摘要
Seepage-type gas hydrate accumulation in subsea shallow formations involves complicated thermohydro-solid coupling processes and matching problem between various accumulation elements.Theformation physical properties control local natural gas migration pathway and thus the final reservoircharacteristics of hydrates.In this paper,a novel mixed-flux model for gas hydrate accumulation isestablished and then used to simulate the process of methane gas migration into the shallow stratum toform a hydrate reservoir.The effects of reservoir heterogeneity and gas source conditions on the distribution of pore fluid and hydrate accumulation are examined.The simulation results show thatreservoir heterogeneity is conducive to the retention and lateral migration of CH4 in a hydrate stabilityzone.CH4 can contact more pore water to form a large hydrate reserve,but the formed hydrate is oftendispersed.Low-permeability layers enhance the trapping of CH4 and form a uniform and large hydratesaturation.Besides,gas source conditions have an important impact on the hydrate accumulation inreservoirs.Large gas flux,small pore water flux,continuous gas supply,high content of heavy components in natural gas,and numerous gas source points contribute to large amounts of hydrates generationin a certain time period.The presented work will deepen our understanding of the controls of natural gashydrate systems in subea shallow formations.
基金
This research is supported by the Fundamental Research Funds for the Central Universities(No.15CX05036A,18CX05009A)
the National Key Basic Research Program 973 project(No.2015CB251201)
It is also partially financed by the National Major S&T Project(No.2016ZX05056004-003)
the General Project of Shandong Natural Science Foundation(ZR2020ME090)
the National Natural Science Foundation of China(No.51974347)。
