The effect of pressure on oxidation kinetics of tar from a tarmat reservoir

The oxidation kinetics of a tar with physical and chemical characteristics similar to those of a reservoir tar were studied employing a variable-temperature oxidation reactor. Mixed with clean, loose sand, the tar showed oxidation behavior typical of heavy crudes with LTO and HTO peaks in oxygen consumption. Higher pressures caused larger LTO-oxygen consumption, lower HTO-oxygen consumption, lower HTO-peak temperatures, higher apparent H/C ratio of fuel, and lower HTO activation energy. All these effects are attributed to suppression of light-end evaporation at low temperatures. Compared with clean sand, natural crushedcore material promoted LTO of the tar but did not alter HTO parameters significantly. With HTO-peak temperatures and activation energies above 500°C and 100kJ/mol, respectively, the tar is not expected to provide for sustained in-situ combustion in the reservoir.