--> Abstract: Upscaling Core Plug Data to Reservoir Modelling Grid: A Small-Scale Heterogeneity Modelling Approach; #90063 (2007)

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Upscaling Core Plug Data to Reservoir Modelling Grid: A Small-Scale Heterogeneity Modelling Approach

 

Wen, Renjun1, Philip Ringrose2, Kjetil Nordahl3 (1) Geomodeling Technology Corp, Calgary, AB (2) Statoil R & D, 7005 Trondheim, Norway (3) Statoil ASA, Trondheim, Norway

 

Core plugs are direct measurements of reservoir rocks and, therefore, represent the most quantitative information about the reservoir. However, use of core plug data in reservoir models is a major challenge due to sample bias (a core plug represents a tiny fraction of the reservoir). Petrophysical properties at core-plug scale are primarily controlled by mm- to cm-scale bedding structures. Conventional reservoir modelling workflows integrate core plug data into full-field grids by statistical methods that ignore the effects of mm- to cm-scale heterogeneity. To increase the accuracy of reservoir property models, we developed a workflow for upscaling petrophysical models from core plug scale to simulation grid scale.

 

The modelling method consists of two steps. First, we simulate bedding structure grids by modelling bedform migration, deposition and erosion processes. Second, the bedding structure grid is populated with rock properties, such as porosity and permeability, which can be derived from core plug data and/or high-resolution well log data.

 

Stacking of different bedding structures can generate a near-well-bore heterogeneity model with a grid cell size of about 1 mm3. The net-to-gross ratio and porosity data can be conditioned to core or log data. Directional permeability (kx, ky, kz) and relative permeability at the bedding structure scale (0.1 to 1 metre) is calculated by upscaling the mm-scale model using fixed, linear or periodic boundary conditions. Rock type curves, facies-dependent kv/kh and effective property values can be derived from the upscaling results of multiple bedding structure realizations.

 

Since a litho-facies is an association of bedding structure types, the upscaled properties from the bedding structure models can be assigned to full-field facies model grids. The resulting models account for small-scale heterogeneity and can be applied to flow simulations. Case studies demonstrate that small-scale modelling and upscaling can improve accuracy of reservoir simulations and production profile forecasting.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California