CN-119431911-B - Rubber capable of expanding rapidly when meeting water for petroleum casing pipe and preparation method and application thereof

Abstract

The invention belongs to the technical field of water-swelling rubber for petroleum casings, and particularly relates to water-swelling rubber for petroleum casings, and a preparation method and application thereof. According to the rubber capable of expanding rapidly when meeting water for the petroleum casing pipe, the nitrile rubber with the middle acrylonitrile content is adopted, the salt-resistant water-absorbing resin is introduced, the water absorption capacity of the rubber in a salt water medium is improved, the coupling agent is introduced, the dispersion of the water-absorbing resin in the rubber is improved, the incremental filling of the water-absorbing resin is realized, and the water contact time of the inner layer of the rubber is shortened through a foaming structure. The rubber obtained by the method solves the problem of slow water absorption expansion of the existing rubber, so that the water-swelling rubber is effectively applied to the petroleum casing pipe.

Inventors

• SONG JIAN
• SUN XIAOLIANG
• LIU XINXIN
• GAO YE
• ZHAO YUJUN
• LI XIANYI
• ZHANG GUOTIAN
• GUO ZHAOQUAN
• CHEN CHAOWEI
• LUO XICHAO
• YU XINGSHENG
• GUO TIANMING

Assignees

• 中国石油天然气集团有限公司
• 中国石油集团工程技术研究院有限公司
• 北京石油机械有限公司

Dates

Publication Date

20260512

Application Date

20230728

Claims (4)

1. 1. The preparation method of the rubber capable of expanding rapidly when meeting water for the petroleum casing pipe is characterized by comprising the following steps of: 1) The raw materials comprise, by weight, 100 parts of nitrile rubber, 60-80 parts of a reinforcing agent, 0-5 parts of an anti-aging agent, 3-10 parts of a plasticizer, 1.2-3 parts of a cross-linking agent, 2-6 parts of a cross-linking auxiliary agent, 80-120 parts of a salt-resistant water-absorbing resin, 1-3 parts of a coupling agent and 8-30 parts of a foaming agent; 2) Mixing nitrile rubber, a reinforcing agent and a plasticizer according to the proportion, and banburying for 5.5-6 minutes at the temperature range of 80-120 ℃; 3) Adding an anti-aging agent, a salt-tolerant water-absorbing resin, a coupling agent, a foaming agent and a crosslinking agent according to the proportion, mixing, and banburying for 4-5 minutes at the temperature of 75-85 ℃; 4) Finally adding the cross-linking auxiliary agent according to the proportion, mixing, banburying for 3-4 minutes at the temperature of 70-90 ℃, and discharging to obtain the rubber for the petroleum casing pipe, which rapidly expands when meeting water; 5) Packing and rolling the rubber material which is obtained in the step 4) and rapidly expands when meeting water at a temperature below 100 ℃, adjusting the roll spacing and blanking to obtain the flaky rubber which is used for rapidly expanding when meeting water and used for the petroleum casing, wherein the thickness of the rubber material is 1.5-2 mm; the nitrile rubber is the nitrile rubber with the combined acrylonitrile content of 25-30 percent; the reinforcing agent is the mixture of the fast extrusion furnace black and the fumed silica in a weight ratio of 1:3; the anti-aging agent is a mixture of 2, 4-trimethyl-1, 2-dihydroquinoline polymer and 6-ethoxy-2, 4-trimethyl-1, 2-dihydroquinoline in the weight ratio of (0-2) to (0-3); the plasticizer is dioctyl sebacate, di (undecyl) phthalate or ethylene glycol monolaurate; the cross-linking agent is sulfur powder; The cross-linking auxiliary agent is the mixture of tetraethylthiuram disulfide and 2-mercaptobenzothiazole in the weight ratio of (0.5-1.5) to (1.5-4.5); The salt-resistant water-absorbent resin is sodium polyacrylate super-absorbent resin and acrylamide super-absorbent resin which are mixed according to the weight ratio of 3:1; the coupling agent is gamma-methacryloxypropyl trimethoxy silane; The foaming agent is azodicarbonamide.
2. 2. The method for preparing the rubber capable of expanding rapidly when meeting water for petroleum casing according to claim 1, wherein the method comprises the following steps: the nitrile rubber is selected from JSR N240S or FRN501; the fast extrusion furnace black is selected from Jiangxi black cat N550, and the vapor phase white carbon black is selected from cabo-O-SIL LM150.
3. 3. A rubber for petroleum casing pipe which is prepared by the preparation method according to any one of the claims 1 to 2 and is rapidly expanded by water is characterized in that the tensile strength is not less than 4MPa, the hardness is not less than 70Shore A, the tearing strength is not less than 20kN/m, the volume expansion rate of a 20mm multiplied by 2mm pattern is not less than 3 times after being soaked in 100 ℃ high-temperature water for 4 hours, the saturated expansion time is less than 1 day, and the weight expansion rate of a rubber cylinder with the diameter of 20cm multiplied by 30cm multiplied by 5cm thick is not less than 1 time after being soaked in 100 ℃ high-temperature saline water for 4 hours.
4. 4. A process for preparing a water-swellable rubber for petroleum casing according to claim 3, wherein said rubber is adhered to the surface of said petroleum casing as a water-absorbing rubber layer.

Description

Rubber capable of expanding rapidly when meeting water for petroleum casing pipe and preparation method and application thereof Technical Field The invention belongs to the technical field of water-swelling rubber for petroleum casings, and particularly relates to water-swelling rubber for petroleum casings, and a preparation method and application thereof. Background The water-swelling rubber (WSR) is a novel special rubber which can continuously absorb water at a certain speed and expand volume in a certain time in the presence of an aqueous medium. Therefore, the polar rubber has high elasticity and special water absorption expansion characteristic, and the mechanism is that the polar rubber is physically blended or grafted with a strong hydrophilic component or group, and after encountering water, water molecules form extremely strong affinity with hydrophilic groups through physical actions such as diffusion, capillary, surface adsorption and the like, so that the water molecules are coated in the rubber, and the volume and the mass of the polar rubber are expanded in multiple. When the stress resisting deformation and the osmotic pressure difference reach balance, the water-absorbing rubber keeps relatively stable elastic pressure-bearing buffering plugging effect. The petroleum casing is mainly used for supporting the well wall in the well drilling process and after well completion so as to ensure the normal operation of the whole well after well drilling process and well completion. Petroleum casing is a life line that maintains the operation of an oil well, and once the casing itself is damaged for some reason, it may result in a reduction in production of the entire well, or even rejection. Under different geological conditions, the underground stress state is complex, and the tensile, compressive, bending and torsional stresses comprehensively act on the pipe body, so that high requirements are put on the quality of the casing. In actual work, the sleeve is extremely easy to deform due to complex stress, and the operation quality and efficiency are directly affected. Therefore, some manufacturers propose a lot of countermeasure, including increasing the steel grade, thickness, etc. of the casing to improve the mechanical strength of the casing, but the patent disclosed by Xiang Degui, etc. (2018) has limited effect of preventing the casing from changing, adopts innovative technical ideas, keeps the inner diameter unchanged while the outer diameter of the casing changes, and can keep the shaft intact for a period of time. The sleeve is coated by the water-swelling rubber, the concrete working principle is that the water-swelling rubber is coated on the outer wall of the sleeve, after reaching a well position, the water-swelling rubber swells by absorbing water, the rubber layer thickens by times, and has high elastic deformation capacity due to certain flexibility and viscoelasticity, when the rubber is acted by various impact forces brought by stratum, the rubber is elastically deformed in a certain range to absorb and disperse part of the impact force, the rubber can also gather the impact force to a local area, and the elastic deformation is generated in the area, so that the energy is gradually released, and in addition, molecules in the rubber can relatively move due to shearing, so that the energy of part of the impact force is consumed, and the transmission of the impact force can be slowed down, so that the buffering and damping effects are realized. However, the current sleeve pipe has certain defects in preventing deformation due to the fact that the water-swellable rubber is used as a macromolecular network structure, has strong intermolecular attraction and macroscopic shows certain tensile strength, so that the water-swellable rubber is actually a water-swellable and molecular attraction resisting process in the water absorption process, and has a swelling effect, particularly the initial swelling speed is very slow, and particularly the water-swellable rubber generally has a mechanical blending type and a chemical grafting type, the swelling rate of the water-swellable rubber can be divided into the types of high swelling rate of more than 3.5 times, medium swelling rate of 2-3.5 times, low swelling rate of 0.5-2 times and the like. Meanwhile, the water absorption effect of the rubber is greatly influenced by temperature, medium and water contact area, especially in salt water, because strong bond combination of salt ions and water molecules is adopted, hydrophilic groups of macromolecular covalent bonds represent weaknesses in the water-capturing process, and the structural characteristics of a sleeve pipe product are added, so that the water contact area of the rubber is greatly reduced, the expansion of a rubber cylinder is changed into single-sided limited expansion, the water absorption rate and saturated water absorption rate of the rubber are reduced in multiple, and finally t