The principal objective of this study was to provide low temperature oxidation (L.T.O.) reaction models which are suitable for use in numerical simulators of in situ combustion for bitumen and heavy oil reservoirs. A systematic study was carried out to investigate the L.T.O. reactions of the liquid phase components of bitumen and heavy oils. Athabasca bitumen, free of water and minerals, was oxidized using a laboratory stirred semiflow batch reactor. Kinetic studies were carried out in the 60C to 150C temperature range and at oxygen partial pressure of 50 kPa to 2233 kPa. The total pressures partial pressure of 50 kPa to 2233 kPa. The total pressures applied in the reactor ranged from 2190 kPa to 4415 kPa. Experimental data were collected in the kinetic subregime. Reactor product gas was analyzed using a gas chromatograph and the liquid product gas was analyzed using a gas chromatograph and the liquid phase oxidation product was separated into six main components phase oxidation product was separated into six main components (lumped components): saturates, aromatics, resins I, resins II, asphaltenes and coke. Kinetic models are established for the liquid phase reaction components involved in the L.T.O. reactions of a mixture of complex hydrocarbons. Based on the experimental kinetic data, two main types of reaction models are proposed. These are:A non-steady state kinetic model to represent the overall rate ofoxygen consumption.Four non-steady multiresponse kinetic models representing theoxidation reactions of the liquid phase components. Proposed models were found statistically adequate and are Proposed models were found statistically adequate and are suitable for use in numerical simulators. Introduction Several articles have been published describing in situ combustion processes and giving detailed results of laboratory and field experiments. The methods that have received extensive studies are dry forward combustion, wet forward combustion and reverse combustion. It is documented that the performance of these processes depends on the L.T.O. reactions accompanying the in situ processes depends on the L.T.O. reactions accompanying the in situ combustion operations. Furthermore, results of published laboratory and field studies indicate that more meaningful analysis of combustion data cannot be made until the L.T.O. reaction kinetics are studied and the reaction mechanism elucidated. Consequently, a reliable numerical simulator for performance prediction or for evaluation of the in situ combustion processes must model adequately the L.T.O. reactions. The simulator should include a L.T.O. reaction model able to do the following:represent the overall rates of oxygen consumption;represent the major reaction components and products in the liquidphase and their individual rates of transformations. Most studies reported in the literature have considered only the overall rates of oxygen consumption for the L.T.O. reactions of crude oils. Summaries of these studies have been published. The kinetics data presented in this study were measured on bitumen from the Athabasca oil sands formation. oil sands were obtained from the Suncor mine in Fort McMurray, Alberta. The bitumen was extracted from the sand using toluene as a solvent. Table 1 summarizes the properties and composition of the original bitumen sample. Efforts were directed, in this study, towards building mechanistic type models rather than empirical ones. The intricate chemical nature of the oil sands bitumen suggests immediately that the reaction mechanisms involved in L.T.O. reactions are many and complex.

Multiresponse kinetic models are established for the low-temperature oxidation (LTO) reactions of Athabasca oil sands bitumen. The models provide adequate description of the overall rate of oxygen consumption and of the reactions of the liquid phase bitumen components.The LTO models are suitable for use in the in sifu combustion numerical simulators of the oil sands. SCOPESeveral articles have been published describing in sifu combustion techniques and giving detailed results of laboratory and field experiments. These papers include: Alexander et al. (1962), Bennion et al. (1977), Burger and Sahuquet (1973). Cram and Redford (1977), Dietz (1 970), Dietz and Weidjema (1 968), Morse (1 976), Nelson and McNiels (1956), Showalter (1963), Smith and Perkins (1973), Reed et al. (1960), andWalter (1977). The performance of in situ combustion processes depends on the accompanying low-temperature oxidation (LTO) reactions (Alexander et al., 1962;Dabbous and Fulton, 1974;Burger and Sahuquet, 1973). Furthermore, results of published laboratory and field studies indicate that more meaningful analysis of combustion data cannot be made until the LTO reaction kinetics are studied and the reaction mechanisms elucidated. Consequently, a reliable numerical simulator of the in situ combustion processes must model adequately the LTO reactions. The simulator should include an LTO reaction model able to do the followCorrespondence concerning this paper should be addressed to K. 0. Adegbcsan, who is now with Esso Rcsourca Canada Ltd.

Production performance of Esso Resources Canada Limited’s Horizontal Well Pilot I (HWPI), recovering10 degree API bitumen from Cold Lake, is described. The well has utilized a vertical steam injection well since 1980. Over 50,000 m3 of bitumen have been recovered at a cumulative oil-steam ratio (OSR) of over 0.35 during the first eight years of operation. A comprehensive field monitoring program of HWPI was undertaken including well bottomhole pressures and temperatures, reservoir temperatures, interwell radioactive tracer tests, surface seismic surveys and cased hole logs. Approximately 20 to 30 percent of the original bitumen in place in a thermally drained zone, inferred from measured surface seismic data, was recovered. A wellbore utilization of approximately 98 meters or 40 percent of the total horizontal slotted liner length was estimated based on the surface seismic anomalies and bitumen production data. This finding was confirmed from the results of a successful numerical simulation history match of this pilot. Analytical models have identified that pressure drive mechanisms dominated the early life of the well, with gravity drainage accounting for most of the production later in the well’s life.

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