Experimental Investigation of In Situ Combustion for Heavy Oils at Low Air Flux.

摘要

In order to conduct a successful in situ combustion oil recovery project, sustained propagation of the combustion front within the reservoirs is a must. Sufficient air must be supplied to maintain the propagating combustion front in the carbon oxide forming mode otherwise unfavorable low temperature oxidation reactions will consume oxygen and not mobilize oil. When this happens, the combustion process is deemed to be exhausted.;Quantification of the minimum air flux required for sustaining combustion zone propagation is needed to properly match the capacity of the air injection facility to the volume of reservoir which is to be swept by the thermal zone.;One-dimensional combustion tubes are conventionally used to obtain important combustion parameters required for designing an air injection project. Due to the high heat capacity of laboratory equipment designed for elevated temperature and pressure operation, oxygen addition reactions are promoted by the heat transfer through the core holder walls when the laboratory tests are performed at low air injection rates. Therefore, when operated at elevated pressures, the combustion tubes are unable to operate at the low air fluxes required to establish the minimum possible air injection flux while maintaining the combustion reactions in an effective mode.;In an attempt to address this issue, a state of the art combustion cell was conceived and utilized as a way of addressing the above mentioned constraints associated with high pressure one-dimensional combustion tubes. The new design enables continuous air flux reductions without having to adjust the air injection rate and as such allows for determination of the minimum flux for specific oils under conditions which are representative of a field scale operation. This research proves that experiments involving core from a typical Athabasca Oil Sands reservoir showed air injection processes, when operated at favorable conditions have the ability to propagate through the heavy oil reservoirs at high temperatures and at injection air fluxes (based on the air injection rate and area at the downstream front location) of under 1 sm3/m 2˙h.;This thesis presents a new approach to studying in situ combustion processes. It describes the nature of the combustion zone under a variety of conditions and air fluxes approaching those experienced in field projects and provides important information on the nature of reactions and the physics of the process which must be considered when attempting to predict combustion front exhaustion using a numerical simulator. It also gives insight into the limitations in laboratory investigations of in situ combustion as well as the expected behavior of field applications of the in situ combustion process.