Key words: Western Siberia, Archinskoye oilfield, Paleozoic, carbonate sediments, field development optimization.
Conceptual geological cross-section of Archinskoye gas–oil field is considered, which is shown to be carbonate sediment fractured in a varying degree. Fracture network provides hydraulic connectivity between bodies of cavernous and porous rock through the reservoir at macroscopic scale. According to available information the main direction of faults and joints in the Southern block of the field is believed to be parallel to the tectonic compression axis. This allows expecting high hydraulic conductivity of faults in the block. This is reverse situation to the Northern Block where orientation of faults is perpendicular to the compression axis which leads to low expected conductivity of the faults. Fracture network on Archinskoye field plays the twofold role: on the one hand it enhances permeability and connectivity of the reservoir and provides economical production rates; on the other hand it increases the risk of early water breakthrough during injection phase and gas coning towards well in under-gas-cap zones. These factors reduce the ultimate recovery. It is shown that effective velocities of fluid interfaces are controlled mainly by the void space structure constructed of fracture intersections.
