Status quo and challenges of global shale gas drilling and completion

Because shale gas exploration and development just starts its first step,neither technologies nor experiences can be available at present in China.Therefore,we first introduce the status quo of and the newest advances in the global shale gas drilling and completion.Shale gas development abroad has ever experienced the stage of vertical wells,single horizontal wells,multi-lateral horizontal wells,cluster wells,and cluster horizontal wells(PAD horizontal wells).Currently the horizontal well drilling is the main mode for shale gas exploitation abroad with great regard to the cost effectiveness;normally as for such a horizontal well,its total depth of the vertical wellbore will not exceed 3000 m,and the horizontal section will go between 500-2500 m.As for the relatively new PAD horizontal drilling,it adopts one drilling platform to drill several horizontal wells to reduce cost and save time.Foam cementing is commonly used for cementing in a shale gas well,while perforation after casing set is often for well completion.Through a comprehensive analysis of the status quo and challenges of shale gas drilling and completion abroad,we suggest that domestic shale gas drilling should focus on such issues as how to maintain wellbore stability,avoid accidents,reduce drilling cost,develop proper equipment,and choose optimal drilling fluid formulation.