US Patent No. 9,902,890


Patent No. 9,902,890
Issue Date February 27, 2018
Title Drilling Fluid Additive Composition Suitable For Coal-bed Gas Wells, And Water-based Drilling Fluid And Use Thereof
Inventorship Guancheng Jiang, Beijing (CN)
Yinbo He, Beijing (CN)
Chong Liu, Beijing (CN)
Qingying Ge, Beijing (CN)
Lili Yang, Beijing (CN)
Yong Wang, Shenyang (CN)
Yongqing Zhang, Beijing (CN)
Zhaohui Wang, Beijing (CN)
Lin Cheng, Beijing (CN)
Jingdong Hu, Beijing (CN)
Deli Gao, Beijing (CN)
Haifang Sun, Beijing (CN)
Xi Wang, Beijing (CN)
Assignee China University of Petroleum (Beijing), Beijing (CN)

Claim of US Patent No. 9,902,890

1. A coal-bed gas well drilling fluid additive composition, comprising a tackifying and shear improver, a capsulating agent,
a filtrate reducer, and an amphiphobic wettability reversal agent, wherein:
the tackifying and shear improver is a copolymer comprising structural units represented by formula (1), structural units
represented by formula (2), and structural units represented by formula (3), wherein:

wherein R1, R1?, R2, R2?, R5, R5?, R4 and each R7 are independently selected from H and C1-C8 alkyl; R3, R6 and R8 are independently selected from C0-C8 alkylene; X is selected from —NH— and —O—; n is 1-4;

the capsulating agent is a comb-like polysaccharide compound, comprising side chains and a main chain; the side chains are
provided by a compound represented by formula (I) and a compound represented by formula (II), and the main chain is provided
by a sulfonated polysaccharide compound, wherein, the sulfonated polysaccharide compound is selected from a sulfonated starch,
a sulfonated cellulose compound, and a sulfonated xanthan gum:

wherein, L1, L1?, L2 and L2? are independently selected from H and C1-C6 alkyl;

the filtrate reducer is nanocrystalline cellulose, and
the amphiphobic wettability reversal agent is a dual-cation fluorocarbon surfactant of which the cation part is represented
by formula (a):

wherein, each R1 is independently selected from C1-C6 alkyl, each R2 is independently selected from H and C1-C6 alkyl, each R3 is independently selected from C1-C10 alkylene, each n? is independently selected from 3-15, and m is 1-10.