A new equi-dimensional fracture model using polyhedral cells for microseismic data sets
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AbstractWe present a method for modeling flow in porous media in the presence of complex fracture networks. The approach utilizes the Mimetic Finite Difference (MFD) method. We employ a novel equi-dimensional approach for meshing fractures. By using polyhedral cells we avoid the common challenge in equi-dimensional fracture modeling of creating small cells at the intersection point. We also demonstrate how polyhedra can mesh complex fractures without introducing a large number of cells. We use polyhedra and the MFD method a second time for embedding fracture boundaries in the matrix domain using a “cut-cell” paradigm. The embedding approach has the advantage of being simple and localizes irregular cells to the area around the fractures. It also circumvents the need for conventional mesh generation, which can be challenging when applied to complex fracture geometries. We present numerical results confirming the validity of our approach for complex fracture networks and for different flow models. In our first example, we compare our method to the popular dual-porosity technique. Our second example compares our method with directly meshed fractures (single-porosity) for two-phase flow. The third example demonstrates two-phase flow for the case of intersecting ellipsoid fractures in three-dimensions, which are typical in microseismic analysis of fractures. Finally, we demonstrate our method on a two-dimensional fracture network produced from microseismic field data.
CitationAl-Hinai O, Dong R, Srinivasan S, Wheeler MF (2017) A new equi-dimensional fracture model using polyhedral cells for microseismic data sets. Journal of Petroleum Science and Engineering 154: 49–59. Available: http://dx.doi.org/10.1016/j.petrol.2017.04.004.
SponsorsThe code used to generate the results was written in Python and used the SciPy and NumPy libraries Jones et al., 2001. The Python package Shapely was used for two-dimensional polygon calculations. Visualization was done using ParaView Henderson, 2007. For cell volume and centroid computations, the code uses the algorithm defined in Mirtich, 1996. The authors would like to acknowledge help from Dr. Ivan Yotov, Dr. Mark Mear, and Dr. Xin Yang. A portion of this research was supported by the King Abdullah University of Science and Technology Academic Excellence Alliance and Saudi Aramco.