US 11,053,424 B2
Temperature-resistant calcium-resistant water-based drilling fluid for oil and gas reservoir protection and use thereof
Yuping Yang, Beijing (CN); Jingping Liu, Qingdao (CN); Min Chang, Beijing (CN); Long Li, Beijing (CN); Jinhong Wang, Beijing (CN); Yan Zhang, Beijing (CN); and Jinsheng Sun, Beijing (CN)
Assigned to CNPC ENGINEERING TECHNOLOGY R&D COMPANY LIMITED, Beijing (CN); and CHINA UNIVERSITY OF PETROLEUM (EAST CHINA), Qingdao (CN)
Filed by CNPC Engineering Technology R&D Company Limited, Beijing (CN); and China University of Petroleum (East China), Qingdao (CN)
Filed on Nov. 20, 2018, as Appl. No. 16/196,511.
Claims priority of application No. 201811196158.5 (CN), filed on Oct. 15, 2018.
Prior Publication US 2020/0115613 A1, Apr. 16, 2020
Int. Cl. C09K 8/24 (2006.01); C01B 32/194 (2017.01); C01B 32/198 (2017.01); C08F 220/58 (2006.01); C08F 226/04 (2006.01); E21B 21/00 (2006.01); E21B 21/06 (2006.01); B82Y 30/00 (2011.01); B82Y 40/00 (2011.01)
CPC C09K 8/24 (2013.01) [C01B 32/194 (2017.08); C01B 32/198 (2017.08); C08F 220/58 (2013.01); C08F 226/04 (2013.01); E21B 21/003 (2013.01); E21B 21/062 (2013.01); B82Y 30/00 (2013.01); B82Y 40/00 (2013.01); C08F 220/585 (2020.02); C08F 2800/20 (2013.01); C08F 2810/00 (2013.01); C09K 2208/10 (2013.01)] 10 Claims
 
1. A temperature-resistant calcium-resistant water-based drilling fluid for oil and gas reservoir protection containing a filtrate reducer and a plugging agent,
wherein the filtrate reducer is a copolymer that contains structural units represented by formula (1), structural units represented by formula (2), and structural units represented by formula (3), and the mass ratio of the structural units represented by formula (1) to the structural units represented by formula (2) to the structural units represented by formula (3) is (0.1-0.2):1:(0.05-0.1), and the number-average molecular weight of the copolymer is 10,000-100,000 g/mol;

OG Complex Work Unit Chemistry
where, R1, R2, R3, R4, R5, R6, R7, R9, R10, and R11 are H, C1-C4 alkyl, or C1-C4 alkoxy respectively and independently, and R8 is selected from C1-C4 alkylene;
the plugging agent is acrylamide-diallyldimethylammonium chloride copolymer modified graphene.