Resource potential of water-soluble gas in the Palaeogene Huizhou Sag, Pearl River Mouth Basin

Based on the formation mechanism of water-soluble gas, combined with the geological conditions of the Palaeogene Huizhou Sag, the resource potential and utilization of water-soluble gas in the Palaeogene source rock in the Huizhou Sag are analyzed quantitatively using grid calculation method. The Palaeogene Wenchang and Enping formations of the Huizhou Sag are major source rocks that generate significant quantities of gas and the sandstone reservoirs are weakly overpressured to overpressured on the whole. Calculated according to the thickness, sandstone content, porosity, water saturation, strata pressure, temperature, and mineralization of the Wenchang and Enping Formations, the resource volume of water-soluble gas is about 1 791.49×108 m3 and 2 688.5×108 m3, 1.19 and 3.46 times that of the conventional gas, respectively. If the strata pressure is relieved to normal pressure, the degasification volume is 80.84×108 m3 and 97.04×108 m3. The water-soluble gas is an unconventional resource with great potential, and can provide substantial gas source for conventional pools through degasification.