The development of oil sands reservoirs with Steam Assist Gravity Drainage (SAGD) is a capital intensive investment. It is crucial to improve the economic value through all aspects of the value chain, from reservoir, facility to end selling points. There are many studies focusing on optimizing the performance of single SAGD well pairs. However, few are looking into optimizing the overall economy of the development of large scale oil sands reservoirs.
This paper presents a case study of the value improvement process of an Athabasca oil sands reservoir to be developed with the SAGD process. The reservoir has various quality and a size of accommodating about 200 well pairs with 100m well spacing and 800m well length. The purpose of this paper is not to cover all value improvement aspects but from a subsurface engineering point of view to optimize reservoir development and production operation parameters to improve the overall reservoir development value. The investigated parameters include well spacing, steam injection pressure, artificial lift method, wind-down and blow-down criteria, and minimum oil rate of edge wells. In the process, reservoir simulation is fully integrated with economic evaluation. The optimization and decision are made based on economic assessment results, operation requirements and environmental benefits. In the value improvement process, both type well and full field reservoir simulation were used to forecast full field production for economic evaluation. Since the pad sequence also plays an important role in the reservoir development economy, to improve Net Present Value (NPV), a simple SAGD economic index is proposed and applied for pad ranking. The ranking results are compared with the pad-by-pad economic evaluation that included all economic elements but taxes. Through all these efforts, the NPV of the project was significantly improved.