China University of Petroleum

Jingdong Hu

Guancheng Jiang

Yinbo He

Lili Yang

Chong Liu

Lin Cheng

Deli Gao

Yong Wang

Haifang Sun

Zhaohui Wang

Yongqing Zhang

Qingying Ge

Xi Wang

Yong Qin

Fan Liu

Chunyao Peng

Guangchang Ma

The present invention relates to the well drilling field in petroleum industry, in particular to a drilling fluid additive composition suitable for coal-bed gas wells, and a water-based drilling fluid and use of the water-based drilling fluid. The drilling fluid additive composition suitable for coal-bed gas wells, 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); the capsulating agent is a comb-like polysaccharide compound; the filtrate reducer is nanocrystalline cellulose, and the amphiphobic wettability reversal agent is a dual-cation fluorocarbon surfactant. The composition provided in the present invention can be used as an additive in a solid-free brine drilling fluid, so that the brine drilling fluid obtains advantages of a high penetration rate and a low residue rate. 

Drilling fluid additive composition suitable for coal-bed gas wells, and water-based drilling fluid and use thereof

The present invention relates to the well drilling field in petroleum industry, in particular to a drilling fluid additive composition and a water-based drilling fluid suitable for high pressure plugging while drilling. The composition contains a bridging agent, a nano-plugging agent, a rheological modifier, a bionic wall bracing agent, and a bionic shale inhibitor, wherein, the bridging agent is a weak-crosslinked copolymer, in which the content of cross-linker structures is 0.1-1 wt. %; the nano-plugging agent is modified nanometer silicon dioxide particles; the rheological modifier is a dimer acid-organic amine copolymer; and the bionic wall bracing agent is carboxymethyl chitosan with a dopamine-derived base group grafted on its main chain. With a synergistic effect among the bridging agent, the nano-plugging agent, the rheological modifier, the bionic wall bracing agent, and the bionic shale inhibitor in the composition provided in the present invention, the water-based drilling fluid containing the composition as additive can attains an excellent plugging effect in a drilling process.

Drilling fluid additive composition and water-based drilling fluid suitable for high-pressure plugging

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Beijing, China

Jingdong Hu