Development characteristics of organic-rich shale and strategic selection of shale gas exploration area in China

Abstract

Shale gas,as a new type of unconventional natural gas resources,its exploration and development have got great success in the U.S.A.,and fast progress in Canada,Australia and other countries.Shale gas exploration in China has just started and its study is still focused on shale gas reservoir conditions and favorable area evaluation.China's preferred shale gas favorable area is mainly related with organic-rich clay and shale,and the major optimization is a prospective area for shale gas.Complicated geological background and multi-stage evolution lead to many types of China's petroleum basins whose structures are complex.Different evolution history of each basin directly controls the development and distribution of organic-rich shale.By the different formation environment,organic-rich shale can be divided into marine thick layer organic-rich shale,continent-sea intercrossing organic-rich shale,coal-bearing strata organic-rich shale,and lacustrine organic-rich shale.Among them,the thick layer marine organic-rich shale is of first priority in China's near future shale gas exploration;continent-sea intercrossing organic-rich shale and coal-bearing strata organic-rich shale are thin in single-layer,but they have symbiotic conditions with tight sandstone gas and coal-bed gas,so the multi-layer co-mining technology of shale gas,tight sandstone gas and many other types of natural gas resources has great practical significance;the lacustrine organic-rich shale's diagenesis degree is generally low,and needs further optimization of a horizon with high-strength rock and the conditions of open hole completion for exploration and development.