US 11,970,655 B2
High temperature and high salinity-resistant complementarily rigid-flexible plugging agent and method for preparing the same and water-based drilling fluid and use thereof
Jingping Liu, Qingdao (CN); Jinsheng Sun, Qingdao (CN); Kaihe Lv, Qingdao (CN); Meichun Li, Qingdao (CN); Jintang Wang, Qingdao (CN); Jiafeng Jin, Qingdao (CN); Yingrui Bai, Qingdao (CN); Xianbin Huang, Qingdao (CN); Jian Li, Qingdao (CN); and Shenglong Shi, Qingdao (CN)
Assigned to CHINA UNIVERSITY OF PETROLEUM (EAST CHINA), Shandong (CN)
Filed by China University of Petroleum (East China), Qingdao (CN)
Filed on Oct. 14, 2022, as Appl. No. 17/966,516.
Claims priority of application No. 202210790278.8 (CN), filed on Jul. 5, 2022.
Prior Publication US 2024/0010904 A1, Jan. 11, 2024
Int. Cl. C09K 8/24 (2006.01); C09K 8/42 (2006.01); E21B 21/00 (2006.01)
CPC C09K 8/24 (2013.01) [C09K 8/426 (2013.01); E21B 21/003 (2013.01); C09K 2208/10 (2013.01)] 9 Claims
 
1. A high temperature and high salinity-resistant complementarily rigid-flexible plugging agent, wherein the plugging agent is a dispersion emulsion comprising composite microspheres, wherein the composite microspheres comprise a rigid material and a flexible material coated on the surface of the rigid material;
wherein the composite microspheres have a diameter within a range of 20-60 nm or 30-70 nm;
wherein the plugging agent has a maximum temperature resistance of 240° C. and a maximum salinity resistance of 35% NaCl by percent weight;
wherein the rigid material comprises modified nano-silica, and the flexible material comprises a polymer derived from copolymerization of water-soluble temperature-resistant monomer, oil-soluble temperature-resistant monomer and divinyl benzene co-monomer;
wherein the water-soluble temperature-resistant monomer is one or more selected from the group consisting of methylacrylic acid, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, sodium vinyl sulfonate, sodium styrene sulfonate, N-vinylpyrrolidone, acrylonitrile, and N,N-dimethylacrylamide;
wherein the oil-soluble temperature-resistant monomer is one or more selected from the group consisting of styrene, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, isooctyl methacrylate, isooctyl acrylate, glycidyl methacrylate, octadecyl methacrylate and lauryl methacrylate; and
wherein the modified nano-silica is one or more selected from the group consisting of γ-methylacryloxytrimethoxysilane-modified nano-silica, vinyltriethoxysilane-modified nano-silica and bis[γ-(triethoxysilyl)propyl]tetrasulfide-modified nano-silica;
wherein a method of preparing the plugging agent includes:
(1) contacting the water-soluble temperature-resistant monomer with an emulsifier and dispersing the water-soluble temperature-resistant monomer and the emulsifier to obtain a dispersion liquid;
(2) contacting the dispersion liquid with a modified nano-silica and subjecting the dispersion liquid and the modified nano-silica to an ultrasonic treatment to obtain a first solution;
(3) mixing the oil-soluble temperature-resistant monomer and divinyl benzene, and washing and treating the mixture with lye to obtain a second solution;
(4) dropwise adding the second solution into the first solution in the presence of a RAFT chain transfer agent, so as to carry out a first reaction; wherein the RAFT chain transfer agent is benzyl N,N′-diethyldithiocarbamate; and subsequently performing a second reaction in the presence of an initiator to prepare a complementarily rigid-flexible plugging agent;
wherein the water-soluble temperature-resistant monomer is used in an amount of 3-15 parts by weight, the emulsifier is used in an amount of 0.1-1 parts by weight, the modified nano-silica is used in an amount of 1-5 parts by weight, the oil-soluble temperature-resistant monomer is used in an amount of 5-30 parts by weight, the divinyl benzene is used in an amount of 1-8 parts by weight, the RAFT chain transfer agent is used in an amount of 0.01-0.05 parts by weight, and the initiator is used in an amount of 0.01-0.2 parts by weight, relative to 100-130 parts by weight of water.