【摘要】 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、CO₂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.更多还原

【Abstract】 Shale gas is one important kind of natural resources,which occurs in reservoir by free state and absorbing state.In order to reveal its accumulation mechanism,it is significant to study and illuminate the TOC content,main controlling factors,evolution rule of shale gas.In this study,we analyze the main controlling factor of free gas and absorbed gas in reservoir comprehensively by high temperature and high pressure adsorption isothermal experiment,FE-SEM,CO₂ adsorption experiment,N2 adsorption experiment and mercury injection experiment.The results show that free gas is controlled by pore types and pore structure of shale,temperature and pressure in reservoir;while absorbed gas is controlled by TOC,maturity and moisture.In different stages of hydrocarbon generation,the content of free gas and absorbed gas changes regularly.Free gas occurs in the highly mature stage,and increases the process of hydrocarbon generation and the evolution of pores.It transforms into absorbed gas in the lifting stage because of the changes of temperature and pressure,which results in free gas decrease and absorbed gas increase.更多还原