Abstract:

We present a new and efficient methodology for the explicit representation of thermodynamic phase behavior associated with multicomponent two-phase flow in porous media. The method is based on interpolation in the discretized tie-line (Gamma) space. Since a large number of supporting points may be required needed for direct discretization of the Gamma-space, the discretization is performed adaptively during the simulation. A procedure based on the generalization of the octree data structure is proposed for adaptive discretization of the Gamma-space, which can be of arbitrary dimension. Then, the tie-lines space is tessellated using Delaunay triangulation and the natural-neighbor interpolation technique is used inside a simplex. It is important to note that the EoS computations need to performed only for a limited number of supporting points and that a different EoS model (or EoS-free model) can be used for different regions of the Gamma-space.

Based on this method, a new nonlinear formulation for general purpose compositional simulation for both immiscible and miscible displacements is proposed. The representation of the sub-critical space is based on the tie-line variables; whereas the super-critical space is parametrized using overall compositions as nonlinear unknowns. Variable substitution is based on the parametrized critical tie-line and the Minimal Critical Pressure criterion.

Numerical experiments indicate that the proposed approach reduces the cost of the thermodynamic related computations quite substantially compared with the standard methods.

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Copyright 2011, Rustem Zaydullin: Please note that the reports and theses are copyright to their original authors. Authors have given written permission for their work to be made available here. Readers who download reports from this site should honor the copyright of the original authors and may not copy or distribute the work further without the permission of the author, Rustem Zaydullin.