A Comparative Study on Drag Reduction Methods for Continental Shale Drilling in the Fuxing Block, Southeastern Sichuan Basin

Extended-reach horizontal wells in continental shale formations of the Fuxing Block, southeastern Sichuan Basin, face prominent challenges, including drag and torque exceeding 50 metric tons and difficulties in weight-on-bit (WOB) transfer. Continental shale is characterized by high porosity, high permeability, distinct amphiphilic properties, and rapid performance degradation of oil-based drilling fluids (OBDF). These features lead to the formation of thick filter cakes and compacted cuttings beds, which further exacerbate abnormal drag. Existing research often focuses on single technical aspects, lacking integrated, full-cycle multi-factor coupling analysis. Based on field data from 14 drilled wells in the…