In the Gaoshiti-Moxi exploration block, central Sichuan Basin, water cut has become an obstacle for gas drilling especially in the top sections of strata. How to improve the ROP of drilling a well there with a hole size of Ø311.2 mm and laterals as long as 500-2300 m is a major issue to speed up the exploration of deep gas reservoirs. To solve this problem, a technology of strengthening the study of drilling fluid inhibition performance and reducing the density of drilling fluid was put forward. First, a type of drilling fluid formulation with 5% KCl and 10% organic salt was optimized based on the KCl-polymer drilling fluid after the comprehensive performance and economy were tested and evaluated through the introduction of organic salt into the drilling fluid. This newly formulated drilling fluid has many advantages such as strong inhibitive properties, good sealing and rheological performance, and great operability. Second, it makes the site drilling fluid management easy by adjusting and controlling drilling fluid performance and maintains the concentration of inhibiting agents according to the drilling rate. Meanwhile, it is also important to get rid of the inferior solid phases in the drill-in fluid to guarantee its cleanliness and the recycle use of such low-density drilling fluids. With this drilling fluid technology, such clean and stable boreholes through the Upper Triassic Xujiahe Fm like Moxi-11, etc. were all drilled with regular and consistent borehole gauge and successful electrical measurement, which have boosted the goal realization for the ROP enhancement in the Sinian strata.
