Improving the SAGD Performance by Introducing a New Well Configuration

Abstract

Summary Steam-assisted gravity drainage (SAGD) is a commercially successful recovery process that produces heavy oils and bitumen. The method ensures both a stable displacement front of steam and economical rates by using gravity as the driving force with a pair of horizontal wells for injection/production. Although several ways of improving the performance have been discussed in the literature, the well configuration employed in the process has remained the same as originally proposed by Butler et al. (1981). A systematic attempt to improve the performance by using radically different well configurations has not been reported. This paper presents a study intended to examine the applicability of a new well configuration to SAGD processes in Athabasca and Cold Lake reservoirs in central and northern Alberta. The fully implicit thermal-reservoir simulator, CMG's STARS 2007, with fully coupled wellbores was used to account for frictional pressure drop and heat losses along the wellbore. 3D numerical simulation models were set up, and sensitivity analyses were conducted on injection pressure. After optimization of the injection pressure, an investigation of new well configurations was conducted using these models. The result of this work shows that the SAGD-process performance in Athabasca and Cold Lake reservoirs can be improved significantly by changing the well configuration.