关键词: 降滤失剂, 阴离子聚合物, 抗高温, 抗盐, 抗钙

Abstract: A ternary copolymer of 2-acrylamide-2-methyl propane sulfonic acid (AMPS),acrylamide (AM) and sodium styrene sulfonate (SSS) was designed and synthesized by free radical polymerization as fluid loss additive for drilling fluid at high temperature and high salt content. The chemical structure of the copolymer was characterized by Fourier transform infrared spectrum (FT-IR). When 1.8% fluid loss additive was added into the freshwater based mud,filtration of drilling fluid was 7.9 mL at room temperature and 13.5 mL at 210℃. In the presence of NaCl of concentration 25% and CaCl₂ of concentration 3% as salt water mud,the filtration values of drilling fluid were 14.8 mL and 11.0 mL,respectively. Scanning electron microscopy (SEM) analysis showed the microstructure of the surface of the filter cake obtained from the drilling fluid. When fluid loss additive was adsorbed on the surface of clay particles,clay particles were dispersed in the drilling fluid to form steady dispersion system. The filter cake would be uniform and fluid loss was reduced.

Key words: fluid loss additives, anionic polymer, temperature resistant, salt tolerance, calcium resistance