Low-Temperature-Oxidation Kinetic Parameters for In-Situ Combustion: Numerical Simulation

Summary The principal objective of this study was to provide low-temperature-oxidation (LTO) reaction models that are suitable for use in numerical simulators of in-situ combustion for bitumen and heavy-oil reservoirs. A systematic study investigated the LTO reactions of the liquid-phase components of bitumen and heavy oils. Athabasca bitumen, free of water and minerals, was oxidized by use of a laboratory-stirred semiflow batch reactor. Kinetic studies were carried out in the 333 to 423 K [140 to 300°F] temperature range and at an oxygen partial pressure of 50 to 2233 kPa [7.3 to 324 psi]. The total pressures applied in the reactor ranged from 2190 to 4415 kPa [318 to 640 psi]. Experimental data were collected in the kinetic subregime. Reactor product gas was analyzed with a gas Chromatograph, and the liquid-phase oxidation product was separated into six main components (lumped or pseudocomponents): saturates, aromatics, Resins 1, Resins 2, asphaltenes, and coke (SARA). Kinetic models are established for the liquid-phase LTO reactions. The models involve further lumping of the pseudocomponents. Saturates and aromatics are lumped to form the maltenes, Resins 1 and 2 to form the resins, and asphaltenes and coke to form asphaltenes/coke components. On the basis of experimental kinetic data, two main types of reaction models are proposed: (1) a non-steady-state kinetic model representing the overall rate of oxygen consumption and (2) four non-steady-state multiresponse kinetic models representing the oxidation reactions of the liquid-phase components. Proposed models were found statistically adequate and suitable for use in numerical simulators.