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

Drilling deep shale gas horizontal wells in Luzhou Block of Sichuan Basin is challenging due to long drilling cycles, 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 save the cost, technological research was carried out on the casing program design optimization of horizontal wells, and 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 efficiency rock breaking technologies for special lithological formations were selected. In addition, drilling fluid systems and performance parameters were recommended based on pilot tests of ground cooling equipment. Thus, key drilling technologies with high operation safety and efficiency were formed for the deep shale gas horizontal wells in Luzhou Block. The key technologies were tested in four wells in Luzhou Block, the results show that the drilling cycle was reduced by 14.5% on average and no downhole failures were reported with an average well depth of 5 601 m and a horizontal section length of 1 884 m. The research result show that the technologies can meet the requirement of safe and efficient drilling as well as having a wide application scope in Luzhou Block.