A FAST ALGORITHM FOR ESTIMATING LARGE-SCALE PERMEABILITIES OF CORRELATED ANISOTROPIC MEDIA

The problem of estimating large-scale permeabilities of reservoirs bas ed on knowledge of the small-scale permeabilities is addressed. We pre sent an accurate and fast algorithm to calculate the global permeabili ties of two- or three-dimensional correlated and anisotropic block sam ples, thus providing a fast algorithm for obtaining grid block permeab ilities for reservoir simulators from small scale data. The algorithm is tested on both two- and three-dimensional tube networks generated f rom real images and fractal forgeries modeling porous media. In almost all cases, the algorithm estimates the correct global permeability (c alculated using exact but slow algorithms) of the network to better th an 5%. The new algorithm is comparable in speed to conventional averag ing techniques, such as the geometric mean, but the obtained estimates are always much better.