天然气水合物地层渗透率研究进展

天然气水合物开采涉及传热、水合物分解相变、多相渗流和地层变形4个物理过程。多相渗流过程伴随着对流传热,影响传热效率;多相渗流过程影响孔隙压力的消散速率,引起有效应力改变而影响地层变形;多相渗流过程影响传热的效率和孔隙压力的消散速率,使温度和压力条件发生变化,影响水合物的分解。多相渗流过程中,某相流体的有效渗透率不仅与该相流体的饱和度有关,还与地层绝对渗透率有关。地层绝对渗透率是多相渗流过程的关键参数之一。概述不同贮存状态水合物、地层孔隙率、水合物饱和度和地层有效应力对地层绝对渗透率影响的研究内容。以国内外天然气水合物地层绝对渗透率研究成果为基础,将来的研究重点主要包括粉细砂、黏土类地层和各向异性地层多相渗流研究,以及地层有效应力对绝对渗透率影响研究。

Review on the Permeability of Hydrate-Bearing Sediments

Multiphase fluid flow, Conductive and convective heat transfer, intrinsic kinetics of hydrate decomposition, and deformation of sediments are four basic physical chemical processes in the exploitation of gas hydrate. The multiphase fluid flow leads to the pore pressure dissipation and the deformation of hydrate bearing sediments (HBS) accompanied by the convective and conductive heat transfer, and then the hydrate recovery. The absolute permeability of HBS is one of the key controlling factors. The advances in the absolute permeability with the qualitative and experienced relations to pore-scale distribution of hydrate, porosity, saturation of hydrate, and effective stress of HBS are summarized. The main directions and issues on the absolute permeability in the multiphase fluid flow of the HBS exploitation are presented.