古沉积环境对烃源岩发育的影响——以川东南地区龙马溪组为例

The effect of ancient sedimentary environment on source rocks:an example of the Longmaxi Formation in southeast Sichuan

川南地区下志留统龙马溪组泥页岩分布广,厚度大,是一套优质的烃源岩,是目前我国华南地区页岩气勘探和开发的主要层位之一。古沉积环境对于高有机质丰度烃源岩的发育具有至关重要的作用。在对川东南地区龙马溪组野外露头剖面和钻井资料分析的基础上,结合前人研究成果,认为川东南地区龙马溪组主要以泥质深水陆棚、泥质浅水陆棚等沉积环境为主,认为水底缺氧的滞留环境和缓慢的沉积速率是控制龙马溪组优质烃源岩发育的主要因素。

Shales with a great thicknessin the Longmaxi Formation of the Lower Silurian are widely distributed in southeast Sichuan.The Longmaxi Formation is one of the most important strata of the shale gas exploration and development of south China.The ancient sedimentary environment plays a crucial role in the development of the high quality source rocks.Based on the data of field outcrops andwellsand previous research results of the Longmaxi formation,deep muddy shelf and shallow muddy shelf are the main sedimentary environment.The anoxic retention environment and the low sedimentary rate in early transgression stage are the main controlling factors of the high quality source rocks developed in the Longmaxi Formation.