固井用润湿反转剂的研究与应用

Study and Application of Wettability Reversal Agents for Well Cementing

注水泥前将黏附在环空界面上的油基钻井液和油膜清除,并将井筒内油基钻井液与隔离液的混合液转变成水润湿体系,是提高固井质量的关键因素,为此笔者研发了针对油基钻井液用润湿反转剂PC-W31S和PC-W25L,其加量范围为:PC-W31S为0.5%～1.0%(占水的质量百分数)、PC-W25L为5%～10%(占水的质量百分数),并探讨了其作用机理;重点研究了该润湿反转剂对隔离液水润湿能力的影响,2者相互促进,复配使用。评价结果表明,以PC-W31S和PC-W25L为主剂的隔离液占混合液(油基钻井液与隔离液)的体积分数不大于50%,可使混合液从油连续相完全转变为水连续相;该隔离液冲洗黏有油基钻井液的转子,冲洗效率达80%以上,冲洗后的界面为水润湿;且与油基钻井液、水泥浆的流变相容性良好,对水泥浆稠化时间和抗压强度的影响均在可控范围内。该产品在LD8-1-7井成功应用,并中标东南亚某固井项目。

To improve the job quality of well cementing, the oil base mud and oil films adhered on the surface of the borehole to be cemented have to be removed and the mixture of oil base drilling fluid and spacers in the borehole should be changed to water wetting. Two wettability reversal agents, PC-W31S and PC-W25L, have been developed to perform the tusks mentioned above. PC-W31S is added at a concentration between 0.5% and 1.0%(percent mass of water) and PC-W25L between 5% and 10%. Study of the working mechanisms of the two agents has been conducted, focusing on the effects of the wettability reversal agents on the water wetting capacity of spacers used. In the study, PC-W31S and PC-W25L were compounded to make the best use of the two. Evaluation tests of the two agents showed that when the volumetric fraction of a spacer treated with PC-W31S and PC-W25L (as the main additives) in a mixture of the spacer and oil base mud is less than 50%, the mixture can be completely turned from oil wetting (oil as the continuous phase) to water wetting (water as the continuous phase). Using the spacer to flush a rotor, more than 80% of the oil base mud adhered on the surface of the rotor can be flushed away and the flushed surface becomes water wet. The spacer is rheologically compatible with oil base drilling fluids and cement slurries, and the effects of the spacer on the thickening time and compressive strength of cement slurry are controllable. The two agents have been successfully applied on the well LD8-1-7 and won a bidding in a well cementing project in southeast Asia.