Finite element modeling of convective pore-fluid flow in fluid-saturated porous rocks within upper crust: An overview

Abstract

Convective pore-fluid flow (CPFF) plays a critical role in generating mineral deposits and oil reservoirs within the deep Earth. Therefore, theoretical understanding and numerical modeling of the thermodynamic process that triggers and controls the CPFF are extremely important for the exploration of new mineral deposits and underground oil resources. From the viewpoint of science, the CPFF within the upper crust can be treated as a kind of thermodynamic instability problem of pore-fluid in fluid-saturated porous media. The key issue of dealing with this kind of problem is to assess whether a nonlinear thermodynamic system under consideration is supercritical. To overcome limitations of using theoretical analysis and experimental methods in dealing with the CPFF problems within the upper crust, finite element modeling has been broadly employed for solving this kind of problem over the past two decades. The main purpose of this paper is to overview recent developments and applications of finite element modeling associated with solving the CPFF problems in large length-scale geological systems of complicated geometries and complex material distributions. In particular, two kinds of commonly-used finite element modeling approaches, namely the steady-state and transient-state approaches, and their advantages/disadvantages are thoroughly presented and discussed.摘要孔隙流体对流在生成地下深部矿产资源和油田过程中起着关键作用。 因此, 为了探测新的地下深部矿产资源和油田, 非常有必要对驱动和控制饱水孔隙岩石中孔隙流体对流的热动力过程进行理论分析和数值模拟。 根据科学的观点, 上地壳内孔隙流体对流问题可被归结为一类发生在饱水孔隙介质中的热动力非稳定性问题。 处理这类科学问题的关键点在于如何评价所考虑的热动力系统是否处于超临界状态。 为了克服采用理论分析和实验方法在求解上地壳内孔隙流体对流问题时的局限性, 有限元模拟方法已在过去二十多年中发展成为广泛使用的一种有效方法。 本文的主要目的是对采用有限元模拟方法求解上地壳内孔隙流体对流问题的发展过程及应用进行综述。 所考虑的应用主要涉及采用有限元模拟方法求解具有复杂几何构形和介质材料分布的大尺度地质系统中孔隙流体对流问题。 尤其重要的是, 本文详细地介绍了两种常用的有限元数值模拟方法, 即稳态方法和瞬态方法, 并对它们在模拟上地壳内孔隙流体对流问题时的优缺点进行了讨论。