含离子液体链段抗高温高钙降滤失剂

深井超深井钻进过程中时常出现高温高钙恶劣环境，为了解决由此引发的滤失量过大问题，利用具有抗高温性能的离子液体1-乙烯基-3-乙基咪唑溴盐（VeiBr）、抗钙性能的2-丙烯酰胺基-2-甲基丙磺酸（AMPS）与丙烯酰胺（AM）进行三元共聚，得到了抗高温抗高钙降滤失剂PASV。并对制备PASV的各单体加量进行了优化，最终确定在单体质量比为VeiBr:AM:AMPS=0.53:1:2时，聚合物表现出最佳降滤失行为。室内评价结果表明，PASV抗高温性能优异，初始分解温度达290℃，可满足大多数钻井需要；当钙离子浓度为40 000 mg/L时，加入2% PASV可使基浆在150℃老化前后滤失量分别降为5.2 mL与8.6 mL，显示出良好的抗高钙降滤失效果。机理分析表明，PASV通过牢固的离子键与氢键有效吸附在黏土颗粒上，并能屏蔽Ca2+对黏土的电性中和与絮凝作用，促进黏土颗粒的分散，改善滤饼质量，从而形成致密的滤饼，降低滤失量。 

A High Temperature Calcium Resistant Filter Loss Reducer Containing Ionic Liquid Segments

High temperature and calcium contamination are always encountered in deep well and ultra-deep well drilling. To address the high filtration rate problem caused by high temperature and calcium contamination, PASV, a high temperature calcium resistant filter loss reducer has been developed with bromide salt of 1-vinyl-3-ethyl imidazole (VeiBr), which is a high temperature stable ionic liquid, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), which is a calcium resistant chemical, and acrylamide (AA) in an optimized mass ratio of VeiBr:AA:AMPS=0.53:1:2, at which the reaction product (PASV) has the best filtration control capacity. In laboratory experiment, PASV showed excellent property at high temperatures; it began to decompose at 290℃, satisfying the needs of drilling at almost all temperature conditions. A drilling fluid sample containing 40,000 mg/L calcium ions had its filtration rates before and after aging at 150℃ reduced to 5.2 mL and 8.6 mL, respectively when treated with 2% PASV, indicating that PASV has excellent filtration control ability. Mechanisms of PASV as a filter loss reducer demonstrated that PSAV molecules are adsorbed on the surface of clay particles through ionic bond and hydrogen bond, thereby shielding the electric neutralization and flocculation of clay particles by Ca2+ ions. The adsorption of PASV molecules on the surface of clay particles promots the dispersion of clay particles and improves the quality of mud cakes, hence to reduce filtration rate.