Block to block interactions and their effects on miscibility gravity drainage in fractured carbonate reservoirs, experimental and analytical results

Several experiments were carried out to investigate the immiscible and miscible gravity drainage performance in a stack of matrix blocks. Both gas/oil and solvent/oil systems were studied in these experiments. The results indicated that for the gas/oil system, oil infiltration into lower blocks happens quickly. Also, when an oil-filled matrix block is surrounded by a solvent in a tilted fracture, relatively fast convection currents are possible due to, effective mixing of the fluids inside the fracture system. Consequently, the oil is produced at rates much higher than the one predicted by a single block. Finally, re-pressuring the reservoir may give a faster response than enriched gas injection for the same ultimate recovery. Combination of the concepts block to block fluid flow behavior in gravity drainage setting by quantifying the rate of infiltration, gravity segregation and mixing with or without solvent injection at different degree of miscibility in fractured reservoirs is a further step than the previous works in this research area. The application of these results to a real carbonate reservoir is also discussed.