A Subcool Reactive ICD for Optimization of SAGD Wells

Abstract

Abstract A novel Flow Control Device (FCD) for Steam Assisted Gravity Drainage (SAGD) production wells is presented. This device increases the thermal efficiency of the process and accelerates bitumen recovery by passively increasing its flow resistance as the produced fluid's subcool decreases. Passive FCDs have been widely employed in SAGD applications to reduce the cumulative steam/oil ratio (C-SOR) and increase bitumen production. These passive devices react to density and/or viscosity changes of the produced fluid but do not select against steam. However, the novel FCD presented in this paper reacts specifically to the subcool of the produced fluid and offers a greater restriction as the produced fluid approaches the saturation curve and attains a steam component. Computational fluid dynamics (CFD) and experimental data have been used to minimize frictional pressure loss through the FCD while inducing subcool choking in pressures and flow rates typical of SAGD wells. Selected test data clearly shows that the novel FCD increases its resistance sharply as the subcool approaches zero and as a steam component becomes present in the produced fluid. From initial hot water testing and extensive steam testing, a mechanistic model has been developed that uses physics and geometry to predict the performance of the device under a wide variety of thermodynamic conditions. The test data and this model were fed into numerical reservoir simulators to visualize the effects of this device in a typical SAGD completion. These simulations clearly show improved C-SOR and a more fully developed steam chamber for completions that utilize this novel FCD. The novelty of this FCD is its proactive, yet passive, means of preventing steam production in SAGD wells. By preferring more subcooled fluid – either cooler or higher pressure – steam breakthrough and hot-spotting will be prevented or controlled, downhole equipment will be protected, and the SOR will be reduced. The thorough, mechanistic model for the new FCD allows for accurate interpolation and meaningful extrapolation, along with seamless integration with reservoir simulators to evaluate deployment strategy on a case-by-case basis.