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

Abstract The hydrocarbons contained in the shale pores are mainly free gas and adsorbed gas. Accurate evaluation of the reservoir free gas density/hydrogen index and adsorbed gas density/hydrogen index can reflect the reservoir properties and assist in parameter evaluation. We proposed a method for calculate free gas density/hydrogen index and adsorbed gas density/hydrogen index by measures, and choose the rock density and 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 free gas density/hydrogen index and adsorbed gas density/hydrogen index, when the free gas porosity and saturation is high, the adsorbed gas porosity and saturation is low, adsorbed gas-free gas volume ratio is low, the reservoir has the highest quality. The results show that free gas density/hydrogen index and adsorbed gas density/hydrogen index can be accurately determined and evaluated, and the application is also very meaningful. This study bridges the advantages in predicting the physical characteristics of the free gas / adsorbed gas and gas-bearing properties in shale gas reservoirs.