CAUSES OF PERMEABILITY VARIATION IN A LOWER CRETACEOUS RESERVOIR UNITIN THE WEST SIBERIAN BASIN, RUSSIA

Samples of the Lower Cretaceous BS10 reservoir, taken from 11 oil fiel ds in the central part of the West Siberian Basin, show a permeability variation of more than 4 orders of magnitude at the scale of the core plug. Much of this variation occurs in samples that fall within the f ine-grained Wentworth class. However, application of 2-D Fourier analy sis and other methods of petrographic image analysis demonstrates the existence of a real, but subtle, variation in grain size that provides an important control on permeability. Reservoir quality will be best in the facies that represent the highest depositional energy. (C) 1996 Elsevier Science Ltd.