Steam-assisted gravity drainage is an effective recovery method employed to shallow heavy oil reserves to increase the amount of recoverable oil in place. To ensure effective recovery, seismic monitoring of an active steam flood is essential in delineating the location of stimulated reserves. Typically, large and dense 4D reflection surveys are recorded to trace the motion of the steam flood, observable in terms of time-shifts and amplitude difference. However, time-lapse refraction profiles can be employed to monitor the movement of an active steam flood within a reservoir in a manner similar to that of 4D reflection profiles. Through the reciprocal traveltime analysis, refraction profiles can delineate significant time-shifts within a monitor survey due to the injection of a steam flood.
Time lapse refraction profiles have significantly lower time and monitory commitments than conventional 4D reflection profiles. Refractions from the Devonian carbonates can be recorded at large offsets (~700m), thus requiring fewer sources to survey an extensive area. This study will outline the basis for 4D refraction surveying through simple numerical modeling of a shallow, heavy oil reservoir.
View full article as PDF (1.32 Mb)