Mechanism and Unblocking Method of Shale Gas Wellbore Blockage in Southeastern Sichuan Basin

In shale gas reservoirs with normal pressure and low recovery, the removal of blockages is a key process for ensuring sustainable production. Current research has predominantly focused on carbonate/sulfate scaling during water-flooding processes and corrosion-induced blockages in gas wells, but limited concern has been given to mechanistic studies and remediation methods of shale gas well blockages. In the presented work, blockage in shale gas well L1 in the Southeast Sichuan Basin was selected as the study object. First, the composition of the blockage is determined as 29.43% water, 49.59% organic (amides), and 20.98% inorganic (FeCO3, FeS, CaCO3, etc.) through component analysis methods, including thermogravimetric (TG), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS). Then, a blockage unblocking system, which is composed of 8% hydrochloric acid and 3% hydrogen peroxide, was developed, achieving a dissolution rate of 91.2% at 80 °C. This study provides a practical and innovative solution for removing composite blockages formed by amide-based organic matter and inorganic salts, improves the understanding of blockage formation mechanisms in shale gas wells, and delivers meaningful value in sustaining shale gas well productivity.