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Horizontal permeability anisotropy developed from the upscaling of anisotropic facies patterns

Conference · · AAPG Bulletin (American Association of Petroleum Geologists); (United States)
OSTI ID:7017374
;  [1];  [2]
  1. Elf Aquitaine, Pau (France)
  2. Ecole des Mines, Nancy (France)
Traditionally, the size and shape of grid blocks owe more to the limitations of numerical simulation procedures than to any consideration of geological heterogeneity. Geological systems, and hence associated permeability and porosity fields, are inherently complex, being characterized by nested levels of heterogeneity. Moreover, for directionally dependent variables, such as permeability, a heterogeneous nature at small scales will lead directly to anisotropy in average (or measured) values at larger scales. The representation of geologically complex volumes as individual horizontal and vertical permeability values has long been recognized as a necessary simplification. Recent advances in stochastic modeling have vastly improved the representation of complex geology in unknown interwell regions. The high level of detail provided by such models often requires several million grid blocks. This degree of detail cannot, however, be used in flow simulations, and hence, scaling up is necessary. The difficulties in scaling up of rock-property data are based on the conflicting requirements of significantly reducing the number of grid blocks, while maintaining a reasonable degree of detail in the representation of heterogeneity. To analyze whether grid blocks adequately represent complex heterogeneities the authors constructed complex, geologically realistic channel-levee complexes, using an object-modeling (Boolean) approach. This approach has the advantage over reservoir, or outcrop, derived data in so much as the 3-D architecture is fully known. The disadvantages are that the realizations are too simplistic, not necessarily geologically realistic, and contain only one scale of heterogeneity. In the present context, however, simplification of both geological and scale-related heterogeneities can be seen as advantageous in the interpretation of the results.
OSTI ID:
7017374
Report Number(s):
CONF-940803--
Conference Information:
Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 78:7
Country of Publication:
United States
Language:
English