Gas content of gas-bearing shale and its geological evaluation summary

Shale gas is one kind of natural gas that has been generated but remained in source rocks at the state of free or absorbed. The shale gas content is the key factor for shale gas assessment and core area evaluation. There are several factors of shale layers that affect the shale gas content, including TOC, Ro, pressure, temperature and moisture. Well site, laboratory, and mathematical techniques used to determine absorbed gas content, and well logs are used to determine free gas content. Evaluation of shale gas reservoirs need even more factors, the factors in the aspects of shale geologic factors such as thickness and depth, rock type and lithologic composition, microfacies and organic geochemistry factors; reservoir factors such as porosity, permeability, rock mechanics factors and sensitive factors; absorbed gas content, free gas content, total gas content, etc. Development of an effective system integration approach, comprehensive analysis, evaluation of shale gas resource potential and prediction of favorable areas are constantly being explored currently.