화학공학소재연구정보센터
Journal of Canadian Petroleum Technology, Vol.46, No.9, 57-61, 2007
Effect of solvent Sequencing and other enhancements on solvent aided process
Alberta's oil sands clearly present an economical solution to the world's dwindling conventional oil supply. Over 80% of these oil sands can only be recovered by in situ methods, such as SAGD technology. However SAGD, in its current commercial form, is an energy intensive process. The authors have previously described an improvement to SAGD-Solvent Aided Process (SAP)-that aims to combine the benefits of using steam with solvents. In SAP, a small amount of hydrocarbon solvent is introduced as an additive to the injected steam during SAGD. SAP holds the promise to significantly improve the energy efficiency of SAGD, thus reducing the heat requirement. Previously discussed results from Encana's field trials of SAP have shown the practical upside of this process. In theory, a variety of solvents can be employed with steam to tap the benefit of solvent dilution in combination with (in situ) heating the oil. However, due to their commercial availability, light alkanes present in the natural gas condensate are the practical choice for this purpose. These different solvents can be used individually or as a mixture, together or sequentially, with varying degrees of benefit. The economics of a SAP project depends on the enhancement of oil recovery and rates as well as solvent recovery. This paper, based on modelling work, investigates the effect of solvent sequencing, the impact of cross-flow of gas on solvent recovery, the effect of low pressure operation on SAP performance and the operation of SAP in bottom-up geometry. Based on this work, the performance of SAP can be improved by employing proper sequence of solvent, cross-flow solvent recovery and low pressure operation. Bottom-up SAP takes the bitumen recovery to new levels of energy efficiency with steam-oil ratios below 0.5.