Shale gas drilling difficulties and their solutions in the lower reach of the Yangtze River （Anhui）

Abstract:

To seek breakthroughs and discoveries in shale gas resource exploration in the lower reach of the Yangtze River， China Geological Survey deployed 25 shale gas wells in Aahui province from 2015-2021. In view of malignant leakage， difficult coring， difficult drilling and well wall instability due to complex geological conditions in the exploration area， including complex geological formations， soft and hard interbedding， fault development and broken formation， a shale gas drilling technology system has been developed for the lower reaches of the Yangtze River （Anhui） through the selection of multiple types of drill bits， optimization of drilling tool combinations， drilling fluid configuration and drilling techniques， The technology system includes high-efficiency and high-quality coring technology for the fracture zone， research on soft and hard interbedding deviation correction and control BHA， optimization of bits in strong abrasive hard formations， treatment methods for malignant leakage and sticking， drilling fluid plugging technology for horizontal well sections， and wellbore stability treatment in water sensitive formations. The research may provide beneficial reference for optimal well drilling design and drilling operations for shale gas survey.