含水页岩气在页岩有机质纳米孔中吸附与流动的分子动力学模拟

Shale gas is a kind of new clean energy. The successful commercialization of shale gas in the United States has stimulated the booming of shale gas development around the world, made the occurrence and transport mechanism of shale gas in micro pores become a scientific hotspot. However, the problem has not been completely solved. Researchers mainly chose pure alkanes or carbon dioxide-alkanes mixed system as the object, while as an important component of shale gas, and also a component of fracturing fluid, research on water-methane mixture system is rare. This project aims to study the water-bearing shale gas adsorption and transport in shale organic nanopores by molecular dynamics simulation. After analyzing the distribution, diffusion and transport of water and methane, by self-complied program, it is expected to identify the state of water in water-bearing shale gas under the temperature and pressure condition of shale gas reservoirs, and to reveal mechanisms of water impact on shale gas adsorption and transport in organic nanopores under different ratio of water to shale gas. The successful implementation of this project will help to display the details of microcosmic adsorption and transport phenomenon at a molecular level, clarify the essence of microscopic occurrence and transport, enrich and improve the mechanism of occurrence and transport of shale gas in microscopic state, provide theoretical support for shale gas exploitation.

页岩气是一种清洁的新能源，美国页岩气成功商业化激发世界各国对页岩气的开发热潮，同时使得页岩气的微观赋存与流动机理成为科学研究热点，然而，这个问题仍没被完全解决。研究者多选择纯烷烃或二氧化碳-烷烃混合体系作为研究对象，而同样作为页岩气重要组成成分的水，其亦为压裂液的组成成分，水-甲烷混合体系的研究却鲜见。本项目旨在通过分子动力学模拟方法，研究含水页岩气在页岩有机质纳米孔中吸附与流动，通过自编程序分析水、甲烷的分布特征、扩散特征、流动特征等，明确页岩气赋存温压条件下含水页岩气中水的赋存状态，揭示水占页岩气比例变化对页岩气在有机质纳米孔中吸附与流动的影响机理。本项目的成功实施，将有助于从分子水平展示纳米吸附与流动细节，阐明微观赋存与输运物理本质，丰富和完善页岩气微观赋存与流动机理，从而为页岩气的开采提供理论支撑。

页岩气是一种清洁的新能源，美国页岩气成功商业化激发世界各国对页岩气的开发热潮，同时使得页岩气的微观赋存与流动机理成为科学研究热点，然而，这个问题仍没被完全解决。研究者多选择纯烷烃或二氧化碳-烷烃混合体系作为研究对象，而同样作为页岩气重要组成成分的水，其亦为压裂液的组成成分，水-甲烷混合体系的研究却鲜见。本项目旨在通过分子动力学模拟方法，研究含水页岩气在页岩有机质纳米孔中吸附状态与流动特征。完成了纯甲烷体系在石墨狭缝中的吸附与流动模拟，发现甲烷密度随温度的升高而降低、随压力的升高而升高、随孔径的增加而增加；甲烷的流动速度随温度的升高而升高、随压力的升高而降低、随孔径的增加而升高。实现了含水甲烷体系在石墨狭缝中的吸附状态与流动特征模拟，发现甲烷密度随温度升高而降低、随压力的升高而升高，对孔径变化不敏感；温度、压力与孔径升高均可导致甲烷流动速度加快。随着水含量的增加，甲烷与水的流动速度迅速降低，甚至形成水锁封闭狭缝，阻止狭缝中甲烷和水的流动。以上研究从分子水平展示纳米吸附与流动细节，有助于阐明微观赋存与输运物理本质，丰富和完善页岩气微观赋存与流动机理，从而为页岩气的开采提供理论支撑。