Fracturing Fluid-Induced Damage in Tight Sandstone Reservoirs: A Case Study from the Qingshimao Gas Field

The Qingshimao Gas Field faces significant challenges in enhancing single-well productivity and overall development efficiency due to its complex geological settings and reservoir properties. This study systematically investigates fracturing fluid-induced damage and water–rock interaction mechanisms in tight sandstone reservoirs using core samples from the Qingshimao Gas Field. Analytical techniques included pore-permeability measurements, X-ray diffraction (XRD), surface and interfacial tension assessments, nuclear magnetic resonance (NMR), wettability tests, and ion chromatography. Results show that water blocking is the dominant mechanism of fracturing fluid-induced reservoir damage.The high-temperature-resistant FVS slickwater system caused more severe water sensitivity and water blocking damage than the guar gum fracturing fluid. Water sensitivity primarily reduced the effective area of micropores (<0.2 μm), whereas water blocking predominantly affected mesopores (0.2–2 μm). Furthermore, the guar gum system increased rock hydrophilicity, while the FVS system enhanced hydrophobicity. Under high-temperature and alkaline conditions, the guar gum system promoted quartz dissolution, kaolinite-to-illite transformation, and calcite precipitation. In contrast, the FVS system exhibited lower salinity increases and minimal pH variation, indicating milder geochemical reactivity.