Application of Composite Brine Drilling Fluid in the Lüxiang Faulted Basin of the Yitong Basin in Jilin

The Xing 59 well in the Lushang Fault Depression of the Jilin Yitong Basin faced significant challenges during construction due to the water hydration expansion of the Yongji and Shuangyang formations, as well as the creeping characteristics of the Sheling Formation. This resulted in severe shrinkage of large sections of mudstone, causing high friction torque, difficulty in tripping, and even stuck pipe issues, which forced the well to be side-tracked and seriously affected the economic development. To ensure low-cost, safe, and efficient drilling in this block, a low-cost composite saltwater drilling fluid system was optimized through mechanism tests on formation composition, expansion rate, and roller recovery rate. This system enhanced the inhibition of the drilling fluid and effectively slowed down the shrinkage of the Sheling Formation. Additionally, technical measures such as the introduction of a reamer were implemented to overcome the challenges encountered during drilling, ensuring the safe completion of the Xing 59 well. This solution also provides a technical pathway for the low-cost, efficient development of tight oil reservoirs, with a promising potential for wide application.