页岩气成藏条件及我国黔南坳陷页岩气勘探前景浅析

Shale Gas Accumulation Conditions and Exploration Prospect in Southern Guizhou Depression

页岩气具有自身的成藏机理,需要特殊的地质条件,其成藏主要受控于页泥岩厚度、面积、总有机碳含量、有机质成熟度、矿物岩石成分、压力和温度等因素。将页岩气评价总结为生气能力、储集气能力和易开采性3个方面。黔南坳陷页泥岩自下而上主要集中在震旦系陡山沱组、下寒武统、中寒武统、上泥盆统和二叠系。通过地球化学分析,认为该地区具有页岩气成藏的基本条件,其中下寒武统(∈1)黑色高碳质页岩系和二叠系吴家坪组(P2w)页泥岩分布面积广泛,厚度大,有机质含量和热演化程度高,并且含有较多的硅质成分,是最为有利的勘探层位。

Shale gas has its own accumulation mechanism and requires secific geological conditions. Its formation is mainly controlled by such factors as thickness, area, total organic content (TOC), organic matter maturity, mineral composition, pressure and temperature of the mud shale. Shale gas assessment is summed up in three aspects: gas generating capacity, gas accumulating capacity and easy exploitation. Shale from bottom to up is mainly distributed in Sinian Doushantuo Formation, Lower Cambrian, Middle Cambrian, Upper Devonian and Permian in Southern Guizhou Depression. Through geochemical analysis, it is considered that this area has the basic conditions for shale gas accumulation. Mud shale features in wide distribution, big thickness, high organic matter content an high thermal evolution degree, and more silicastone in the high-carbon shale series of Lower Cambrian (∈1) and Permian Wujiaping Formation (P2w) which are most favorable for exploration.