Abstract: The producing mid-Jurassic sandstones in the Baka oilfield have an average matrix permeability of 0.3×10-3μm2.Within these sandstones four kinds of fractures have been recognized. With fractures providing the major passage for fluid flow, these sandstone reservoirs fall into the fractured-porous category. Field survey and statistical data from core measurements indicate that the distribution of fractures is principally controlled by lithology, bed thickness and stress conditions, the geometry of matrix blocks is a function
of fracture type and the combination of fracture types, and the size of matrix blocks is controlled by the frequency of fractures. The conceptual model of fracture distribution is proposed.

Key words: Middle jurassic series, distribution, Network, Fractures, Sandstone, Baka oilfield, Turpan-Hami basin