Optimal Amount of Solvent in Solvent Aided Process

Abstract

Abstract The Solvent Aided Process (SAP), described previously in literature, is an improvement to SAGD that promises to enhance the economics of bitumen/heavy oil recovery projects and reduce their impact on the environment. In SAP, a small amount of hydrocarbon solvent (such as a low molecular weight alkane) is introduced as an additive to the injected steam during SAGD. The viscosity of the oil thus is reduced due to solvent dilution in addition to heating. SAP can significantly improve the energy efficiency of SAGD, thus reducing the heat requirement. Cenovus's field trials of SAP, discussed elsewhere, have shown the practical upside of this process. Modeling predicts that the higher the amount of solvent used in SAP, the better is the performance (rates, energy intensity) of the recovery process. Besides rate of Bitumen production, economics of SAP depend on the availability and cost of solvent. Although the existing literature has discussed deterministic variations in solvent input, it is largely silent on how much solvent is the right amount of solvent in SAP. This paper contains discussion of using optimal amount of solvent with steam in SAP. The discussion is based on modeling and compares performance of the scheme under various solvent injection strategies. It explores effect of temporal variation in the concentration of solvent at the vapor-liquid interface as well as of pulsed solvent injection on the performance of the process.