胶乳纳米液硅高温防气窜水泥浆体系

Cement Slurry Treated with Latex Nano Liquid Silica Anti-gas-migration Agent

针对顺南区块超深高温高压气井固井面临井底温度高、气层活跃难压稳的问题,研究了胶乳纳米液硅高温防气窜水泥体系。通过将纳米液硅防气窜剂与胶乳防气窜剂复配使用,协同增强水泥浆防气窜性能;不同粒径硅粉复配与加量优化,增强水泥石高温稳定性;无机纤维桥联阻裂堵漏,抑制裂缝延展,提高水泥浆防漏性能和水泥石抗冲击性能。该水泥浆体系具有流动性好、API失水量小于50 m L、直角稠化、SPN值小于1,水泥石具有高温强度稳定性好、胶结强度高、抗冲击能力强的特点。密度为1.92 g/cm^3的水泥浆体系在190℃、21 MPa养护30 h后超声波强度逐渐平稳,一界面胶结强度达12.6 MPa;水泥石弹性模量较常规低失水水泥石降低52%,抗冲击强度增加了188%,且受霍普金森杆冲击后仅纵向出现几条未贯穿的裂纹。该高温防气窜水泥浆体系在顺南5-2井和顺南6井成功应用,较好地解决了顺南区块超深气井固井难题。

Cement slurry treated with latex nano liquid silica anti-gas-migration agent has been studied for the possibility of using it in Shunnan area, where ultra-deep wells have penetrated high temperature high pressure formations. The nano liquid silica anti-gas- migration agent and latex anti-gas-migration agent are both used to synergistically enhance the anti-gas-migration performance of the cement slurry. By optimizing the particle sizes and concentrations of the silica powder, the high temperature stability of the set cement can be improved. Inorganic fibers are added into the cement slurry to stop the development of fractures, thus controlling the losses of cement slurry and improving the shock resistance of the set cement. This cement slurry has good mobility, API filter loss less than 50 mL, right-angle thickening curve, and SPN less than 1. The set cement has good high temperature stability, high bond strength, and high shock resistance. Cement slurry with density of 1.92 g/cm3, after aging at 190 ℃ and 21 MPa for 30 h, has strength （measured with ultrasonic wave method） gradually stabilized, and interface （between casing string and cement sheath） bond strength of 12.6 MPa. Compared with conventional cement slurry, the elastic modulus of the set cement has been reduced by 52%, and the shock resistance increased by 188%. Striking the set cement with Hopkinson bar has only left several pieces of fractures that do not penetrate the set cement. This cement slurry has been successfully used in the cementing of the well Shunnan5-2 and well Shunnan6, overcoming the difficulties encountered in ultra-deep gas well cementing.