Eastern Sichuan region

the relatively active belt between the stable massifs in Sichuan basin

harbors ten rows of high and steep structural zones where a great breakthrough has been made in the exploration of Carboniferous gas pools since the 1990s.The Liangshang Formation mudstone is the direct cap rock of the Carboniferous gas pools.Judging from the permeability and median pore throat radius

its sealing ability is poor

while in terms of porosity and breakthrough pressure

its sealing ability is relatively good.This single sealing ability

however

is insufficient to hold the abundant Carboniferous gas pools with high gas saturation in the study area according to the mechanism of pressure sealing

the premise for an overlying layer to seal gas accumulation in an underlying layer is the original pressure and pressure coefficient of the former is higher than that of the later.The overlying Permian Yangxin Series with abnormal high porefluid pressure serve as a high quality seal for the underlying Carboniferous gas pools.The reverse faults that extend to the surface in some high and steep structural zones can cause pressure release and hydrocarbon emission.The research results and exploration data show that the pressure coefficient of 1.30 for Permian Yangxin Series can be used as the critical value of pressure seal.When the pressure coefficient surpasses the value

the Carboniferous gas pools would be safely sealed.