Experimental and Simulation Study of In-situ Combustion Process in Carbonate Fractured Porous Media

摘要

According to difficulties of producing heavy oil reservoirs, in-situ combustion (ISC) as one of the high efficient methods leads to reduce oil viscosity by increasing temperature. Since there are remarkable amounts of heavy oil reservoirs in the world and lots of experimental works have been carried out on sandstones, shale or oil sands, the research on carbonate rocks seems to be rare. The experimental tests were performed with the oil of 17.5° API and 8° API mixed with the crushed carbonate rocks of Asmari and Sarvak formations respectively to investigate the feasibility of ISC and calculate its parameters. According to experiments, combustion tube conducted vertically to use gravity as a force to minimize gravity segregation effects. Results show that combustion is technically applicable to the both rock-fluid systems. Additionally the percentages of CO2, O2 and CO have been measured by gas analyzer. Moreover, the effect of grain size on combustion temperature, connate water on oil recovery and front characteristics are investigated. Finally, fractured model of combustion tube is simulated and the effects of air injection rate, permeability, initial oil saturation and grid size are investigated. The obtained basic parameters of experiments are suitable for ISC implementation to fields efficiently.