Print Email Facebook Twitter Multiscale Reconstruction of Compositional Transport Title Multiscale Reconstruction of Compositional Transport Author Ganapathy, Chandru (TU Delft Civil Engineering and Geosciences; TU Delft Geoscience and Engineering) Contributor Voskov, Denis (mentor) Degree granting institution Delft University of Technology Programme Petroleum Engineering and Geo-sciences Date 2017-08-28 Abstract Designing strategies for efficient oil production from reservoirs rely heavily on reservoir simulation studies, which in-turn is based on various nonlinear formulations. It is therefore very important to develop a robust simulation model that captures the flow of various components present in different phases and the associated thermodynamic and chemical interactions. A compositional formulation is a reliable option for understanding these complex subsurface processes. However, this type of model has a great computational cost, since the number of equations (nc) that needs to be solved in each grid block increases proportionally with the number of components employed.The solution of the multicomponent multiphase flow problem is obtained by solving the associated nonlinear governing equation describing the conservation of mass, thereby determining the pressure (P) and compositional changes (Z) of the system. On the other hand, an Equation of state (EoS) model is employed to describe the phase behavior of the system, which in turn is accomplished in two stages: Phase stability test - to identify the existence of number of phase in a particular grid cell, and Flash calculation - to determine the split fraction of components amongst the phases present. The aforesaid procedure is referred as the standard EoS based approach to solve compositional problem and they are generally arduous.In previous works, a compositional-space parameterization approach was proposed to speed up the phase-behavior calculations by replacing the flash calculation with interpolations in the parameter space of the problem. The phase behavior of gas-injection processes is predominantly controlled by the properties of the two key tie-lines that extend through the initial and the injection compositions, and hence it is convenient to parameterize the problem based on these two tie-lines. It has also been proven that the projection of composition solution onto the full tie-line space is invariant to the hydrodynamic property of the compositional system.Here we utilize this technique to develop a multiscale reconstruction of compositional transport. Two types of prolongation operators are defined based on the local saturation history, with each having different computational complexities. In the first stage, a fine scale prolongation operator is implemented on a modified conservation equation with the objective of reconstructing the leading and trailing shock positions in space. Once the position of shocks are identified, the solution lying in the regions outside the shock can be solved on a coarse-scale mesh, since the structure of the transport solution outside of the two-phase region is relatively simple. Later, the fine scale projection of this coarse solution is carried out using the constant prolongation operator. The solution for nc components lying in between leading and trailing shocks is reconstructed by solving just two equations. The proposed reconstruction strategy results in coarsening of the compositional problem, both in space and representation. By this way, the simulation time is appreciably reduced by several folds without significant loss in accuracy of the results. Also, the proposed multiscale technique is evaluated by comparing them with a suitable upscaling methodology, since they are generally characterized by an affable framework of implementation and one of the most widely sought out ways to enhance computational efficiency. Subject reservoir simulationcompositionNonlinear EquationsNumerical Mathematics To reference this document use: http://resolver.tudelft.nl/uuid:24de2b60-9c17-4f28-a086-91ee9178ebe7 Part of collection Student theses Document type master thesis Rights © 2017 Chandru Ganapathy Files PDF MSc_Thesis_Report_2017_Ch ... apathy.pdf 5.68 MB Close viewer /islandora/object/uuid:24de2b60-9c17-4f28-a086-91ee9178ebe7/datastream/OBJ/view