Effects of Well Placement using Multi- Segmented Wells in a Full Field Thermal Model for SAGD: Athabasca Oil Sands

Standing at 2.5 trillion barrels, Canada has the largest portion of the world’s ultra-heavy oil and bitumen resources. While shallow heavy oil reserves are extracted from pit mines, deeper reserves can only be extracted through wells. Production requires Steam Assisted Gravity Drainage (SAGD) and Cyclic Steam Simulation (CSS) methods. The optimal placement of wells defines the propagation of steam within the reservoir and the resulting flow of crude towards the producers. A full field thermal model was developed using Petrel* Reservoir Engineering to simulate the SAGD recovery process for Athabasca Oil Sands. This study was conducted to observe the behavior of the SAGD process under a full field environment with multiple pairs using an advanced well model. This model divides the wellbore into multiple segments, where each segment acts as an individual connection to the reservoir. This method allows for the simulation of complex multi-phase flow effects such as counter-flow in slowly flowing horizontal wells, fluid fall-back, variable well-bore storage and friction. Sensitivity analysis on parameters, such as well spacing (inter-well and horizontal) and steam injection rates combined with the complex well model allowed a true simulation of a SAGD process in a full field environment. Software programs including Eclipse Parallel optimization and the John Appleyard Linear Solver (JALS) * were used to run multiple simulations in less time. This paper describes the process and the sensitivity analysis used to design various SAGD models. The impact of using Multi-Segmented Wells and the effects of a full field model on the steam chambers are also discussed.