1.Program Mechanisms for differential gas enrichment in organic-rich shales
The marine organic-rich shales in China is characterized by ancient age, high maturity and complex evolutionary history. There are large differences in the pore development degree, fluid pressure condition and nature gas accumulation degree of marine organic-rich shales in different area. Mechanisms for differential gas enrichment in organic-rich shales is the key scientific problem of shale gas exploration. In this project, the Sichuan Basin and adjacent area were taken as the study area. In order to seize the international scientific frontier of unconventional oil and gas geology, via systematic comparation and simulated experiment, we try: 1) to reveal the process of sedimentary diagenesis of brittle orgianic-rich shales in different paleo-oceanic environment; 2) to study the evolution of pores and fractures in different organic-rich shales (e.g. siliceous, calcareous, dolomitic organic-rich shales); 3) to illustrate the multi-scale (from nano pore to micro pore, and to fracture) gas migration mechanism in complex medium; 4) and to reveal the gas-rich and gas-lean mechanism and their controlling factors under multi-stages tectonic setting. Moreover, we want to establish: 1) the formation model of brittle organic-rich shales in differential paleo-oceanic environment; 2) the evolutionary model of pore and freature in the different types of organic-rich shales and gas-rich and gas-lean model of different geological conditions. These research results would provide scientific bases and models for prediction and assessment of shale gas exploration potentials in China.
2.ProgramTypes of orgianci-rich shales and their depositional-diagenetic controlling factors
Members Detian Yan
There are large differences in the nature gas enrichment of marine organic-rich shales in China. Mechanisms for differential gas enrichment in organic-rich shales is the key scientific issue of shale gas exploration. The distribution of different types of orgianic-rich shales and their depositional-diagenetic controlling factors are the important foundation for revealing the mechanism for differential gas enrichment and predicting the "sweet spot" of shale gas. In this project, Organic-rich shales of the Lower Cambrian, Upper Ordovician-Lower Silurian and Upper Permian in the Sichuan Basin and adjacent area will be selected and the systematic research of sedimentology, mineralogy and geochemistry will be used: 1) to reveal the relationship and distribution of different organic-rich shales in sequence stratigraphy framework; 2) to study the type and formation mechanism of organic-rich shales in different paleo-climatic and paleo-oceanic environment; 3) to illustrate the alteration, reform and evolution of different lithofacies and brittle mineral in the process of sedimentation and diagenesis; 4) to study the formation and change of brittle mineral (e.g. organic silicon and dolomite) with the participation of microorganism; 5) to reveal the formation condition and the process of sedimentation and diagenesis of different types of organic-rich shales; 6) and to establish the genetic model of organic-rich shales and the predictive model of organic-rich shales distribution. This study is an important basis for predicting the distribution of different types of organic-rich shales and studying the mechanisms for differential gas enrichment in organic-rich shales.