SAGD Performance Optimization Through Numerical Simulations: Methodology and Field Case Example

Abstract

Abstract SAGD is a very promising recovery process to produce heavy oils and bitumen resources. The method ensures both a stable displacement of steam and economical rates by using gravity as the driving force and a pair of horizontal wells for injection/production. After several years of small scale field tests (pilots), the method is now considered as mature and large scale projects are scheduled in a near future (in Canada for instance). Nevertheless, both technical and economical success of the process require a satisfactory development of the steam chamber, which can be achieved by well monitoring (i.e. steam trap control). This paper presents a general methodology based on numerical investigations to obtain and maintain an optimized development of the chamber throughout the production life of the wellpair. First, the methodology is explained on a synthetic case and applied to a real field case example. Field data are first history matched with the model and then the proposed approach is used to evaluate how the oil production could have been enhanced and optimized further. It is shown that an optimized steam chamber development is obtained by adjusting the steam injection rate to the potential of the reservoir (fluids and geology) and by monitoring the production rate during the process/operations to keep the steam chamber as large as possible but away enough from the production well to prevent any steam breakthrough. The results are in good agreement compared with Butler's analytical model (oil rate and steam chamber shape). A very good history match is obtained in the field case example. The proposed methodology shows that oil production rate can be doubled when injection/production rates are adapted to the SAGD reservoir potential.