页岩气成藏体系研究——以四川盆地及其周缘下寒武统为例

Study on the accumulation systems of shale gas:taking the lower Cambrian in Sichuan Basin and its periphery as an example

页岩气是非常规天然气藏的一种,属于"单源一位"成藏体系,在成藏特征上不同于常规油气,集烃源体、输导体和圈闭体等所有关键的成藏体系各要素于同一套页岩层.在成藏体系的划分上,页岩气藏不同于常规成藏体系的划分.综合考虑页岩层系发育时代、沉积特征、演化历史、所处现今大地构造位置、构造特征、页岩残留状况、分布特点、埋深和含气量等因素,提出了页岩气成藏体系划分的一般性原则.将四川盆地及其周缘下寒武统页岩气成藏体系划分为川南—川东南、黔北—黔中、渝东、湘鄂西、龙门山、米仓山—大巴山和川中7个成藏体系,并按战略展开区、战略突破区、战略准备区和战略远景区4个层次对成藏体系进行了评价,明确了勘探层次.

Shale gas is a kind of unconventional natural gas,its accumulation system belongs to a kind of 'single source and one position' accumulation system.Its accumulation characteristics are different from those of conventional oil and gas.In the accumulation system of the shale gas,the hydrocarbon source body,the migration path body,the trap body and other key elements to petroleum accumulation system are all in the same set of shale layer.So the division of the shale gas accumulation systems is different from that of conventional petroleum accumulation systems.The basic principles of dividing the accumulation systems of shale gas are proposed based on considering the sedimentary time,sedimentary characteristics,evolution history,present tectonic position,structural characteristics,shale residue,shale distribution,reservoir depth and gas-bearing amount of the shale layers.According to these principle,the lower Cambrian in Sichuan Basin and its periphery can be divided into 7 shale gas accumulation systems:Southern-Southeastern Sichuan,Northern-Central Guizhou,Eastern Chongqing,Western Hubei-Hunan,Longmenshan,Micangshan-Dabashan and Central Sichuan shale gas accumulation systems.The shale gas accumulation systems were evaluated,and they are classified into four areas according to exploration order:the strategic implementation area,the strategic breakthrough area,the strategic preparation area and the strategic prospect area.