抗高温耐盐型钻井液用降滤失剂的合成与性能评价

摘要

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.%选用对苯乙烯磺酸钠（SSS）、2-丙烯酰胺基-2-甲基丙磺酸（AMPS）、丙烯酰胺（AM）单体为原料，利用自由基聚合的方式，得到一种抗高温耐盐聚合物降滤失剂。通过傅里叶红外光谱分析（FT-IR）表明合成产物结构与设计结构相符。当降滤失剂加量为1.8%时，室温下和210℃下淡水基浆的滤失量分别为7.9mL和13.5mL；在25%NaCl和3%CaCl2的盐水泥浆中，钻井液的滤失量分别为14.8mL和11.0mL。通过扫描电镜（SEM）可以分析钻井液形成的滤饼的微观结构，由此得到降滤失剂作用的机理是：当降滤失剂吸附在黏土表面时，降滤失剂可以使黏土颗粒在钻井液中分散，从而形成致密的滤饼来减少滤失量。