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页岩气是重要的非常规天然气资源,主要以游离气与吸附气状态赋存于页岩中,研究和阐明其含量、主控因素和演化规律对于揭示页岩气成藏机理具有重要意义.采用不同条件下页岩高温高压等温吸附实验、FE-SEM、CO_2吸附、N2吸附、压汞等实验方法综合研究页岩气藏中的游离气与吸附气的主控因素.结果表明,游离气主要受页岩孔隙类型、孔隙结构、储层温度与压力等条件控制;TOC、成熟度和水分影响吸附气含量.基于吸附气体积校正、地质模型和数值计算综合表征,五峰-龙马溪组页岩中以游离气为主,其平均含量约为55%,吸附气含量约为45%.在抬升阶段,储层温度和压力发生改变,页岩气赋存形式随之变化,游离气减少,吸附气增加.
Shale gas is an important unconventional natural gas resource, which mainly occurs in shale in the state of free gas and adsorbed gas. It is of great significance to study and clarify the content, main controlling factors and evolution rules of shale gas to reveal shale gas accumulation mechanism. The main controlling factors of free gas and adsorbed gas in shale gas reservoirs are comprehensively studied by means of isothermal adsorption experiments of shale under high temperature and pressure, FE-SEM, CO 2 adsorption, N2 adsorption and mercury intrusion under different conditions. The results show that the free gas It is mainly controlled by shale pore type, pore structure, reservoir temperature and pressure, etc. TOC, maturity and moisture affect the content of adsorbed gas.According to the correction of volume of adsorbed gas, the comprehensive characterization of geological model and numerical calculation, In the rock, free gas is the main component, with an average content of about 55% and an adsorbed gas content of about 45%. During the uplift stage, the reservoir temperature and pressure change, the shale gas occurrence changes and the free gas decreases, Adsorption gas increases.