The Dynamic Performance Evaluation of the New Generation of Outflow Control Devices Autonomously Controlling the Conformance of Injection Fluids

Abstract

Several techniques have been applied to improve fluid conformance of injection wells to increase water flooding performance and eventually field oil recovery. Normal outflow control devices (OCDs) are effective solutions for this problem in reservoirs with static properties, however, they fail in reservoirs with complex/dynamic properties including growing fractures. There, the continuously increasing contrast in the injectivity of a section with the fractures compared to the rest of the well causes diverting a great portion of the injected fluid into the thief zone thus creating short-circuit to the nearby producer wells. A new autonomous outflow control device (AOCD) has been developed recently to choke the injection fluid into the propagating fractures crossing the well autonomously after reaching a designed flowrate thus maintaining a balanced/prescribed injection distribution. This work focuses on modelling design workflow to find the optimum completion design and demonstrates its added value through an extensive dynamic reservoir simulation study. Like other OCDs, this device should be installed in several zones in the injection well. The device is a bi-stable flow control device with two operating conditions, one, devices operate as normal passive OCDs initially, and two, if the injected flowrate flowing through the valve exceeds a designed limit, the device will automatically shut off. This allows the denied fluid to that specific zone to be distributed among the neighbouring zones. This performance enables the operators to minimise the impacts of thief zones on the injected fluid conformance and to react to a dynamic change in reservoirs properties specifically the growth of fractures. This also reduces the injection cost and improving the reliability of the injection well systems. A sector reservoir-model coupled with a Geomechanics model via commercial reservoir simulation software was established to study the impacts of temperature and flowrate of injection fluids on the performance of injection wells completed with various completions. The simulation study showed less imposed pressure and much more efficient fluid conformance and fracture growth was delivered with the new device compared to various other completions. The results showed how the new device may change the sequence of thermal fractures initiation and the extends of their growth. This autonomously reactive control on the injection fluid conformance resulted in an increased sweep and ultimate oil recovery (up to 20%) while reducing the total volume of injected fluid (by 30%), so significantly increased field NPV. This study illustrates how efficiently the new injection valve chokes/restricts water into dynamic thief zones in a reservoir. This new device is autonomous and reacts to the rate of fluid passing through and eliminates the cost of alternative techniques including running PLT and following intervention actions.