Evaluation of the in-place adsorbed gas content of organic-rich shales using wireline logging data: a new method and its application

Adsorbed gas content is an important parameter in shale gas reservoir evaluations, and its common calculation method is based on core experiments. However, in different areas, the correlations between the adsorbed gas content and well logging data might differ. Therefore, a model developed for one specific area cannot be considered universal. Based on previous studies, we studied the relationships between temperature, TOC, organic matter maturity and adsorbed gas content and revealed qualitative equations between these parameters. Then, the equations were combined to establish a new adsorbed gas content calculation model based on depth and total organic carbon (TOC). This model can be used to estimate the adsorbed gas content using only conventional well logging data when core experimental data are rare or even unavailable. The method was applied in the southern Sichuan Basin, and the adsorbed gas content results agree well with those calculated using the Langmuir isothermal model and core experimental data. The actual data processing results show that the adsorbed gas content model is reliable.