The top down In-Situ Combustion (ISC), involves the stable propagation of combustion front from topvertical injector to the bottom horizontal producer. Besides laboratory studies in conventionalsandstones, no application of the process in fractured carbonates has been addressed yet. In this paper asuccessful combustion tube experiment and history match of Iranian low permeable fractured heavy oilreservoir called Kuh-E-Mond, is presented and accompanied with details of experimental and simulationmodel. Validated model has been modified further to investigate the feasibility of Top-down ISC infractured reservoirs mimicking block scale combustion cells. Effects of fractures geometrical propertiessuch as orientation, location, extension, density, spacing, disconnection and dispersion have beenconsidered. Investigation of aforementioned geometrical properties performed for the case of presenceof networked fractures (presence of both vertical and horizontal fractures). Results confirmed higheroutcome in the case of optimum vertical or horizontal fractures density and spacing. Laterally locatedvertical fractures enhanced the process in terms of ultimate oil recovery and sweep efficiency. Longervertical fractures and higher degree of fractures dispersion through the reservoir improved the recoveriescompared to the case of extended horizontal fractures and higher degree of horizontal fracturesdispersion through reservoir. Depending on the reservoir parameters (such as fracture and matrixpermeability) there is an optimum length of vertical fracture in which it enhances the recovery. Thismeans very long extension of vertical fractures could cause early oxygen breakthrough and as a resultlower sweep efficiency and oil recoveries. Simulation analysis revealed that Top-down In-SituCombustion has higher feasibility for the reservoirs with highly networked fractures such as thoseoccurring in the Persian Gulf coast.
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