling composite plugging agent for the oil-based drilling fluid comprises an oil absorption expansion solid-phase particle material, an oleophylic elastic deformation material, an oleophylic modified bridging plugging material and an asphalt material in specific parts. Through the synergistic effect of the four materials, the while-drilling composite plugging agent for the oil-based drilling fluid is good in compatibility with the oil-based drilling fluid, uniform in particle size and wide in particle size range, it can be ensured that in the drilling process, the oil-based drilling fluid and the oil-based drilling fluid can be well mixed, the efficiency of leakage prevention and plugging is effectively improved, and the drilling efficiency of the oil-based drilling fluid is improved. And meanwhile, the rheological property of the oil-based drilling fluid is not influenced, microfractured leakage channels in different shapes can be well plugged, a good plugging-while-drilling effect is achieved, and the success rate of plugging-while-drilling is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas drilling fluids, and particularly relates to a composite lost circulation material for oil-based drilling fluids while drilling, a preparation method thereof, and an application thereof. Background Art

[0002] In the exploration and development of unconventional oil and gas reservoirs such as shale oil and gas / tight oil and gas, situations such as lost circulation, wellbore instability, wellbore collapse, and stuck pipe often occur, resulting in extended drilling time, increased drilling costs, and even wellbore abandonment, causing huge economic losses. An oil-based drilling fluid refers to a drilling fluid that uses a base oil as the continuous phase and exhibits certain properties similar to oils under certain conditions. Compared with water-based drilling fluids, oil-based drilling fluids have advantages such as good temperature resistance, strong resistance to salt and calcium pollution, good lubricity, good corrosion resistance, and little influence from external factors, and are currently the best choice for drilling fluids used in unconventional oil and gas reservoirs such as shale oil and gas / tight oil and gas.

[0003] Leakage or lost circulation often occurs during the drilling process of oil-based drilling fluids. If not treated in time, it may lead to accidents and complications such as wellbore instability and overflow, seriously endangering the safety of drilling operations, and also interfering with logging and misleading the discovery of oil and gas resources; at the same time, the cost of oil-based drilling fluids is high, and lost circulation will cause relatively large economic losses. Therefore, the use of lost circulation materials for oil-based drilling fluids is crucial.

[0004] CN106634898A discloses a composite lost circulation material for oil-based drilling fluids while drilling, a preparation method thereof, and an application thereof. The lost circulation material includes: sheet materials with a fineness less than 200 mesh; granular materials with a fineness less than 200 mesh; fibrous materials with a fineness less than 100 mesh; elastic materials with a fineness less than 100 mesh; the weight ratio of the sheet materials, granular materials, fibrous materials, and elastic materials is (2 - 5):(4 - 8):(2 - 5):(0.5 - 3); the composite lost circulation material for oil-based drilling fluids provided by this invention can improve the plugging effect on sand beds and small cracks. When the lost circulation material while drilling is added to the oil-based drilling fluid, in a 20 - 40 mesh sand bed, the penetration depth of the filtrate is less than 3 cm; when plugging a 0.5 mm crack, the pressure-bearing capacity is greater than 7 MPa.

[0005] CN105524600A discloses a lost circulation material for oil-based drilling fluid while drilling. By mass fraction, it includes the following components: 20-30 parts of deformable particles, 10-15 parts of elastic deformation particles, 5-10 parts of light bridging particles, and 40-70 parts of calcium carbonate. The lost circulation material for oil-based drilling fluid provided by this invention uses all inert materials, which has good compatibility and environmental friendliness with oil-based drilling fluid; it has good filtration loss reduction effect, can form a dense mud cake on the wellbore wall to prevent the occurrence of permeable lost circulation; it adopts the principle of rigid-flexible combination of plugging with rigid materials, deformation particles and elastic materials to effectively prevent the backflow and re-leakage of lost circulation materials and the occurrence of induced fractures during tripping.

[0006] CN108314996A discloses a lost circulation material for drilling fluid that can reduce the lost circulation volume while ensuring the demulsification voltage of oil-based drilling fluid. The lost circulation material for drilling fluid includes: rigid polybutyl ester in the form of flakes or particles with a mesh size of 4-200, mica flakes with a mesh size of 4-200, calcium carbonate, and polypropylene fiber. The mass percentages of each component are: rigid polybutyl ester in the form of flakes or particles with a mesh size of 4-200: 30-60%, mica flakes with a mesh size of 4-200: 30-60%, calcium carbonate: 4-12%, polypropylene fiber: 1-3%. The lost circulation material for drilling fluid has a moderate self-density and acid solubility rate, strong compressive ability, and small lost circulation volume; it has good application effects; it is non-toxic and has no environmental pollution, and is suitable for both water-based and oil-based muds; it has no adverse effects on other properties of oil-based drilling fluid and has good compatibility; it has a continuous and stable effect for a long time and is an excellent lost circulation material.

[0007] CN111303845A discloses a preparation method of a lost circulation material for oil-based drilling fluid while drilling. By mass percentage, 20-30% of oil-wettable flaky materials, 5-10% of rigid particle materials, 40-60% of oil-absorbing and swelling type particle materials, and 10-25% of oil-wettable composite fiber materials are uniformly mixed, dried, stirred and crushed, and the particle size is screened so that 70% of the lost circulation material for while drilling has a particle size of 0.075-0.5 mm. The main component is an oil-absorbing and swelling material, which can swell well in white oil and diesel, and is squeezed into micro-fractures under pressure difference and then absorbs oil and swells, thereby filling the fractured formation and improving the success rate of lost circulation while drilling; it has good strength and elasticity, has high compressive strength and shear resistance, and can deform and fill fractures in the formation.

[0008] However, the lost circulation materials while drilling for oil-based drilling fluids provided in the above-mentioned existing technologies all have the following problems: (1) Most of the above-mentioned lost circulation materials while drilling for oil-based drilling fluids are hydrophilic and oleophobic materials, with poor compatibility with oil-based drilling fluids, thus having a greater impact on the rheology of oil-based drilling fluids. After long-term use, they are prone to fermentation and deterioration, resulting in a reduction in the lost circulation prevention effect and easy recurrence of lost circulation; (2) Most of the above-mentioned oil-based lost circulation materials are rigid materials, without elastic deformability and oil absorption and swelling properties, with poor adaptability to cracks, unable to effectively seal formation pores, and unable to effectively achieve the lost circulation prevention effect; (3) The above-mentioned oil-based lost circulation materials have poor temperature resistance. As time increases in the formation, the pressure-bearing capacity gradually decreases, resulting in a worse lost circulation prevention effect; (4) The addition amount of the lost circulation material while drilling for the above-mentioned oil-based lost circulation materials is high, with poor economic adaptability.

[0009] Therefore, in order to solve at least one of the above problems, it is urgent to develop a lost circulation composite agent while drilling for oil-based drilling fluids with good compatibility with oil-based drilling fluids, strong temperature resistance, high pressure-bearing capacity, and strong plugging ability. Summary of the Invention

[0010] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a lost circulation composite agent while drilling for oil-based drilling fluids, its preparation method and application. By selecting four materials, namely oil absorption and swelling solid particle materials, oleophilic elastic deformation materials, oleophilic modified bridging plugging materials, and asphalt materials, for synergistic cooperation, the obtained lost circulation composite agent while drilling for oil-based drilling fluids has good compatibility with oil-based drilling fluids, uniform particle size and a relatively wide particle size range, can better plug micro-fracture lost circulation channels of different shapes, has a good lost circulation prevention effect while drilling, not only improves the lost circulation prevention and plugging efficiency, but also improves the success rate of lost circulation prevention while drilling.

[0011] To achieve this purpose, the present invention adopts the following technical solutions:

[0012] In the first aspect, the present invention provides a lost circulation composite agent while drilling for oil-based drilling fluids, and the lost circulation composite agent while drilling for oil-based drilling fluids comprises the following components by weight:

[0013]

[0014]

[0015] The drilling-fluid-loss-compensating agent for oil-based drilling fluid provided by the present invention comprises specific parts by weight of oil-absorbing and swelling solid particle materials, oil-loving elastic deformation materials, oil-loving modified bridging and plugging materials and asphalt materials. Among them, the particle size of the oil-absorbing and swelling solid particle materials can change after oil absorption and swelling, and different pore spaces and fractures can be plugged. The oil-loving elastic deformation materials will deform under the action of differential pressure to adapt to fractures of different shapes and sizes. The oil-loving modified bridging and plugging materials can play a good bridging role to form a spatial framework and improve the success rate of plugging. The asphalt materials can effectively plug micro-fractures and improve the pressure-bearing capacity. By the synergistic effect of the above four materials, the drilling-fluid-loss-compensating agent for oil-based drilling fluid obtained has good compatibility with the oil-based drilling fluid, uniform particle size and a relatively wide particle size range, ensuring that it can enter and occupy the target area during drilling, effectively improving the efficiency of leakage prevention and plugging. At the same time, since the composite plugging agent is an oil-loving material, it will not only not affect the rheology of the oil-based drilling fluid, but also can better plug micro-fracture leakage channels of different shapes, having a good function of plugging during drilling, which is beneficial to improving the success rate of plugging during drilling.

[0016] In addition, the raw materials of the drilling-fluid-loss-compensating agent for oil-based drilling fluid provided by the present invention are widely sourced and low in cost. At the same time, it also has the advantages of relatively simple preparation method, low requirements for equipment, environmental friendliness and safe use.

[0017] Among them, the oil-absorbing and swelling solid particle materials can be 28 parts by weight, 30.5 parts by weight, 31 parts by weight, 31.5 parts by weight, 32 parts by weight, 32.5 parts by weight, 33 parts by weight, 33.5 parts by weight, 34 parts by weight or 34.5 parts by weight, etc.

[0018] The oil-loving elastic deformation materials can be 10.5 parts by weight, 11 parts by weight, 11.5 parts by weight, 12 parts by weight, 12.5 parts by weight, 13 parts by weight, 13.5 parts by weight, 14 parts by weight or 14.5 parts by weight, etc.

[0019] The oil-loving modified bridging and plugging materials can be 32 parts by weight, 34 parts by weight, 36 parts by weight, 38 parts by weight, 40 parts by weight, 42 parts by weight, 44 parts by weight, 46 parts by weight or 48 parts by weight, etc.

[0020] The asphalt materials can be 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight or 14 parts by weight, etc.

[0021] Preferably, at least 80% of the particle size of the drilling-fluid-loss-compensating agent for oil-based drilling fluid is 0.1 - 0.8 mm, such as 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm or 0.7 mm, etc.

[0022] It should be noted that the statement "at least 80% of the particle size of the compound lost circulation material for oil-based drilling fluid while drilling is 0.1 - 0.8 mm" means that in the compound lost circulation material for oil-based drilling fluid while drilling, the weight ratio of the compound lost circulation material for oil-based drilling fluid with a particle size of 0.1 - 0.8 mm is not less than 80%. Similar expressions mentioned below all represent the same meaning.

[0023] Preferably, the oil-absorbing and swelling solid particle material includes oil-absorbing rubber and olefin-based oil-absorbing resin.

[0024] Preferably, the oil-absorbing rubber includes ethylene-propylene-diene monomer rubber and / or polyacrylate rubber.

[0025] Preferably, the mass ratio of the oil-absorbing rubber to the olefin-based oil-absorbing resin is (3 - 5):(6 - 5), such as 3:7, 4:6 or 5:5, etc.

[0026] Preferably, at least 80% of the particle size of the oil-absorbing and swelling solid particle material is 0.2 - 0.5 mm, such as 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm or 0.45 mm, etc.

[0027] Preferably, the oil-loving elastic deformation material includes polyacrylamide-based elastic microsphere material.

[0028] Preferably, the preparation raw materials of the polyacrylamide-based elastic microsphere material include monomers, initiators, cross-linking agents, dispersants and reinforcing agents.

[0029] Preferably, the preparation method of the polyacrylamide-based elastic microsphere material includes: reacting monomers, initiators, cross-linking agents, dispersants and reinforcing agents to obtain the polyacrylamide-based elastic microsphere material.

[0030] Preferably, at least 80% of the particle size of the oil-loving elastic deformation material is 0.5 - 0.8 mm, such as 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm or 0.75 mm, etc.

[0031] Preferably, the oil-loving modified bridging plugging material is obtained by modifying the bridging plugging material.

[0032] As a preferred technical solution of the present invention, by modifying the bridging plugging material, its surface can be changed from hydrophilic to oil-loving or nearly oil-loving, and thus its compatibility with the oil-based drilling fluid will be better, reducing the influence of adding the lost circulation material on the rheology of the oil-based drilling fluid.

[0033] Preferably, the lipophilic modified bridging plugging material is prepared by the following method, which includes: placing the bridging plugging material in a fluidized bed for fluidization operation, and at 50-65 °C, uniformly spraying a surface modifier on the surface of the bridging plugging material through a tangential spraying device to obtain the lipophilic modified bridging plugging material.

[0034] Preferably, the surface modifier includes alkylolamide derivatives, fatty acid derivatives, dimethyldihexadecylammonium chloride, and methacrylate polyethylene glycol copolymer.

[0035] Among them, the alkylolamide derivative can specifically be the alkylolamide derivative wetting agent GW-WET (Great Wall Drilling Engineering Company Limited, CNPC); the fatty acid derivative can specifically be the fatty acid derivative ZFS-1 (Jiyuan Tiancheng Chemical Co., Ltd.); the dimethyldihexadecylammonium chloride and the methacrylate polyethylene glycol copolymer can be selected as conventional commercially available products.

[0036] Preferably, the surface modifier comprises the following components by weight:

[0037]

[0038] Among them, the alkylolamide derivative can be 2.1 parts by weight, 2.2 parts by weight, 2.3 parts by weight, 2.4 parts by weight, 2.5 parts by weight, 2.6 parts by weight, 2.7 parts by weight, 2.8 parts by weight, or 2.9 parts by weight, etc.

[0039] The fatty acid derivative can be 3.2 parts by weight, 3.4 parts by weight, 3.6 parts by weight, 3.8 parts by weight, 4 parts by weight, 4.2 parts by weight, 4.4 parts by weight, 4.6 parts by weight, or 4.8 parts by weight, etc.

[0040] The dimethyldihexadecylammonium chloride can be 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.2 parts by weight, 2.4 parts by weight, 2.6 parts by weight, or 2.8 parts by weight, etc.

[0041] The methacrylate polyethylene glycol copolymer can be 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.2 parts by weight, 2.4 parts by weight, 2.6 parts by weight, or 2.8 parts by weight, etc.

[0042] Preferably, the bridging plugging material includes sheet-like filler materials, rigid bridging materials, and composite fiber materials.

[0043] Preferably, the bridging plugging material comprises the following components by weight:

[0044] Sheet-like filler materials 20-30 parts by weight;

[0045] 40 - 50 parts by weight of rigid bridging material;

[0046] 30 - 40 parts by weight of composite fiber material.

[0047] Among them, the sheet filling material can be 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight or 29 parts by weight, etc.

[0048] The rigid bridging material can be 42 parts by weight, 44 parts by weight, 46 parts by weight or 48 parts by weight, etc.

[0049] The composite fiber material can be 32 parts by weight, 34 parts by weight, 36 parts by weight or 38 parts by weight, etc.

[0050] Preferably, the sheet filling material includes any one or a combination of at least two of calcite, mica flakes or glassine paper.

[0051] Preferably, the particle size of at least 80% of the sheet filling material is 0.2 - 0.6 mm, such as 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm or 0.55 mm, etc.

[0052] Preferably, the rigid bridging material includes any one or a combination of at least two of marble, ceramsite or limestone.

[0053] Preferably, the particle size of at least 80% of the rigid bridging material is 0.1 - 0.8 mm, such as 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm or 0.7 mm, etc.

[0054] Preferably, the composite fiber material includes any one or a combination of at least two of cottonseed hulls, asbestos powder or paper fiber.

[0055] Preferably, the particle size of at least 80% of the composite fiber material is 0.1 - 0.5 mm, such as 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm or 0.4 mm, etc.

[0056] Preferably, the particle size of at least 70% of the lipophilic modified bridging plugging material is 0.1 - 0.8 mm, such as 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm or 0.7 mm, etc.

[0057] Preferably, the asphalt - based material includes oil - soluble oxidized asphalt and / or quaternary ammonium salt - type modified asphalt.

[0058] In a second aspect, the present invention provides a preparation method of a drilling fluid-loss control agent for oil-based drilling fluid as described in the first aspect. The preparation method includes: mixing an oil-absorbing and swelling solid particle material, an oil-loving elastic deformation material, an oil-loving modified bridging and plugging material, and an asphalt material, and performing crushing and particle size screening to obtain the drilling fluid-loss control agent for oil-based drilling fluid.

[0059] In a third aspect, the present invention provides an oil-based drilling fluid, which includes a base drilling fluid and the drilling fluid-loss control agent for oil-based drilling fluid as described in the first aspect.

[0060] Preferably, based on 100 parts by weight of the base drilling fluid, the dosage of the drilling fluid-loss control agent for oil-based drilling fluid is 5 to 10 parts by weight, such as 6 parts by weight, 7 parts by weight, 8 parts by weight, or 9 parts by weight, etc.

[0061] In a fourth aspect, the present invention provides an application of the drilling fluid-loss control agent for oil-based drilling fluid as described in the first aspect or the oil-based drilling fluid as described in the third aspect in drilling.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] (1) The drilling fluid-loss control agent for oil-based drilling fluid provided by the present invention includes specific amounts of an oil-absorbing and swelling solid particle material, an oil-loving elastic deformation material, an oil-loving modified bridging and plugging material, and an asphalt material, has good compatibility with the oil-based drilling fluid, and can be used while drilling without affecting the drilling efficiency.

[0064] (2) The drilling fluid-loss control agent for oil-based drilling fluid provided by the present invention can achieve leak prevention and plugging effects at temperatures of 100 to 200 °C, and can be applied to leak prevention and plugging operations under different depths and temperature conditions.

[0065] (3) The drilling fluid-loss control agent for oil-based drilling fluid provided by the present invention includes an oil-absorbing and swelling solid particle material, an oil-loving elastic deformation material, an oil-loving modified bridging and plugging material, and an asphalt material. Under the action of differential pressure, the above materials improve the compressive strength and shear resistance through bridging, stuffing, oil-absorbing and swelling plugging, and elastic deformation. When filling fractured formations, good plugging and leak prevention effects can be achieved on pores, throats, etc. with a relatively large size distribution range, reducing the filtration loss of the oil-based drilling fluid and the occurrence of leakage.

[0066] (4) The drilling fluid-loss control agent for oil-based drilling fluid provided by the present invention has a wide application range and good plugging effect.

[0067] (5) The lost circulation composite plugging agent for oil-based drilling fluids provided by the present invention is a lipophilic material. While not affecting the rheology of oil-based drilling fluids, it can better plug micro-fracture lost circulation channels of different shapes, has good anti-loss plugging and lost circulation plugging while drilling functions, is conducive to improving the success rate of lost circulation plugging while drilling, and the plugging effect will not weaken over time.

[0068] (6) The lost circulation composite plugging agent for oil-based drilling fluids provided by the present invention has the advantages of wide raw material sources, environmental friendliness, excellent performance, and safe use. The preparation method is relatively simple, has low requirements for equipment, and the product quality is controllable. Specific Embodiments

[0069] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0070] Some raw material information involved in the specific embodiments of the present invention is as follows:

[0071] (1) Alkyl alcohol amide derivative: Specifically, the alkyl alcohol amide derivative wetting agent GW-WET, China National Petroleum Corporation Great Wall Drilling Engineering Company;

[0072] (2) Fatty acid derivative: Specifically, the fatty acid derivative ZFS-1, Jiyuan Tiancheng Chemical Co., Ltd.;

[0073] (3) Methacrylic acid polyester ethylene glycol copolymer: Shanghai Tuoyang Biotechnology Co., Ltd., MAC-PEG-PLGA;

[0074] (4) Ethylene propylene diene monomer rubber: Jilin Petrochemical Company, China National Petroleum Corporation, J-3092E;

[0075] (5) Polyacrylate oil-absorbing rubber: Wushi Ma Technology (Chongqing) Co., Ltd.;

[0076] (6) Olefin-based oil-absorbing resin: Southwest Petroleum University, SWXD-1;

[0077] (7) Oxidized asphalt: Anhui Luhai Petroleum Auxiliary Technology Co., Ltd., LH-OFL;

[0078] (8) Quaternary ammonium salt-modified asphalt: Anhui Luhai Petroleum Auxiliary Technology Co., Ltd.;

[0079] (9) Emulsifier: Tiancheng Chemical Co., Ltd.

[0080] Preparation Example 1

[0081] A polyacrylamide-based elastic microsphere material, and its preparation method includes: dissolving 15 g of acrylamide monomer, 0.5 g of ammonium bisulfite, 0.8 g of hydroxyethyl methacrylate, 0.8 g of calcium carbonate, and 1.2 g of graphite in 80 mL of pure water, and then dropping the solution into 120 mL of castor oil, and reacting at 55 °C for 45 min to obtain the polyacrylamide-based elastic microsphere material.

[0082] Preparation Example 2

[0083] A lipophilic modified bridging plugging material, and its preparation raw materials include the following components by weight:

[0084]

[0085] Among them, the flaky filler is composed of calcite, mica flakes, and glassine paper with a mass ratio of 3:4:1, the rigid bridging material is composed of marble, ceramsite, and limestone with a mass ratio of 2.5:4:3.5, and the composite fiber material is composed of cottonseed hulls, asbestos powder, and paper fiber with a mass ratio of 2:3:5;

[0086] The preparation method of the lipophilic modified bridging plugging material provided in this preparation example includes the following steps:

[0087] (1) Mix the flaky filler, the rigid bridging material, and the composite fiber material evenly to obtain a bridging plugging material; mix alkylolamide derivatives, fatty acid derivatives, dimethyldipalmitylammonium chloride, and methacrylate polyethylene glycol copolymer to obtain a surface modifier;

[0088] (2) Place the bridging plugging material obtained in step (1) in a fluidized bed for fluidization operation, and at 55 °C, evenly spray the surface modifier obtained in step (1) on the surface of the bridging plugging material through a tangential spray device to obtain the lipophilic modified bridging plugging material.

[0089] Preparation Example 3

[0090] A lipophilic modified bridging plugging material, and its preparation raw materials include the following components by weight:

[0091]

[0092] Among them, the flaky filler is composed of calcite, mica flakes, and glassine paper with a mass ratio of 3:4:1, the rigid bridging material is composed of marble, ceramsite, and limestone with a mass ratio of 2.5:4:3.5, and the composite fiber material is composed of cottonseed hulls, asbestos powder, and paper fiber with a mass ratio of 2:3:5;

[0093] The lipophilic modified bridging plugging material provided in this preparation example is the same as that in Preparation Example 2.

[0094] Preparation Example 4

[0095] A lipophilic modified bridging plugging material, and its preparation raw materials include the following components by weight:

[0096]

[0097]

[0098] Among them, the flaky filling material is composed of calcite, mica flakes and glassine paper with a mass ratio of 3:4:1, the rigid bridging material is composed of marble, ceramsite and limestone with a mass ratio of 2.5:4:3.5, and the composite fiber material is composed of cottonseed hulls, asbestos powder and paper fibers with a mass ratio of 2:3:5;

[0099] The lipophilic modified bridging plugging material provided in this preparation example is the same as that in Preparation Example 2.

[0100] Preparation Example 5

[0101] A lipophilic modified bridging plugging material, and its preparation raw materials include the following components by weight:

[0102]

[0103] Among them, the flaky filling material is composed of calcite, mica flakes and glassine paper with a mass ratio of 3:4:1, the rigid bridging material is composed of marble, ceramsite and limestone with a mass ratio of 2.5:4:3.5, and the composite fiber material is composed of cottonseed hulls, asbestos powder and paper fibers with a mass ratio of 2:3:5;

[0104] The lipophilic modified bridging plugging material provided in this preparation example is the same as that in Preparation Example 2.

[0105] Example 1

[0106] A drilling fluid used with a compound lost circulation material, which includes the following components by weight:

[0107]

[0108] Among them, the oil absorption and swelling solid particle material is composed of ethylene propylene diene monomer, polyacrylate oil absorption rubber and olefin oil absorption resin with a mass ratio of 2:2:6; the lipophilic elastic deformation material is the polyacrylamide elastic microsphere material provided in Preparation Example 1; the asphalt material is composed of oxidized asphalt and modified asphalt with a mass ratio of 6:4; the lipophilic modified bridging plugging material is from Preparation Example 2;

[0109] The preparation method of the drilling-fluid-invading composite plugging agent for oil-based drilling fluid provided by this embodiment includes: uniformly mixing an oil-absorbing and swelling solid particle material, an oil-loving elastic deformation material, an asphalt material, and an oil-loving modified bridging plugging material, and performing crushing and particle size screening to obtain a drilling-fluid-invading composite plugging agent for oil-based drilling fluid with at least 80% of the particle size ranging from 0.1 to 0.8 mm.

[0110] Example 2

[0111] A drilling-fluid-invading composite plugging agent for oil-based drilling fluid, which comprises the following components by weight:

[0112]

[0113] Among them, the oil-absorbing and swelling solid particle material is composed of ethylene propylene diene monomer rubber and olefin-based oil-absorbing resin with a mass ratio of 4:6; the oil-loving elastic deformation material is the polyacrylamide-based elastic microsphere material provided by Preparation Example 1; the asphalt material is composed of oxidized asphalt and modified asphalt with a mass ratio of 5:5; the oil-loving modified bridging plugging material is derived from Preparation Example 3;

[0114] The preparation method of the drilling-fluid-invading composite plugging agent for oil-based drilling fluid provided by this embodiment is the same as that of Example 1.

[0115] Example 3

[0116] A drilling-fluid-invading composite plugging agent for oil-based drilling fluid, which comprises the following components by weight:

[0117]

[0118] Among them, the oil-absorbing and swelling solid particle material is composed of polyacrylate oil-absorbing rubber and olefin-based oil-absorbing resin with a mass ratio of 4:6; the oil-loving elastic deformation material is the polyacrylamide-based elastic microsphere material provided by Preparation Example 1; the asphalt material is composed of oxidized asphalt and modified asphalt with a mass ratio of 8:2; the oil-loving modified bridging plugging material is derived from Preparation Example 4;

[0119] The preparation method of the drilling-fluid-invading composite plugging agent for oil-based drilling fluid provided by this embodiment is the same as that of Example 1.

[0120] Example 4

[0121] A drilling-fluid-invading composite plugging agent for oil-based drilling fluid, which comprises the following components by weight:

[0122]

[0123] Among them, the oil-absorbing and swelling solid particle material is composed of ethylene-propylene-diene monomer rubber, polyacrylate oil-absorbing rubber and olefin oil-absorbing resin with a mass ratio of 2:2:6; the lipophilic elastic deformation material is the polyacrylamide-based elastic microsphere material provided in Preparation Example 1; the asphalt material is oxidized asphalt; the lipophilic modified bridging plugging material is derived from Preparation Example 5;

[0124] The preparation method of the drilling fluid loss circulation control agent used while drilling provided in this embodiment is the same as that in Example 1.

[0125] Example 5

[0126] A drilling fluid loss circulation control agent used while drilling, the difference from Example 1 is only that the oil-absorbing and swelling solid particle material is only composed of ethylene-propylene-diene monomer rubber, and other components, dosages and preparation methods are the same as those in Example 1.

[0127] Example 6

[0128] A drilling fluid loss circulation control agent used while drilling, the difference from Example 1 is only that the oil-absorbing and swelling solid particle material is only composed of olefin oil-absorbing resin, and other components, dosages and preparation methods are the same as those in Example 1.

[0129] Comparative Example 1

[0130] A drilling fluid loss circulation control agent used while drilling, the difference from Example 1 is only that the asphalt material is not added, and other components are increased to a total of 100 parts by weight according to the existing parts by weight, and the preparation method is the same as that in Example 1.

[0131] Comparative Example 2

[0132] A drilling fluid loss circulation control agent used while drilling, the difference from Example 1 is only that the oil-absorbing and swelling solid particle material is not added, and other components are increased to a total of 100 parts by weight according to the existing parts by weight, and the preparation method is the same as that in Example 1.

[0133] Comparative Example 3

[0134] A drilling fluid loss circulation control agent used while drilling, the difference from Example 1 is only that the lipophilic elastic deformation material is not added, and other components are increased to a total of 100 parts by weight according to the existing parts by weight, and the preparation method is the same as that in Example 1.

[0135] Performance test:

[0136] (1) Oil absorption and swelling performance

[0137] Mix 240 mL of white oil, 60 mL of tap water, 9 g of emulsifier and 30 g of the composite lost circulation material for oil-based drilling fluid while drilling evenly, pour it into a graduated cylinder and let it stand for 1 h. After the composite lost circulation material for oil-based drilling fluid and the liquid phase are separated, read the initial volume. Then place it in a constant temperature oven at 120 °C and 150 °C respectively and let it stand for 10 hours. Read the volume change of the composite lost circulation material for oil-based drilling fluid in the graduated cylinder and calculate the expansion rate after 10 h.

[0138] Test the composite lost circulation material for oil-based drilling fluid provided in Examples 1-6 and Comparative Examples 1-3 according to the above test method. The test results are shown in Table 1:

[0139] Table 1

[0140]

[0141] It can be seen from the data in Table 1 that:

[0142] The composite lost circulation material for oil-based drilling fluid provided in Examples 1-6 will absorb oil and expand at 120 °C and 150 °C. Among them, the expansion rate increases with the increase of the content of the oil-absorbing and expanding solid particle material; and at the same temperature, with the increase of time, the volume of the composite lost circulation material for oil-based drilling fluid basically remains stable at 8 h, indicating that its oil absorption and expansion effect and elastic deformation effect are better;

[0143] Compared with Example 1, the composite lost circulation material for oil-based drilling fluid provided in Comparative Examples 1-3 does not add asphalt materials, does not add oil-absorbing and expanding solid particle materials, and does not add oil-loving elastic deformation materials respectively, resulting in a decrease in the expansion rate of the composite lost circulation material and a small volume deformation. In particular, the composite lost circulation material provided in Comparative Example 2 has almost no expansion effect.

[0144] (2) Compatibility:

[0145] First, prepare the basic drilling fluid: specifically, the oil-based drilling fluid in use in the Liaohe area, with an oil-water ratio of 80:20 and a density of 1.7 g / cm 3 , specifically including: 80:20 white oil + 30% calcium chloride aqueous solution + 2.5% organic bentonite + 5.5% emulsifier + 1% quicklime + 3% organic lignite + 0.5% polymer filtrate reducer + 2% asphalt + 0.5% viscosity increasing and gel strength enhancing agent + 0.5% wetting agent + barite;

[0146] Then, prepare the oil-based drilling fluid by mixing 100 parts by weight of the basic drilling fluid with 5 parts by weight of the composite lost circulation material for oil-based drilling fluid while drilling.

[0147] Finally, at 50 ± 1°C, according to the test method provided by GB / T 16783.2-2012, the performance parameters (high-temperature and high-pressure filtration loss measured under the conditions of 150°C and 3.5 MPa, and the aging condition is 200°C × 16 h) of the oil-based drilling fluids prepared in Examples 1-6, Comparative Examples 1-3, and the blank basic drilling fluid were tested. The test results are shown in Table 2;

[0148] Table 2

[0149]

[0150]

[0151] Note: Core filter disc specifications: 50-200 μm, high-temperature and high-pressure filter paper: medium-speed filter paper.

[0152] It can be seen from the data in Table 2 that:

[0153] The coiled tubing composite lost circulation material for oil-based drilling fluids provided in Examples 1-6 has good compatibility with the oil-based drilling fluid. Its lipophilic property has little influence on the rheology of the oil-based drilling fluid, remains stable at 200°C, has good plugging and leakage prevention effects during coiled tubing operation, and can be applied to leakage prevention and plugging operations under different depths and temperature conditions. It is beneficial to improve the success rate of coiled tubing plugging, and the plugging effect will not weaken due to the passage of time;

[0154] Compared with Example 1, the coiled tubing composite lost circulation material for oil-based drilling fluids provided in Comparative Examples 1-3 did not add asphalt materials, oil-absorbing and swelling solid particle materials, and lipophilic elastic deformation materials respectively, resulting in a significant increase in the filtration loss of the obtained composite lost circulation material under high temperature and high pressure, and a significant increase in TC-PPA, indicating that asphalt materials, oil-absorbing and swelling solid particle materials, and lipophilic elastic deformation materials have a significant effect on improving the plugging effect.

[0155] (3) Plugging effect

[0156] A high-temperature and high-pressure lost circulation test device was used to test the plugging effect of the coiled tubing composite lost circulation material for oil-based drilling fluids on porous media. Quartz sand with a mesh size of 20-40 was used as the evaluation sand bed to simulate the lost circulation channel;

[0157] Specific test method: First, prepare the basic drilling fluid: specifically, the oil-based drilling fluid in use in the Liaohe area, with an oil-water ratio of 80:20 and a density of 1.7 g / cm 3 , specifically including: 80:20 white oil + 30% calcium chloride aqueous solution + 2.5% organic bentonite + 5.5% emulsifier + 1% quicklime + 3% organic lignite + 0.5% polymer filtration loss reducer + 2% asphalt + 0.5% viscosity increasing and gel strength enhancing agent + 0.5% wetting agent + barite;

[0158] Then, according to the proportion, add the oil-based drilling fluid with compound lost circulation material while drilling provided in Example 1 to the above basic drilling fluid (100 parts by weight of basic drilling fluid + 10 parts by weight of the oil-based drilling fluid with compound lost circulation material while drilling provided in Example 1 is Experimental Group 1, 100 parts by weight of basic drilling fluid + 5 parts by weight of the oil-based drilling fluid with compound lost circulation material while drilling provided in Example 1 is Experimental Group 2, 100 parts by weight of basic drilling fluid + 0 parts by weight of the oil-based drilling fluid with compound lost circulation material while drilling provided in Example 1 is Blank Group 1), pour it into the fluid loss cylinder of the lost circulation device, place a movable piston on its upper part, and then tighten the cylinder cover for sealing; heat the fluid loss cylinder to 150 °C, let it stand for 12 h, use a large-displacement laminar flow pump to inject water for pressurization, control the pressurization speed, increase by 1 MPa every 10 min, increase the pressure to 5 MPa, observe and record the fluid loss amount at the outlet of the sand bed, and the results are shown in Table 3;

[0159] Table 3

[0160]

[0161] It can be seen from the data in Table 3 that:

[0162] The oil-based drilling fluid with compound lost circulation material while drilling provided in Example 1 has a good plugging effect on the lost layer of the sand bed. Compared with the linear fluid loss of the basic slurry at 1 MPa, the 5% addition amount has drip leakage at a pressure of 3 MPa, the 10% addition amount has drip leakage at 4 MPa, and full fluid loss occurs at 5 MPa, indicating that the oil-based drilling fluid with compound lost circulation material while drilling provided in Example 1 has a high pressure-bearing capacity in the fracture. The oil-absorbing and swelling solid particle material, oil-loving elastic deformation material, oil-loving modified bridging plugging material and asphalt-like material in it, through bridging, stuffing, oil-absorbing and swelling plugging, and elastic deformation to improve the compressive strength and anti-shearing ability under the action of pressure difference in the wellbore, fill the fractured formation, and have a good plugging, leakage prevention and pressure-bearing effect on pores and throats with a large size distribution range, improving the success rate of lost circulation plugging.

[0163] The applicant declares that the present invention illustrates an oil-based drilling fluid with compound lost circulation material while drilling and its preparation method and application through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of each raw material of the products of the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and public disclosure scope of the present invention.

Claims

1. A composite plugging agent for oil-based drilling fluid, characterized in that: The composite plugging agent for oil-based drilling fluid comprises the following components in parts by weight:

2. The composite plugging agent for oil-based drilling fluid according to claim 1, characterized in that: At least 80% of the composite plugging agent for oil-based drilling fluid has a particle size of 0.1 to 0.8 mm.

3. The composite plugging agent for oil-based drilling fluid according to claim 1 or 2, characterized in that: The oil-absorbing and swelling solid-phase particle material comprises oil-absorbing rubber and olefin oil-absorbing resin; Preferably, the oil-absorbing rubber comprises EPDM rubber and / or polyacrylate rubber; Preferably, the mass ratio of the oil-absorbing rubber to the olefin oil-absorbing resin is (3-5):(6-5); Preferably, at least 80% of the oil-swellable solid particulate material has a particle size of 0.2 to 0.5 mm.

4. The composite plugging agent for oil-based drilling fluid according to any one of claims 1 to 3, characterized in that: The lipophilic elastic deformation material includes polyacrylamide elastic microsphere material; Preferably, the raw materials for preparing the polyacrylamide elastic microsphere material include monomers, initiators, cross-linking agents, dispersants and reinforcing agents; Preferably, at least 80% of the oleophilic elastically deformable material has a particle size of 0.5 to 0.8 mm.

5. The composite plugging agent for oil-based drilling fluid according to any one of claims 1 to 4, characterized in that: The oleophilic modified bridging plugging material is obtained by modifying the bridging plugging material; Preferably, the lipophilic modified bridging plugging material is prepared by the following method, which comprises: placing the bridging plugging material in a fluidized bed for fluidization operation, and spraying the surface modifier uniformly on the surface of the bridging plugging material through a tangential spray device at 50-65° C. to obtain the lipophilic modified bridging plugging material; Preferably, the surface modifier comprises an alkyl alcohol amide derivative, a fatty acid derivative, dimethyl dihexadecyl ammonium chloride and a methacrylate polyethylene glycol copolymer; Preferably, the surface modifier comprises the following components in parts by weight: Preferably, the bridging plugging material comprises a sheet-like filling material, a rigid bridging material and a composite fiber material; Preferably, the bridging plugging material comprises the following components in parts by weight: 20 to 30 parts by weight of sheet filling material; 40-50 parts by weight of rigid bridging material; 30-40 parts by weight of composite fiber material; Preferably, the flaky filling material comprises any one of calcite, mica flakes or cellophane, or a combination of at least two thereof; Preferably, at least 80% of the flaky filler material has a particle size of 0.2 to 0.6 mm; Preferably, the rigid bridging material comprises any one of marble, ceramsite or limestone or a combination of at least two thereof; Preferably, at least 80% of the rigid bridging materials have a particle size of 0.1 to 0.8 mm; Preferably, the composite fiber material comprises any one of cottonseed hulls, asbestos powder or paper fibers, or a combination of at least two thereof; Preferably, at least 80% of the composite fiber material has a particle size of 0.1 to 0.5 mm; Preferably, at least 70% of the oleophilic modified bridging plugging materials have a particle size of 0.1 to 0.8 mm.

6. The composite plugging agent for oil-based drilling fluid according to any one of claims 1 to 5, characterized in that: The asphalt material includes oil-soluble oxidized asphalt and / or quaternary ammonium salt-type modified asphalt.

7. A method for preparing the composite plugging agent for oil-based drilling fluid according to any one of claims 1 to 6, characterized in that: The preparation method comprises: mixing oil-absorbing and swelling solid phase granular material, oleophilic elastic deformation material, oleophilic modified bridging plugging material and asphalt material, and performing crushing and particle size screening to obtain the composite plugging agent for oil-based drilling fluid.

8. An oil-based drilling fluid, characterized in that: The oil-based drilling fluid comprises a basic drilling fluid and a composite plugging agent for oil-based drilling fluid as claimed in any one of claims 1 to 6.

9. The oil-based drilling fluid according to claim 8, characterized in that: Based on 100 parts by weight of the basic drilling fluid, the amount of the composite plugging agent for oil-based drilling fluid is 5 to 10 parts by weight.

10. Use of the composite plugging agent for oil-based drilling fluid according to any one of claims 1 to 6 or the oil-based drilling fluid according to claim 8 or 9 in drilling.

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