Integrated Workflow for Designing a Multi-Zonal Water Injector with Intelligent Well Completion Functionality

Abstract An injector well that maintains flow conformance and integrity across the well lifecycle requires detailed planning of downhole completions. Use of Outflow (Inflow) Control Devices (ICDs) and Inflow control valves (ICVs) provide the flexibility and control over injector well performance. This paper presents a reservoir-centric integrated workflow applied to a 6-zone injector well to optimally design the ICD nozzles count and ICV choke settings for achieving target injection rates across each zone and pressure differential balance over ICD and ICVs over the well lifecycle. The deepwater injector well in this study crosses multiple zones with shale breaks in between. The lower completion is therefore designed with both passive (ICDs) and active flow control (ICVs) devices to optimize injection conformance across the multiple zones. Understanding the water injection, reservoir depletion strategy and expected injector well behavior was critical in the design process. A pseudo steady-state well model was coupled to the field scale reservoir simulation model to predict the injection rate for each zone over the well lifecycle to achieve maximum sweep efficiency with the zonal rate conformance. The completion design philosophy aimed to control the pressure drop across the ICDs and ICVs under critical limit of erosion while maintaining flow conformance across all zones. 100s of simulation cases were run to optimize the completion design over the 6-zone interval with one ICV and multiple ICDs across each zone. Due to the high density of small sub-seismic scale faults, one of the key uncertainties in the field was the presence of throw and cross-fault communication and connectivity between wells for each zone. Horizontal producer and injector wells help in maximizing the reservoir contact across multiple fault blocks which on the other hand causes a threat of water breakthrough in producers and challenges managing efficient sweep across the multiple zones via the injectors. Designing the multizone intelligent well completion (IWC) to control flow for injector provided flexibility to achieve optimal water injection. Due to the permeability contrast in the reservoir, selective zones had more capacity for injection fluid causing imbalance of conformance. Controlling the choke position on ICVs and selective plugging of nozzles in ICDs enabled well design to reach target injection rates in each zone. Additionally, by sensitivity analysis the well completions were optimized to minimize erosional damage and therefore increase the expected life of the well. Uncertainty analysis provided framework to tune the completion design post-drilling for contingency scenarios of missing zonal coverage by the well. The integrated workflow of optimizing the completion design for an IWC to achieve conformance while maximizing the well injection over the life of the well becomes an enabler for the future deployment of IWCs. The example presents robust design blueprint for such multi-zonal injection IWCs