Key Drilling Completion Techniques for Shale Gas Horizontal Wells in Pengshui Block

Shale gas,a new kind of emerging resource,has drawn more and more attention recently.The successful experiences of exploration and development for shale gas in some foreign countries show that the horizontal well is the key for successful shale gas development.However,shale gas exploration and development and related key technique research in China are still at the primary stage.Engineering difficulties in shale gas well drilling face low penetration rate,long drilling cycle,high cost and possible circulation loss.Based on the drilling practice of 4 shale gas wells in Pengshui Block,an in-depth research on formation pressure,lithology,drillability,shale caving mechanism and special requirements for cementing was made and then key techniques including air drilling,rotary steering drilling,well trajectory control,leakage prevention and sealing,drilling fluid selection, cement slurry optimization,well structure optimization,drilling bit selection,wellbore cleaning,as well as their effectiveness were analyzed.Finally some recommendations on how to increase penetration rate and to lower cost were put forward.This article might be instructive for the development of shale gas with similar geologic and reservoir conditions.