Prospects for shale gas exploration in Wuwei Basin

The Wuwei Basin, located within the jurisdictions of Wuhu, Ma'anshan, and Chaohu cities in Anhui Province, is tectonically situated in the central part of the basin group along the Lower Yangtze region between the Dabie-Sulu and Jiangnan orogenic belts. To clarify the geological conditions, resource potential, and favorable zones of multiple sets of marine shale in this area, and provide a scientific basis for exploration deployment in the Wuwei Basin and similar areas of the Lower Yangtze region, an integrated approach was adopted, including field geological surveys, drilling data analyses (core, geochemistry, physical properties, gas content testing, etc.), and reprocessing and interpretation of 2D seismic data. The study identified two sets of sedimentary strata within the basin: Mesozoic-Cenozoic fluvial-lacustrine facies and Middle-Paleozoic marine facies. Structurally, the basin exhibited a double-layered architecture, with the upper section dominated by extensional faulted depressions and normal faults, and the lower section dominated by compression and reverse faults. Three sets of shale strata were developed in the basin: the Upper Ordovician Wufeng Formation to Lower Silurian Gaojiabian Formation, the Permian Gufeng Formation, and the Permian Dalong Formation. Among them, the Gufeng and Dalong formations had the widest and most stable shale distribution and the best geological conditions, providing favorable conditions for shale gas enrichment, preservation, and fracturing stimulation. Preliminary estimates showed that in the exploration license area of the Wuwei Basin, the shale gas resources in the Gufeng Formation and Dalong Formation were about 2 350 × 108 m3 and 1 450 × 108 m3, respectively. Notably, the Longtangwan, Wannianchang, and Fudu structural belts in the central part of the basin had the highest shale gas resource abundance in both the Gufeng and Dalong Formations, reaching a cumulative 5×108 m3/km2, indicating promising shale gas exploration prospects in this area.