Investigating heavy oil solution gas drive fluid properties and the effect of scale on depletion experiments.

摘要

Heavy oil reservoirs throughout the world are produced under solution gas drive mechanism, whereby oil production comes from energy inherent in the reservoir, as pressure drops and gas leaves solution with the oil. This has been observed in Canada's vast heavy oil resources in Alberta and Saskatchewan. Heavy oil solution gas drive mechanisms result in higher than Darcy predicted production and recovery, and better pressure maintenance within the reservoir.;Sand pack depletion results indicate that nucleation does not occur simultaneously throughout the sand pack; instead, it is a localized phenomenon. Low sand permeability causes slower pressure propagation throughout the sand, which results in slower nucleation of gas and lower recovery than higher permeability sands. In addition, gas saturation does not increase uniformly within the sand. Although the physics of foamy oil flow are captured in short cores, longer experimental systems show a more complete pressure decline response. As such, the gas in oil dispersion does not occur across the entire sand pack, and rates and recoveries will be more representative of field values.;This research studies solution gas drive in heavy oil reservoirs. Heavy oil crude properties were measured using visualization CT scanning techniques and nuclear magnetic resonance techniques. Sand pack depletion experiments were also performed on different lengths in order to observe the foamy oil response with declining pressure. Understanding the effect of length on heavy oil solution gas drive may aid in scaling experimental observations to the field. Also, two 18 m long experiments were performed with different permeabilities to better understand the effect of sand permeability on the production and pressure response.