Upscaling of Petrophysical Properties Using Wavelet Transforms and its Comparison to Other Methods of Upscaling

TOMUTSA, LIVIU, Lawrence Berkeley National Laboratory, Berkeley, CA

Upscaling of reservoir properties is critical to translate parameters measured from laboratory samples into values representative of the much larger grid blocks used in field simulators. Reduction of the number of grid blocks is neccessary because the total number of blocks that can be used in flow simulators is limited by the computer hardware (Memory and CPU time) as well as the complexity of the process simulated.Conventional upscaling techniques use central values of parameters such as the arithmetic, geometric, and harmonic means that are not robust.Several new methods have been proposed in recent literature that circumvent the problems faced in using the conventional techniques at a small cost of computational time. We have developed a method based on the wavelet transform for upscaling.We use single-phase flow scenarios with synthetically generated heterogeneous flow fields and computed tomography (CT) monitored laboratory flow tests. The laboratory flow studies were performed on a ripple-bedded Bartlesville sandstone block. The block dimensions are 16.7x4.8x7.0 cm. The local permeability measured by probe minipermeametry, CT, and Petrographic Image Analysis (PIA) ranged from 1 to 70 millidarcys. The local porosity values measured by X-ray CT ranged from 9 to 27%. The laboratory data were used as the reference for the comparison of simulations performed on upscaled grids with successive degrees of grid coarsening. We compare the method with a model developed by Kasap and Lake (1990). The advantages and limitations of all the methods are discussed.

AAPG Search and Discovery Article #90911©2000 AAPG Pacific Section and Western Region Society of Petroleum Engineers, Long Beach, California