Abstract:

Gas reservoirs in the Upper Triassic Xujiahe Formation, southwestern Sichuan Province are characterized by low resistivity, complex genetic types and complex gaswater relationships, which make them hard to identify. Using data from core analysis, logging, structures, testing and logging responses, we thoroughly examine genetic pattern of low resistivity gas reservoirs in the study area from macro and microviews. According to this study, main controlling factors responsible for the development of these low resistivity gas reservoirs are: 1) muddy sandstone reservoirs with low porosity and permeability developing in the context of lowamplitude structures; 2) complex pore configurations, high water saturation, and high formation water salinity; 3) lowenergy sedimentary environment resulting in fine particles in reservoirs, high mud content, some clay minerals with conductivity and enrichment of conductive minerals in certain areas. Reservoir quality has a negative correlation with resistivity.