Analysis of fracturing flowback fluids from 14 shale gas wells across 7 platforms in the Zheng'an block, Guizhou, reveals that the fluids are characterized by high salinity, elevated Na\(^+\) and Cl\(^-\) concentrations, and high levels of chemical oxygen demand (COD) and ammonia nitrogen. Na\(^+\) concentrations range from 7370 to 27396~mg/L (mean 18689~mg/L), Cl\(^-\) from 9000 to 43000~mg/L (mean 29438~mg/L), and total salinity from 17074 to 70950~mg/L (mean 48744~mg/L). The dominant microbial populations comprise iron bacteria (FEB), saprophytic bacteria (TGB), and sulfate-reducing bacteria (SRB). These characteristics indicate that the flowback fluid cannot be discharged directly withou... More >

Shale gas horizontal wells in the Hongxing Block are challenged by long horizontal sections, narrow annular clearances, well-developed fractures, and the coexistence of lost circulation and wellbore collapse. Complexities such as pipe sticking, pump surging, annular blockage, and cuttings accumulation frequently occur during reaming, severely affecting operational safety and efficiency. To overcome the drawbacks of conventional empirical methods, this paper establishes four quantitative models: displacement-pressure coupling, bottomhole Equivalent Circulating Density (ECD) constraint, critical cuttings transport displacement, and drill string safety loading. An integrated reaming technology... More >

This study investigates the key factors controlling marine shale gas preservation in Devonian–Carboniferous strata, focusing on four representative synclines in the Nanpanjiang Basin and the northern margin of the Guizhong Depression: Langdai, Xinzhai, West Yizhou, and North Yizhou. Through tectonic characterization and balanced cross-section restoration, we clarify the effects of structural style, tectonic deformation intensity, and fault properties on shale gas preservation. Wide-gentle bidirectional thrust synclines (Xinzhai and West Yizhou) offer the most favorable preservation conditions, followed by the wide-gentle unidirectional thrust syncline (Langdai); the wide-gentle nappe-type... More >