Optimal Well Placement for Heavy Oil and Bitumen Reservoirs with Vertical and Lateral Oil Mobility Distributions

Darcy s law shows that the primary control on gravity-driven bitumen speed within oil sands reservoirs is<br>oil mobility, the quotient of oil effective permeability and viscosity. The controlling factors on oil<br>effective permeability are absolute permeability and oil relative permeability which in turn depends on oil<br>saturation. The controlling factors on oil viscosity are temperature and composition which in turn is set by<br>the amount of solution gas, reservoir geology, charge rate, biodegradation and diffusion of light end<br>components, availability of water for biodegradation, and temperature history. The absolute permeability,<br>rock type (relative permeability), fluid saturations, and compositions are all heterogeneous in oil sands<br>reservoirs with differing variability in vertical and lateral directions. Current thermal recovery processes<br>such as SAGD use straight wells that are convenient for drilling and planning but are not optimized with<br>respect to oil mobility distribution. This research examines what the optimum SAGD wellpair trajectory<br>would be in a fully heterogeneous reservoir. The research not only reveals that the optimal well trajectory<br>may not be straight but that injectors and producers need not be parallel to each other.