川南筇竹寺组超深层页岩气水平井油层套管固井关键技术OA

The Cambrian Qiongzhusi Formation in southern Sichuan is the most favorable shale gas exploration and development layer after the Silurian Longmaxi Formation.The target layer,Qiongzhusi Formation,is buried at a depth of 4 000-4 500 meters,with developed geological fractures,well leakage,and gas invasion coexisting,and a narrow safe density window.The cementing construction of oil reservoir casing faces technical challenges such as difficulty in safely inserting the casing,difficulty in maintaining stable pressure and preventing leakage and gas channeling in the horizontal section,and difficulty in flushing the oil-based drilling fluid,which affects the quality of cement bonding.To this end,by establishing a risk classification evaluation standard for the safe insertion of shale gas horizontal well oil casing,scientifically guiding the technical measures for well opening,strengthening the technical measures for well opening,and adopting the rotating casing process to ensure the safe insertion of oil casing,optimizing the dual setting dual density anti gas channeling toughness cement slurry system to achieve leak prevention and pressure stability,and using oil displacement type anti pollution flushing isolation fluid to improve displacement efficiency and cement bonding quality.This series of supporting technologies has been applied on-site in 5 wells,with an excellent cementing quality rate of 94.06％for oil casing,providing technical reference for similar deep shale gas horizontal wells.