Separable multiple-point geostatistical modeling of three-dimensional discrete fracture-vug networks Conference Paper uri icon

abstract

  • Copyright © SPE All rights reserved Most of the world's massive fields produce from naturally fractured vuggy carbonate reservoirs. However, modeling such reservoirs is a challenging task due to the co-existence of porous and free-flow domains over a wide range of scales. Realistic characterization of fractured vuggy reservoirs requires preservation of the geological structure and reproduction of patterns. In this study, we model a discrete fracture-vug network using microtomography and multiple-point geostatistics (MPG) modeling technique. For this purpose, micro-CT scan images of a real core is used to generate two micro-scale geological models (2D and 3D reference models, which are used as original training images) with three structures; matrix, fractures, and vugs. The structures in the reference models are also separated into matrix-fracture and matrix-vug to construct two other training images for each of the 2D and 3D original training images. The three training images are then used in MPG to generate multiple equiprobable models that mimic the original networks of the fractures and vugs. The models created using the original training images are called direct models. The others that are generated using the training images after separating the structures (matrix-fracture and matrix-vug), referred to as separable training images, are combined into fracture-vug-matrix models by superimposing the fracture networks from the matrix-fracture models on their corresponding matrix-vug models. These final three-structure models are called the combined models. The spatial continuity, connectivity, patterns reproduction, and flow performance of the generated models are compared with those of the reference models (original training images). The results show that, the separable modeling method produces better results when used in 2D modeling, however, that is not the case for 3D modeling. All the generated realizations preserved the structures and reproduced the spatial continuity of the reference models for 2 and 3D cases. In addition, the patterns are well reproduced in both cases. However, the connectivity and the flow performance of the traditional (direct) MPG method are found to be more accurate in the 3D case than those of the separable MPG method. These results proof that the separable MPG method is not suitable for real 3D naturally fractured vuggy reservoirs modeling applications. However, more detailed sensitivity analysis of the MPG parameters could provide new insights in utilizing this method for 3D reservoir modeling applications.

author list (cited authors)

  • Mohamed, M., Qian, S., Wang, Y., Fraim, M., He, J., Gao, S., & Killough, J. E.

publication date

  • January 2016