Full text loading...
-
Multiscale Multiple Point Simulation Based on Texture Synthesis
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, ECMOR XIV - 14th European Conference on the Mathematics of Oil Recovery, Sep 2014, Volume 2014, p.1 - 12
Abstract
Reservoirs result from complex and intricate natural formation processes, and are therefore very heterogeneous at multiple scales. As fluid displacements are very sensitive to heterogeneity, it is crucial to understand and characterize how petrophysical properties vary in space to be able to predict oil production.
Multiple point statistics has become a common tool to build models representing geological formations comprising objects characterized by complex geometries such as curvilinear shapes. The idea consists in referring to a training image depicting the expected geological structures, and then in generating images reproducing the multiple point statistics inferred from the training image.
We investigate a substitute to the commonly referenced multiple-point methodologies that was initially developed in computer graphics: it is called texture synthesis. We modify the way it works so that it can handle reservoir simulation issues. Additionally, we focus on its multiscale variant to make it more efficient.
Within this multiscale context, the basic training image is used to create a set of images with decreasing resolutions that are all viewed as training images. Then, a realization is simulated one scale at a time, starting from the level of lowest resolution. When simulating the realization at a given scale, the selection of the value to be assigned to a grid block involves various levels of comparison. We still compare the neighbors of the grid block under consideration with the events extracted from the training image corresponding to the same level of resolution as done for multipoint simulation. In addition, we compare its ancestors with the events extracted from the coarser training images. The ancestors are the values already simulated to populate the coarser grids. In such conditions, the first realization generated at the coarsest scale is able to capture the largest geological objects or heterogeneities. Then, it is used as a constraint that is propagated scale by scale towards the finest resolution grid. This makes it possible to use small size neighborhoods. A few improvements are then suggested to make the algorithm more efficient without deteriorating the simulated images. Last, we present numerical tests performed with complex training images.