New parameters for charactering the gas-bearing properties of shale gas

The hydrocarbons contained in shale pores are mainly free gas and adsorbed gas. Accurately evaluating the reservoir free phase density/hydrogen index and adsorbed phase density/hydrogen index can reflect the reservoir properties and assist in evaluating the reservoir parameters. We propose a method for calculating the free phase density/hydrogen index and adsorbed phase density/hydrogen index by using logging curves and choose the rock density and total organic carbon (TOC) content to evaluate the above parameters with high precision. Finally, we propose qualitative and quantitative application methods for the above parameters. Based on the parameters calculated by the free phase density/hydrogen index and adsorbed phase density/hydrogen index, when the free phase porosity and saturation are high, the adsorbed phase porosity and saturation are low, and the adsorbed phase-free phase volume ratio is low, the reservoir has the highest quality. The results show that the free phase density/hydrogen index and adsorbed phase density/hydrogen index can be accurately determined and evaluated, and the applications of this method are very meaningful. This study combines the advantages of predicting the physical characteristics of free gas and adsorbed gas and the gas-bearing properties of shale gas reservoirs.