Feasibility Study of Autoignition Process in Heavy-Oil Reservoirs

Abstract

Abstract Heavy oil is an important part of the energy resource in the world. With today's increasing demand for energy resources, heavy oil recovery is under great attention. Heavy oil deposits in Middle East are in fractured carbonate-type reservoirs that have not been studied in the literature. One of the important factors in the feasibility of in situ combustion (ISC) on a heavy oil reservoir to sustain fireflood is the auto-ignition temperature under reservoir conditions. In this study, the kinetic model of different heavy oil samples from South West Iran mixed with silica sand or crushed carbonate rock and clay were studied using Thermogravimetric Analyzer (TGA) and Differential Scanning Calorimeter (DSC) techniques. The reactions were carried using air enriched with different percentages of oxygen. Two sets of experiments for the combustion of crude oil samples were carried out by TGA equipment for the determination of auto-ignition temperature. In the first, the system was operated non-isothermally with a linear temperature rise 10°C/min; while in the second the reaction was conducted isothermally at different temperatures. In both kinds of experiments the CO, CO2, hexane and propane in the exhaust gases from the TGA, were measured by an Infrared Analyzer (IR). Based on the TGA runs performed, it is concluded that auto ignition was related to the percentage of enriched air for both the silica sand and carbonate rock in the presence of clay. In addition, as expected in DSC run under non-isothermal Low Temperature Combustion (LTC) and High Temperature Combustion (HTC) reactions clearly reveal exothermic peaks.