随着常规油气资源勘探难度的增加,煤层气、页岩气等非常规油气资源在能源结构中的地位越来越重要。认识和了解煤层和页岩孔隙中甲烷和二氧化碳的吸附特征及岩石形变规律,对于煤层气、页岩气的资源评价和开发有着十分重要的意义。本文在借鉴前人岩石孔隙表征结果的同时,采用氮气探针气体吸附法分析了4个煤岩样品和11个页岩样品的孔隙结构的特征,发现纳米尺度(<50 nm)孔隙较为丰富。鉴于纳米级孔隙所独有的纳米尺寸效应及其对气体吸附的重要作用,本研究针对这类孔隙-气体的相互作用开展了一系列计算模拟工作,淬火固体密度泛函理论(Quenched solid density functional theory, QSDFT)和DPD方法是本文采用的主要研究方法。
首先,本文采用淬火固体密度泛函理论(Quenched solid density functional theory, QSDFT)研究了地质条件下甲烷和二氧化碳在煤层中的吸附行为。研究的重点是吸附过程中温度,压力以及孔径分布对于煤岩变形的影响。研究结果包括,0.5到50nm的煤层孔在298K和360K下100MPa的压力范围内的吸附量,密度分布曲线以及溶剂化压力曲线。...
【英文摘要】
Unconventional energy (e.g. coal bed methane, shale gas) now is playing more important roles in the whole energy system. Understanding the adsorption capacity and deformation change during adsorption of methane and CO2 on coal and shale, may help the exploitation and resoure evaluation. Four coal samples and eleven shale samples were measured by N2 adsorption method. Isotherms as well as pore size distrubtions of these samples were obtained. Base on these exmperimental data, a systematic simulation work wer...