川东石炭系气藏主控因素与成藏模式

Main controlling factors and hydrocarbon accumulation mode of Carboniferous gas reservoirs in east Sichuan Basin

基于对开江古隆起演化、储层特征及发育主控因素、气藏保存条件的研究,分析川东石炭系气藏成藏主控因素并总结成藏模式.认为川东石炭系气藏形成主要受三大因素控制,即开江古隆起演化控制着油气的聚集,优质储层是气藏形成的基础,盖层条件是气藏形成的关键.川东石炭系气藏成藏模式可分为两个阶段,第Ⅰ阶段是古隆起形成和古气藏形成,云南运动使石炭系储层更为发育,中三叠世印支运动时期,开江古隆起继承发展并基本定型,石炭系处于两高压泥岩层之间,下伏志留系烃源岩大量生烃,形成大规模地层-构造古气藏;第Ⅱ阶段是后期燕山和喜山运动的改造,古气藏在圈闭中重新分配.

Carboniferous is one of the most important reservoirs and producing formations,Carboniferous exploration is always the key and hot point in East Sichuan Basin even the whole Sichuan Basin. Based on research of the evolution of Kaijiang paleo-uplift,the characteristics and development controlling factors of reservoir and the preservation condition of gas pools,the controlling factors and accumulation mode of the Carboniferous gas reservoirs in east Sichuan Basin are studied,and it is held that the controlling factors of the Carboniferous gas reservoirs are: the evolution of Kaijiang paleo-uplift( which determines the accumulation of the gas reservoirs),highquality reservoir( which is the basis of forming the gas reservoirs) and cap rock condition( which is the key to forming the gas reservoirs). The accumulation of the gas reservoirs is divided into two stages. The first stage is the forming period of the paleo uplift and the paleo-gas reservoirs: Yunnan movement makes Carboniferous reservoir more developed,Kaijiang paleo-uplift is developed and basically formed in Indo movement,the Carboniferous is between two high-pressure mudstone layers,and a lot of hydrocarbon generated by the underlying Silurian source rocks forms a large scale formation-structural paleo gas reservoirs. In the second stage,the paleo gas reservoirs redistribute in traps due to Yanshanian movement and Himalayan movement.