Mapping Structured Grid Properties on Triangulated Meshes

Research output: ThesisMaster's Thesis

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Abstract

The purpose of this work is to identify a reliable and effective method to map porous media properties like e.g. porosity, from a structured grid to an unstructured triangulated mesh. The generation of the unstructured triangulated grid regarding this thesis strongly relies upon a wavelet-based coarsening algorithm, which leads to a non-uniform structured grid. Depending on the applied coarsening-level one can detect differences in the results of the triangulated grid, which ultimately affects the simulated flow behavior. The computation of properties on the generated triangulated grid is of importance as it provides more flexibility regarding flow simulations. The final objective of this thesis is to identify the most promising mapping algorithm to assign properties from structured on unstructured grids. In general, two major categories of mapping techniques exist, which will be discussed in more detail. Furthermore, two-phase flow simulations, using MRST library, are conducted on the considered grid structures to investigate the simulated flow behavior on different grids. The most important parameters in this study are the coarsening- level, produced volumes and the well placement. In order to determine the most reliable mapping technique, the algorithms of interest are applied on two datasets. For evaluation of the methods, three different aspects are considered that are complexity of implementation, accuracy and runtime. Produced oil, breakthrough time and water cut are selected as output parameters for the flow simulations. In addition, a set of other parameters was tested to get additional insight in the mapping algorithm, which will be discussed in the thesis. As a conclusion, the simplest algorithm, the inverse distance method, shows the best performance for this specific mapping purpose. Furthermore, the simulation results show some interesting effects; by using a triangulated grid, the oil production decreases the higher the coarsening level is picked. This can be traced back to the calculation of pressure that is biased by the mapped properties. Moreover, the simulation results indicate a faster breakthrough if using a structured uniform instead of a coarsened grid.

Details

Translated title of the contributionMappen von strukturierten Gitterparametern auf triangulierte Gitter
Original languageEnglish
QualificationDipl.-Ing.
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Award date19 Oct 2018
Publication statusPublished - 2018