In an effort to resolving the problem of lost circulation,wellhead with pressure and channeling in transition-layers between high and low pressure in M oilfield,based on the study of characteristics of cement job and the mechanism of cementing loop failure in salt-gypsum beds,a pressure double balance concept and the related mathematical model are developed for the first time.It is required both effective annular fluids pressure balanced formation pore pressure before gel strength increasing 150 Pa and also balanced formation creeping rate before compression strength up to 3.5 MPa.PC-HDS CMT,a new high density KC1 cement slurry system which exhibits excellent salt resistance,anti-leakage and channeling control properties is developed,as well as the matched cementing technology are also being perfected.The results of the research have been applied successfully in high pressure salt-gypsum layer cement job in seven wells of M oilfield,and it will laid the successful foundation of drilling and completing campaign in the future.%针对M油田高压盐膏层固井井漏、井口带压和高低压过渡层窜流的问题,分析研究了盐膏层固井特点及水泥环失效机理,首次提出了环空有效液柱压力在水泥静胶凝强度发展到150 Pa前应压稳地层孔隙压力、抗压强度发展到3.5 MPa前应压稳地层蠕变的盐膏层固井双压稳理念,并建立了相应的压稳模型,研发了具有抗盐、防漏、防窜性能的PC-HDS CMT高密度KCl水泥浆体系,设计了配套的双压稳固井工艺.上述研究成果已在M油田7口井高压盐膏层固井作业中取得成功应用,为该油田继续安全顺利钻完井作业创造了良好条件.
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