川西高密度钻井液技术难点分析及对策

Technical difficulties and countermeasures of high density drilling fluid in west Sichuan

川西地区作为中石化西南地区油气勘探开发重要地区,重点开发高庙子、中江区块,钻遇地层复杂,主要目的层为上、下沙溪庙组,地层压力系数高,自二开起,钻井液密度超过2.10g/cm^(3),高密度钻井液在施工过程中流变性控制难度大,地层井壁失稳严重,地层安全密度窗口窄,水平段摩阻大,电测、下套管困难。针对川西地区高密度钻井液施工过程中的技术难点,通过分析沙溪庙组地层井壁失稳原因,优化控制高密度钻井液流变性,降低长裸眼段摩阻,形成高密度钻井液现场技术对策。

The west Sichuan area is an important area for oil and gas exploration and development in the southwest of China Petrochemical Corporation.It focuses on the Gaomiaozi and Zhongjiang blocks.The strata encountered in the area are complex.The main target strata are the upper and lower Shaximiao formations with high formation pressure coefficient,since the second opening,the density of drilling fluid exceeds 2.10 g/cm^(3),the rheological property of high-density drilling fluid is difficult to control during construction,the wellbore in⁃stability of Shaximiao formation is serious,the formation safety density window is narrow,and the friction of horizontal section is large,and it is difficult to measure and run casing.In view of the technical difficulties in the construction of high-density drilling fluid in west Sichuan,on-site technical countermeasures were formed through laboratory experimental analysis.