Commun. Comput. Phys., 1 (2006), pp. 827-846. Numerical Simulation of Compositional Flow in Porous Media under Gravity Zhangxin Chen 1*, Guoqiang (Joe) Zhou 2, Dan Carruthers 21 Center for Scientific Computation, Southern Methodist University, Dallas, TX 75275-0156, USA.Research Center for Science, Xi'an Jiaotong University, Xi'an 710049, P. R. China.Center for Advanced Reservoir Modeling and Simulation, College of Engineering, Peking University, P. R. China. 2 The Permedia Research Group, 577 Somerset St. W., Ottawa, Ontario K1R 5K1, Canada. Received 9 November 2005; Accepted (in revised version) 15 March 2006 Abstract This paper is concerned with the numerical simulation of multiphase, multicomponent flow in porous media. The model equations are based on compositional flow with mass interchange between phases. The compositional model consists of Darcy's law for volumetric flow velocities, mass conservation for hydrocarbon components, thermodynamic equilibrium for mass interchange between phases, and an equation of state for saturations. High-accurate finite volume methods on unstructured grids are used to discretize the model governing equations. Special emphasis is placed on studying the influence of gravitational effects on the overall displacement dynamics. In particular, free and forced convections, diffusions, and dispersions are studied in separate and combined cases, and their interplays are intensively analyzed for gravitational instabilities. Extensive numerical experiments are presented to validate the numerical study under consideration. Notice: Undefined variable: ams in /var/www/html/issue/abstract/readabs.php on line 163 Notice: Undefined variable: pac in /var/www/html/issue/abstract/readabs.php on line 164 Key words: Compositional model; reservoir simulation; finite volume method; unstructured grids; gravitational effect; free and forced convections; diffusions; dispersions; numerical experiments. Notice: Undefined variable: email in /var/www/html/issue/abstract/readabs.php on line 168 Correspondence to: Zhangxin Chen , Center for Scientific Computation, Southern Methodist University, Dallas, TX 75275-0156, USA. Email: zchen@mail.smu.edu