Reservoir Characteristics of Normally Pressured Shales from the Periphery of Sichuan Basin: Insights into the Pore Development Mechanism

Reservoir characteristics and the occurrence mechanism of shale gas outside Sichuan Basin are research hotspots normally pressured shales in China. Taking on Anchang syncline from periphery as an example, X-ray diffraction, organic geochemistry, rock physical experiments were carried out to analyze reservoir their main geological controls shales. The mineralogical results show that studied mainly siliceous with a high quartz content (average 57%). these is biological origin, shown by positive correlation between carbon (TOC) contents. average porosity about 2.9%, which lower than inside Basin. Organic matter pores likely primary storage space gas, relationship TOC porosity. However, scanning electron microscopy observations poorly preserved; many have been subjected compression deformation due tectonic movements. Compared Basin, effective thickness thin stratum dip large. Thus, apt escape laterally along bedding strata. After losing significant amount pressure decreases normal pressure, makes it difficult for resist compaction overlying This probably why most reservoirs pressured, while strata commonly overpressured. study provides insights understand pore development hydrocarbon