Experimental Study on the Variations of Oil Sand Permeability during SAGD Processes

Abstract

The M oil block in Canada contains different sand bodies, and sand bodies with more developed argillaceous interlayers tend to hinder the development of steam chambers in steam-assisted gravity drainage (SAGD), which ultimately leads to lower recovery than expected. Previously, most core flooding experiments for SAGD experimental research were done using sandpacks, while a few literature studies were found to study the oil sand reservoir using natural core samples due to its brittleness after oil washing and its difficulty to operate. In this study, natural oil sand cores belonging to different sand bodies were used to carry out laboratory experiments of steam injection into water-saturated cores, combined with mineral composition testing and computed tomography (CT) scan tests to study the influence of steam temperature, steam injection flow rate, and initial core permeability on liquid permeability of reservoirs. The permeability reduction rates of different sand bodies under the same experimental conditions were also compared, which shows the impact of sedimentary facies on production. The results show that liquid permeability of reservoirs decreases as temperature increases and as the steam injection flow rate increases. The higher the initial gas permeability of a reservoir, the lower the permeability reduction rate. The permeability of the estuary sand bar is generally higher than the tidal flat sand body and is expected to have a less permeability reduction rate during steam injection. This study provides important information for parameter optimization design and development of oil sand reservoirs.