提高油基钻井液固井质量的冲洗型隔离液技术

FLUSH TYPE SPACER FLUID TECHNOLOGY USED TO IMPROVING CEMENTING QUALITY OF OBM DRILLED WELLS

油基钻井液条件下固井作业时,一方面,套管和井壁处于"油湿"环境,水泥浆无法实现与二界面良好胶结;另一方面,油基钻井液与水泥浆完全不相容性,直接接触后流变性恶化和稠化时间急剧缩短,危及施工安全。为此,利用表面活性剂协同增效机理和功能材料应用技术,研究出提高油井钻井液固井质量的冲洗型隔离液。室内研究表明,隔离液在1.5~2.3 g/cm^3密度范围内具有良好的流变和稳定性能,耐温达到120℃,洗油效率达到95%以上,能够高效驱替油基钻井液,实现界面润湿反转,与钻井液和水泥浆相容性良好。该隔离液体系在四川地区页岩气油井钻井液条件下固井中成功应用100余井次,固井质量合格率90%以上。该冲洗隔离液能够起到隔离、清洁套管和井壁的作用,提高了油井钻井液条件下的固井施工安全和固井质量。

When cementing in wells with oil-based drilling fluid. On the one hand,the casing and borehole wall is in an oilwet condition,the cement slurry cannot form a good bond with those two interfaces. On the other hand,the OBM is not compatible with the slurry,after direct contact the rheology of the slurry will be deteriorated and thickening time is shortened rapidly,endangering the operation safety. Therefore,taking advantage of the synergistic mechanism of the surfactant and functional materials,a kind of flush type spacer was developed to improve the cementing quality of wells with oil-based drilling fluid. Laboratory research shows that the spacer has good rheology and high stability when density within 1. 5 ~ 2. 3g/cm^3,its working temperature up to 120℃,oil washing efficiency above 95%,able to effectively displace the OBM,realizing wettability reversal at theinterface. And it has good compatibility with drilling fluid and cement slurry. The spacer system has been applied successfully in more than 100 wells with oil-based drilling fluids at shale gas block of Sichuan area,the qualified rate of cementing is over90%. The flush spacer fluid can isolate,clean casing wall and borehole wall,to effectively improve the cementing operation safety and cementing quality in the OBM drilled wells.