The Introduction of the Microchanneling Phenomenon to Cyclic Steam Stimulation and Its Application to the Numerical Simulator (Sand Deformation Concept)

Abstract

Abstract Historically, a vertical or horizontal fracture is believed to be a main recovery mechanism for a cyclic steam-injection process in unconsolidated oil sands. Most current computer models for the process are based on the fracture concept. With the postulated sand deformation concept, on the other hand, the injected fluid is able to penetrate the unconsolidated oil sand by creating microchannels. When the pore pressure is reduced during production, these secondary flow channels will collapse totally or partially. Condensed steam tends to sweep fluids where the bitumen had been heated and imparts mobility as a result of the injected hot fluid. Flow geometry of the new concept is described in this paper. The physical differences between the sand deformation zone and the no-deformation zone are also investigated. The three major differences between these two zones are porosity change, pressure level, and energy and flow characteristics resulting from the existence of microchannels. All these modifications were incorporated successfully into a conventional numerical thermal simulator. The new model provided an excellent match for all the field observations (steam-injection pressure, oil-and-water production rates, fluid production temperature, downhole production pressure, and salinity changes) of a steam-stimulated well in an unconsolidated oil sand. The study indicates that the most important phenomenon for in-situ recovery of bitumen is the one-way-valve effect of the microchannels, which are opened during injection and closed during production.