Key Technologies for Deep Horizontal Well Drilling of Shale Gas in Luzhou of Sichuan Basin

The drilling of deep shale gas horizontal wells in Luzhou block of Sichuan Basin has been chanllenged by long drilling cycle, low rate of penetration (ROP), high drilling tool vibration, poor drillability of special lithological formations, horizontal wellbore instability, high formation temperature, and high friction torque and sticking risk etc.. To solve these problems and to ensure operation safety and increase cost-efficiency, technological research was carried out on casing program design of horizontal wells, wellbore trajectory control and optimization of horizontal sections. As a result, the optimal parameters of the radical drilling method were recommended, and shock absorption, speed-up, and high efficient rock breaking technologies for special lithological formations were preferentially adopted. In addition, drilling fluid system and performance parameters were recommended based on pilot tests of ground cooling equipment. In this way, key drilling technologies with high operation safety and efficiency were formed for the deep shale gas horizontal wells in Luzhou block. Through the application of the key technologies in four wells in Luzhou block, the experimental results show that the drilling cycle was redcued by 14.5% and no downhole failure was reported for average well depth of 5,601.00 m and the horizontal section length of 1,884.00 m. So these technologies can meet the requirement of safe and efficient drilling as well as wide application scope in Luzhou.