A plugging inhibitor for drilling fluid and its preparation method

Abstract

The present invention discloses a plugging inhibitor for drilling fluid and its preparation method, belonging to the technical field of oil and gas reservoir development. The plugging inhibitor is prepared by the following method: Take 100 parts of rigid particles, add water and disperse them, and then add 40-50 parts of silane coupling agent to carry out surface modification to obtain modified rigid particles, and the silane coupling agent contains terminal vinyl groups; Disperse 100 parts of modified rigid particles in water, add 40-50 parts of salt-resistant monomers, 40-60 parts of shale inhibition monomers and a cross-linking agent, and carry out free radical polymerization under the conditions of deoxygenation and initiator. After the polymerization is completed, the product is separated, purified and pulverized to obtain the product. The plugging inhibitor of the present invention can play the roles of plugging and shale inhibition; it also has the function of water absorption and swelling, and can be well applied to the plugging and inhibition of shale; it also has better temperature and salt resistance, and can withstand high temperatures of 180°C and sodium chloride brine of 15%.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas reservoir development, and particularly relates to a plugging inhibitor for drilling fluid and a preparation method thereof. Background Art

[0002] The development of shale gas plays a very important role in ensuring China's energy strategic security. The Sichuan-Chongqing region has good shale resources and has become the main battlefield for shale development. In recent years, plugging technologies have been continuously developed in the field of oil and gas exploitation. There are various types of plugging materials, and the material selectivity is more abundant for different plugging conditions. However, as oil and gas exploitation gradually shifts from conventional oil and gas reservoirs to unconventional gas reservoirs, the formation conditions are more complex and the exploitation difficulty increases, which puts forward higher requirements for plugging materials. Currently, the commonly used plugging agents are mainly asphalt substances and micro-nano materials, etc. An inhibitor is one of the essential main additives in water-based drilling fluid, and it plays an important role in improving the inhibition of the drilling fluid on shale formations, maintaining wellbore stability, and reducing downhole complications. With the increasing difficulty of deep well and ultra-deep well exploration, how to improve the temperature resistance, salt resistance, and compatibility with other drilling fluid additives has become a bottleneck problem in the application of inhibitors. Currently, the commonly used inhibitors are usually amine compounds, cationic compounds / polymers, polyamines, etc.

[0003] Currently, the plugging agents and inhibitors for drilling fluid generally have the following disadvantages: 1. The temperature and salt resistance of the treatment agents cannot meet the development requirements of deep wells and ultra-deep wells. 2. The micro-nano material-based plugging agents are prone to agglomeration, weakening the performance of the treatment agents. 3. The treatment agents only have a single function and fail to achieve "multiple functions in one agent", resulting in a high labor intensity at the drilling site. Summary of the Invention

[0004] To solve at least one of the above problems, the present invention proposes a plugging inhibitor for drilling fluid, which requires less data and has higher precision.

[0005] The technical solution of the present invention is as follows. A preparation method of a plugging inhibitor for drilling fluid, in parts by mass, includes the following steps:

[0006] S1. Take 100 parts of rigid particles, add water and disperse them, and then add 40 - 50 parts of a silane coupling agent to perform surface modification on them to obtain modified rigid particles. The silane coupling agent contains terminal vinyl groups;

[0007] S2. Disperse the modified rigid particles in water, add 40 - 50 parts of a salt-resistant monomer, 40 - 60 parts of a shale inhibition monomer, and a cross-linking agent, and carry out free radical polymerization under deoxygenation and initiator conditions. After the polymerization is completed, separate, purify, and pulverize the product to obtain it. Among them, the addition amount of the cross-linking agent is 5 - 10% of the total mass of the salt-resistant monomer and the shale inhibition monomer.

[0008] One embodiment of the present invention is that the rigid particles are calcium carbonate particles, barium sulfate particles and silicon dioxide particles, and their particle sizes are in the micron or nanometer range.

[0009] One embodiment of the present invention is that before the rigid particles are dispersed in water, the following modification operations are also carried out on them: by mass, 100 parts of rigid particles are taken and added to water and dispersed. Under the conditions of 40 °C and continuous stirring, 40 - 60 parts of tetraethyl orthosilicate are added dropwise, and then the pH is adjusted to 10 - 12 and reacted for 8 h. After the reaction is completed, they are separated, purified and pulverized.

[0010] One embodiment of the present invention is that the silane coupling agent is one of KH-570 and KH-151.

[0011] One embodiment of the present invention is that the salt-resistant monomer is a sulfonate monomer or a phosphate monomer. The sulfonate monomers include AMPS, sodium p-styrenesulfonate, sodium methallylsulfonate, potassium 3-sulfopropyl methacrylate, and the phosphate monomers include vinyl phosphoric acid.

[0012] One embodiment of the present invention is that the shale inhibition monomers include acrylamide, methacrylamide, and dimethyldiallylammonium chloride.

[0013] One embodiment of the present invention is that the initiator is one of a persulfate initiator and a redox initiation system; the crosslinking agent is N,N'-methylenebisacrylamide.

[0014] Another object of the present invention is to propose a plugging inhibitor for drilling fluid, which is prepared by any of the above methods.

[0015] The beneficial effects of the present invention are as follows: In the present invention, using rigid particles as the core and grafting salt-resistant monomers and shale inhibition monomers on the rigid particles can simultaneously play the roles of plugging and shale inhibition; in the case of using a crosslinking agent, the synthesized plugging inhibitor also has the function of water absorption and swelling, and can be well applied to the plugging and inhibition of shale. At the same time, the plugging inhibitor of the present invention, under its unique raw materials and ratio, also has better temperature and salt resistance, and can withstand a high temperature of 180 °C and 15% sodium chloride brine. Specific Embodiments

[0016] In order to have a clearer understanding of the technical features, objects and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but it should not be understood as a limitation on the implementable scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0017] The present invention will be further described below in conjunction with embodiments.

[0018] Embodiment 1

[0019] Add 10 g of calcium carbonate particles (particle size 2 μm) to 100 g of water, ultrasonically disperse for 30 minutes, place in a water bath at 40 °C, and dropwise add 4 g of tetraethyl orthosilicate under stirring (500 r / min). After the addition is complete, dropwise add 1 M sodium hydroxide solution to adjust the pH of the solution to 10. Stir mechanically at a constant temperature for 8 hours, filter, wash, dry, and pulverize.

[0020] Weigh 10 g of the powder material obtained in the previous step, add it to 100 g of water, ultrasonically disperse for 30 minutes, place in a water bath at 40 °C, and dropwise add 4 g of silane coupling agent KH-570 under mechanical stirring (500 r / min). Stir mechanically at a constant temperature for 8 hours, filter, wash, dry, and pulverize.

[0021] Weigh 10 g of the micron material obtained in the previous step, add it to 100 g of water, ultrasonically disperse for 30 minutes, add 4 g each of dimethyldiallylammonium chloride and sodium p-styrenesulfonate, 0.8 g of vinyl phosphoric acid, and 0.8 g of N,N'-methylenebisacrylamide. Place in a water bath at 60 °C and stir until all monomers are dissolved. Remove the oxygen dissolved in the water, add 80 mg of initiator ammonium persulfate, seal and stir at a constant temperature for 6 hours, filter, wash, dry, and pulverize to obtain a plugging inhibitor for drilling fluid.

[0022] Embodiment 2

[0023] Add 15 g of calcium carbonate powder (particle size 2 μm) to 100 g of water, ultrasonically disperse for 30 minutes, place in a water bath at 40 °C, and dropwise add 6 g of tetraethyl orthosilicate under mechanical stirring (500 r / min). After the addition is complete, dropwise add 1 M sodium hydroxide solution to adjust the pH of the solution to 12. Stir mechanically at a constant temperature for 8 hours, filter, wash, dry, and pulverize.

[0024] Weigh 15 g of the powder material obtained in the previous step, add it to 100 g of water, ultrasonically disperse for 30 minutes, place in a water bath at 40 °C, and dropwise add 6 g of silane coupling agent KH-151 under mechanical stirring (500 r / min). Stir mechanically at a constant temperature for 8 hours, filter, wash, dry, and pulverize.

[0025] Weigh 15 g of the micron material obtained in the previous step, add it to 100 g of water, ultrasonically disperse for 30 minutes, add 6 g each of methacryloyloxyethyl trimethyl ammonium chloride and sodium methallyl sulfonate, 0.6 g of vinyl phosphoric acid, and 0.6 g of N,N'-methylenebisacrylamide. Place it in a water bath at 60 °C, magnetically stir until all monomers are dissolved, bubble and ventilate for 20 minutes to remove the oxygen dissolved in the water. Add 80 mg of initiator ammonium persulfate, seal and stir at a constant temperature for 8 hours, filter, wash, dry and pulverize to obtain a plugging inhibitor for drilling fluid.

[0026] Example 3

[0027] Add 10 g of silica powder (particle size 0.5 microns) to 100 g of water, ultrasonically disperse for 30 minutes, place it in a water bath at 40 °C, and dropwise add 4 g of silane coupling agent KH-151 under mechanical stirring (500 r / min). Stir mechanically at a constant temperature for 8 hours, filter, wash, dry and pulverize.

[0028] Weigh 10 g of the material obtained in the previous step, add it to 100 g of water, ultrasonically disperse for 30 minutes, add 4 g each of methacryloyloxyethyl trimethyl ammonium chloride and potassium 3-sulfopropyl methacrylate, 0.4 g of vinyl phosphoric acid, and 0.8 g of N,N'-methylenebisacrylamide. Place it in a water bath at 60 °C, magnetically stir until all monomers are dissolved, bubble and ventilate for 20 minutes to remove the oxygen dissolved in the water. Add 80 mg of initiator potassium persulfate, seal and stir at a constant temperature for 8 hours, filter, wash, dry and pulverize to obtain a plugging inhibitor for drilling fluid.

[0029] Comparative Example 1

[0030] Add 10 g of calcium carbonate powder (particle size 2 microns) to 100 g of water, ultrasonically disperse for 30 minutes, place it in a water bath at 40 °C, and dropwise add 4 g of tetraethyl orthosilicate under mechanical stirring (500 r / min). After the addition is complete, dropwise add 1 M sodium hydroxide solution to adjust the pH of the solution to 10. Stir mechanically at a constant temperature for 8 hours, filter, wash, dry and pulverize.

[0031] Weigh 10 g of the powder material obtained in the previous step, add it to 100 g of water, ultrasonically disperse for 30 minutes, place it in a water bath at 40 °C, and dropwise add 4 g of silane coupling agent KH-570 under mechanical stirring (500 r / min). Stir mechanically at a constant temperature for 8 hours, filter, wash, dry and pulverize to obtain a plugging inhibitor for drilling fluid.

[0032] Comparative Example 2

[0033] Add 15 g of calcium carbonate powder (particle size 2 microns) to 100 g of water, ultrasonically disperse for 30 minutes, place it in a water bath at 40 °C, and dropwise add 6 g of tetraethyl orthosilicate under mechanical stirring (500 r / min). After the addition is complete, dropwise add 1 M sodium hydroxide solution to adjust the pH of the solution to 12. Stir mechanically at a constant temperature for 8 hours, filter, wash, dry, and pulverize.

[0034] Weigh 15 g of the powder material obtained in the previous step and add it to 100 g of water. Ultrasonically disperse for 30 minutes, place it in a water bath at 40 °C, and dropwise add 6 g of silane coupling agent KH-151 under mechanical stirring (500 r / min). Stir mechanically at a constant temperature and react for 8 hours, filter, wash, dry, and pulverize.

[0035] Weigh 15 g of the micron material obtained in the previous step and add it to 100 g of water. Ultrasonically disperse for 30 minutes, add 6 g of sodium methallylsulfonate, place it in a water bath at 60 °C, and stir magnetically until all monomers are dissolved. Remove the oxygen dissolved in water, add 40 mg of initiator ammonium persulfate, seal and stir at a constant temperature for 8 hours, filter, wash, dry, and pulverize to obtain a plugging inhibitor for drilling fluid.

[0036] Comparative Example 3

[0037] Add 10 g of silica powder (particle size 0.5 micron) to 100 g of water, ultrasonically disperse for 30 minutes, place it in a water bath at 40 °C, and dropwise add 4 g of silane coupling agent KH-151 under mechanical stirring (500 r / min). Stir mechanically at a constant temperature for 8 hours, filter, wash, dry, and pulverize.

[0038] Weigh 10 g of the material obtained in the previous step and add it to 100 g of water. Ultrasonically disperse for 30 minutes, add 4 g of methacryloyloxyethyl trimethyl ammonium chloride, place it in a water bath at 60 °C, and stir magnetically until all monomers are dissolved. Remove the oxygen dissolved in water, add 40 mg of initiator potassium persulfate, seal and stir at a constant temperature for 8 hours, filter, wash, dry, and pulverize to obtain a plugging inhibitor for drilling fluid.

[0039] To further illustrate the effects of the present invention, the plugging inhibitors of the above examples and comparative examples were tested below.

[0040] 1. Sand bed pressure-bearing experiment

[0041] Test the samples through an HPIT visible sand bed permeation filter loss instrument. Use 20-mesh - 40-mesh quartz sand, stabilize at a pressure of 2 MPa for 30 minutes, and observe the immersion depth of the samples. The base slurry formula is as follows: 4% prehydrated bentonite slurry + 0.5% LS-2A (filtration reducer) + 5% WNFB (filtration reducer) + 10% JD-6 (filtration reducer) + 3% KCl + 0.5% NaOH + barite, density 1.3 g / cm3 The final results are shown in Table 1. Among them, the dosage of the plugging inhibitor is 4%.

[0042] Table 1 Results of the sand bed pressure-bearing experiment

[0043]

[0044]

[0045] As can be seen from Table 1, the plugging inhibitor of this embodiment has good pressure-bearing plugging ability. Referring to Example 1 and Comparative Example 1, it can be seen that the further modified nanoparticles have good pressure-bearing plugging ability, while the nanoparticles grafted solely with silane coupling agent, although having a certain pressure-bearing plugging effect, have relatively poor effect; referring to Example 1, Comparative Example 2 and Comparative Example 3, it can be seen that the modified monomers have a great influence on its pressure-bearing plugging ability.

[0046] 2. Linear expansion rate

[0047] Core linear expansion reduction rate: The core linear expansion experiment was carried out using the normal temperature and pressure expansion volume measuring instrument NP-01 of Qingdao Haitongda Special Instrument Co., Ltd. to evaluate the inhibition performance. Weigh 20 g of the sample and place it in a beaker containing 100 mL of distilled water, stir it on a magnetic stirrer for 10 min to obtain the sample suspension. Weigh 10 g of bentonite for drilling fluid expansion test dried at 105 °C for 4 h and cooled to room temperature, put it into the liquid rock expansion instrument barrel, place it on a press and apply uniform pressure. When the pressure reaches 4 MPa, keep the pressure constant for 5 min and then take it off, install it on the liquid rock expansion instrument, inject the sample suspension into the measuring cylinder to soak the core. Measure the linear expansion volume in 8 h, and at the same time use distilled water for the blank test. The expansion volume of the distilled water blank test is not less than 11.5 mm, and calculate the core linear expansion reduction rate according to the formula. H - Core linear expansion reduction rate, %; ΔH1 - Core expansion volume in 8 h of distilled water, mm; ΔH - Core expansion volume in 8 h of the sample suspension, mm. The final test results are shown in Table 2. Among them, the dosage of the plugging inhibitor is 4%.

[0048] Table 2 Linear expansion rate test table

[0049]

[0050] As can be seen from the table, the plugging inhibitor of the embodiment of the present invention has a good anti-swelling rate.

[0051] 3. Rolling recovery rate of the red soil layer

[0052] The red layer soil is crushed and sieved, and the particles with a mesh size of 6 - 10 are collected. 40 g of the red layer soil particles are weighed and put into an aging tank. Then, a plugging inhibitor suspension is added. After rolling and aging at 160 °C for 16 h, the aging tank is taken out and cooled. The red layer soil particles are poured into a 40 - mesh sieve, rinsed several times with clean water, and then put into an oven to be thoroughly dried. After weighing, the rolling recovery rate of the cuttings is calculated. Among them, the dosage of the plugging inhibitor is 4%. The final test results are shown in Table 3.

[0053] Table 3 Rolling Recovery Rate of Red Soil Layer

[0054]

[0055] As can be seen from Table 3, the plugging inhibitor prepared in the embodiment of the present invention has good temperature and salt resistance effects.

[0056] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the embodiments of the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. Preparation method of plugging inhibitor for drilling fluid, characterized in that, comprising the following steps in parts by mass: S1. Take 100 parts of rigid particles, add water and disperse them, then add 40 - 50 parts of silane coupling agent containing terminal vinyl group to carry out surface modification to obtain modified rigid particles; S2. Disperse 100 parts of modified rigid particles in water, add 40 - 50 parts of salt - resistant monomer, 40 - 60 parts of shale - inhibition monomer, and cross - linker, and carry out free - radical polymerization under deoxygenation and initiator conditions. After polymerization, separate, purify and pulverize the product to obtain it; The salt - resistant monomer is sulfonate monomer and phosphate monomer. The sulfonate monomers include AMPS, sodium p - styrenesulfonate, sodium methallylsulfonate, potassium 3 - sulfopropyl methacrylate, and the phosphate monomer is vinyl phosphoric acid; the shale - inhibition monomer is dimethyldiallylammonium chloride.

2. The method according to claim 1, characterized in that, the rigid particles are calcium carbonate particles, barium sulfate particles and silicon dioxide particles, and their particle size is in micrometer or nanometer scale.

3. The method according to claim 1, characterized in that, before adding water and dispersing the rigid particles, the following modification operation is also carried out on them: in parts by mass, take 100 parts of rigid particles, add them to water and disperse, under the conditions of 40 °C and continuous stirring, dropwise add 40 - 60 parts of tetraethyl orthosilicate, then adjust the pH to 10 - 12 and react for 8 h. After the reaction is completed, separate, purify and pulverize them.

4. The method according to claim 1, characterized in that, the silane coupling agent is one of KH - 570 and KH - 151.

5. The method according to claim 1, characterized in that, the initiator is one of persulfate initiator and redox initiator system; the cross - linker is N, N'-methylenebisacrylamide.

6. A plugging inhibitor for drilling fluid, which is prepared by using the method according to any one of claims 1 - 5.

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