Permeability anisotropy developed from the up-scaling of anisotropic channels. Impact on waterflooding simulation results

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:207321

Massonnat, G J ^[1]

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1. SPE, Richardson, TX (United States)

Geological systems, and hence associated permeability fields, are inherently complex, being characterized by nested levels of heterogeneity. These geologically complex volumes are represented in the reservoir models for flow simulation by equivalent homogeneous medium grid blocks. Traditionally, this necessary simplification leads to under-estimate geological and petrophysical heterogeneity, as the reservoir is dicretized in coarse grid-blocks which size and shape owe more to limitations of numerical simulation procedures than to any consideration of geological heterogeneity. Recent advances in reservoir characterization and stochastic modelling have vastly improved the representation of complex geology and petrophysics 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 utilized by flow simulators, and hence, scaling-up is necessary. Scaling up absolute permeabilities is a delicate point since averaging heterogenous values, even isotrope at fine scale, develops anisotropy at the larger scale. The memory of the pre-up scaled heterogeneities is, therefore, included into all the members of the permeability tensor (diagonal and crossed members). However, most of the flow simulators work only with the diagonal members of the permeability tensor and, in this case, a whole part of the information concerning heterogeneity is {open_quotes}lost{close_quotes} in the up-scaling phase. Then, the difficulty in scaling-up of rock-property data are based on the conflicting requirement of significantly reducing the number of grid blocks, whilst maintaining a reasonable degree of detail in the representation of heterogeneity. This is critical for all fields for which the driving heterogeneties in a coarse grid model must be preserved in order to correctly represent the flooding mechanism and the swept area.

• OSTI ID: 207321
• Report Number(s): CONF-951002--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
ANISOTROPY
ENHANCED RECOVERY
PERMEABILITY
PETROLEUM
PRODUCTION
RESERVOIR ROCK
WATERFLOODING