A saturated saltwater drilling fluid based on salt-responsive polyampholytes

• 作者: CUI Wuge HE Yinbo JIANG Guancheng YANG Lili YE Chenxi
• 来源期刊: 石油勘探与开发:英文版
• 学科: 工学
• 关键词: salt-responsiveness antipolyelectrolyte effect POLYAMPHOLYTE saturated saltwater DRILLING FLUID
• 年，卷（期）: 2019,（2）
• 页码范围: 401-406
• 页数: 6页
• 分类号: TE

摘要

Based on special antipolyelectrolyte effect of zwitterion polymer with same quantity of anionic and cationic charges, we developed two types of salt-responsive polyampholytes, one with high molecular weight and low charge density(HvL) and the other with low molecular weight and high charge density(LvH), by inverse emulsion polymerization. Molecular structure and salt-responsiveness of them were characterized by 1 H-NMR and rheology measurement, respectively. HvL and LvH were evaluated in saturated-salt bentonite suspension and influences of their ratio on apparent viscosity and fluid loss were investigated as well. The results indicate that HvL is better at decreasing fluid loss while LvH is better at maintaining low viscosity. A saturated saltwater drilling fluid centering on HvL and Lv H with simple formula was designed and applied. It is indicated that salt-responsive polyampholytes are fundamentally better than AM-AMPS anionic copolymer and AM-AMPS-DMDAAC amphoteric copolymer. The saturated saltwater drilling fluid has excellent thermal stability, tolerance to bentonite and shale cuttings, and certain resistance to CaCl2. Salt-responsive polyampholytes can be used in KCl-saturated drilling fluid, with universal adaptability.