Optimized and Fast Drilling Technology for Deep Shale Gas Horizontal Wells in Luzhou Block

The Longmaxi shale gas reservoirs in Luzhou are deeply buried and have a high temperature. During the drilling process, technical problems such as frequent lost circulation, low rate of penetration (ROP), high failure rate of steering instruments due to high temperature, and long drilling period are frequently encountered. Therefore, on the basis of analyzing the actual formation conditions and technical challenges, the research on optimization of casing program and wellbore trajectory, plugging treatment improvement for lost circulation, selection of efficient bits, surface cooling of oil-based drilling fluid and underbalanced drilling technologies were conducted. As a result, an optimized and fast drilling technology for deep shale horizontal well in Luzhou Block was developed. This technology was applied to 34 shale gas horizontal wells in Luzhou Block. Average drilling depth of the wells was 5 760 m and the average length of horizontal sections was 1 890 m. In addition, the average ROP was increased from 5.61 m/h to 7.03 m/h. The inclined and horizontal sections were completed in one trip and the drilling footage of a single trip reached 2 330 m, which created a new record. The optimized and fast drilling technology for deep shale gas horizontal wells in Luzhou Block has ensured the safe drilling of deep shale gas, improved ROP and efficiency. It can provide a technical reference for ROP improvement of deep shale gas horizontal wells in other regions.