针对平桥南页岩气区块前期高压页岩气井生产套管环空带压现象,开展弹韧性水泥浆体系的优化,从而改善固井质量和提高水泥环的长效密封能力。综合分析平桥南区块前期出现环空带压原因,通过物理模拟装置开展固井水泥环密封能力评价实验,揭示环空带压原因;采用相间填充技术,实现水泥石脆性改造;并采用纳米乳液填充技术,实现空隙填充,降低水泥石孔隙度,减少微环隙;通过水泥浆体系优化,水泥石弹性模量较之前所用韧性水泥石降低10 %以上,水泥石残余应变降低30 %以上;通过现场6口井的现场应用,固井质量优良率100 %,且目前尚未发生生产套管环空带压现象。低残余应变弹韧性水泥浆体系的应用,为防止页岩气井生产套管环空带压提供了新的技术方法和手段,具有良好的借鉴意义和推广价值。

In the early stage of shale gas block in southern Pingqiao, the annular pressure phenomenon of casing production existed in high pressure shale gas wells, so that the elastic and ductile cement slurry system is optimized to improve the cementing quality and improve the long-term sealing ability of cement ring. Comprehensive analysis for the reason of this phenomenon is made, and through the physical simulation device, the sealing ability evaluation experiment of cement ring is carried out to reveal it. By interphase filling technology, the brittleness of cement is improved. Meanwhile, nano-emulsion filling technology is used to realize void filling and reduce porosity of cement and micro-ring gap. After the optimization of cement slurry system, the elastic modulus of cement slurry and the residual strain of cement slurry are reduced more than 10 % and 30 % respectively. As for as the field application of 6 wells in site, the cementing quality rate is 100 %, and the casing annulus pressure phenomenon has not happened yet. The application of low residual strain elastic ductile cement slurry system provides new technical method and means for shale gas wells to prevent annulus zone pressure, which have a good reference significance and popularization value.