Research status and currently existent problems of shale gas geological survey and evaluation in China

The United States shale gas large-scale commercial success promoted the exploration, development and research work of shale gas in China. After years of exploration and practice, China's complex geological conditions of shale gas are understood, geological theory and technological development of shale gas are expected to have a breakthrough, and the comprehensive geological theory can guarantee the shale gas exploration and development at the top speed. This paper has summarized the characteristics and distribution of rich organic shale, the generation mechanism and enrichment regularity of shale gas, the reservoir properties and the microstructure, the preservation conditions, the resources assessment and prospecting area selection as well as the research progress of shale gas geological theory, and analyzed the problems existent in shale gas geological theory research. The prospect of shale gas geological research work in the future is predicted, and the existent problems are pointed out as follows: The study of shale distribution and characteristics is not enough; the research on the influence of the sedimentary and structure on the distribution of fine shale needs to be strengthened; the generation mechanism of shale gas and the enrichment regularity of different rich organic shale types need to be studied in-depth, and the adsorption mechanism of shale gas needs further understanding; the relationship between the reservoir properties and the parameters of each shale is not clear, and the qualitative and quantitative analytical technology of the microstructure should be improved; the influence of the tectonic evolution on gas-bearing nature is not clear, and the preservation conditions index system for shale gas evaluation should be established; it is difficult to determine the key parameters for shale gas resource evaluation, and the prospecting area selection parameters system and standards need to be further improved.