煤储层气水两相受限赋存输运规律及数值模拟研究

Coals are developed with a large quantity of micro- and nano-pores, while the occurrence mode of confined water/gas and multi-scale transport mechanisms are still not clear to date. Also, current numerical simulation techniques of coalbed methane (CBM) reservoirs are primarily based on undeformable solid-gas adsorption system and conventional seepage mechanics theory, which neglects the nonlinear and irreversible characteristics of multiphase fluids due to the complex micropore structure of coal. This project aims at the key scientific problems such as the occurrence characteristics of confined gas and water, the interaction mechanism between multiphase multi-scale flow and microporous medium, and coupling numerical simulation of coalbed methane reservoirs. Firstly, the confined water and gas occurrence theory and the multiscale coupled transport theory are innovatively developed in light of the physical and chemical kinetics of the interaction between the solid/gas/liquid three-phase coupling system, which attempts to reveal the occurrence mode of confined water and gas and the supernormal coupling mechanism among pore media deformation, interfacial interaction and confined occurrence and transport behavior of multiphase fluid in the micronano pore of coal. And then a new multiphase numerical simulation method will be established to characterize the multiple complex mechanisms of coalbed methane reservoirs, which will bring about the fundamental breakthrough of basic theories and methods of CBM development.

煤岩发育大量的微纳米级孔隙，目前对于微纳米级孔隙中滞留气水的受限赋存形态及多尺度输运规律仍不明晰，且现有的煤层气藏数值模拟方法主要基于稳定结构的固-气吸附体系及渗流力学理论，尚未充分考虑多相流体赋存输运规律受煤岩微观孔隙结构影响所呈现出的非线性、非可逆特征。本课题拟针对煤储层气水受限赋存特征、多相多尺度流动与微观孔隙介质之间相互作用机制以及耦合数值模拟等关键科学问题，从固/液/气三相耦合体系相间作用的物理化学动力学角度出发，创新发展煤岩微纳米孔隙系统内气水受限赋存理论与多尺度流动理论，深入揭示煤岩微纳米孔隙中滞留气水的受限赋存形态以及孔隙介质变形、介质界面作用与多相流体受限赋存输运之间的超常态力学耦合作用机制，形成更加适合煤储层特点的气藏多相多机理耦合流动数值模拟方法，带动我国煤层气资源高效开发新技术的形成与发展，推进我国煤层气事业的规模化发展。

针对煤储层气水受限赋存特征、多相多尺度流动与微观孔隙介质之间相互作用机制以及耦合数值模拟等关键科学问题，从固/液/气三相耦合体系相间作用的物理化学动力学角度出发，综合多种技术手段，开展了煤层气储层储集空间特性研究，创新发展了煤岩微纳米孔隙系统内气水受限赋存理论与多尺度流动理论，深入揭示了煤岩微纳米孔隙中滞留气水的受限赋存形态以及孔隙介质变形、介质界面作用与多相流体受限赋存输运之间的超常态力学耦合作用机制；在此基础上，综合微观孔隙结构表征、气水受限赋存规律、微观力学作用机制及流动规律理论成果，将煤岩介质抽象为由基质微孔隙、基质大孔隙和天然裂隙构成的连续介质系统，构建了煤储层真实地质环境下的气-水多机理宏观流动过程描述的物理模型和数学模型，进而，形成了更加适合煤储层特点的气藏多相多机理耦合流动数值模拟方法，深入探索了提高煤层气井单井产量的可行性工艺方法，为我国煤层气增产技术瓶颈突破提供有力理论支撑。