Performance Optimization of Water Injection Wells Using Autonomous Outflow Control Device Technology in Offshore Norway

Abstract

Abstract Making good horizontal water injection wells is more challenging than making good horizontal producers, linked to the uncertainty around formation impairment (if no or limited clean-up) and the possible problem of "thief zones" that steal a major part of the injected water and deliver low sweep efficiency. Autonomous Outflow Control Devices (AOCD) can reduce the problem of "thief zones" and were piloted in a recent well in the Ivar Aasen water injector offshore Norway. To limit injection into possible thief zones (or limit the chance of making such thief zones) normal ICDs, often used for injectors as well as producers, were installed in combination with the new technology that close at a certain differential pressure or injection rate. As a dual system, this should give quite an even injection along the whole well. Completion design studies were performed in both the full dynamic reservoir model and a simpler steady-state inflow/outflow wellbore modelling pre-drill. The completion design was finalized post-drill by quickly updating the model with the actual log data from the drilled well. While tracers indicated a clean well after the initial clean-up, the well surveillance during injection logging confirmed injection along the entire completed interval of the wellbore. Also, a significant breaking point on the step-rate test (SRT) was observed which was different behaviour than what has been conventionally observed from the wells completed with non-AOCD completion. Improved water management is key for many assets such as Ivar Aasen field. The first pilot installations of AOCD technology in Norway in this field demonstrated this technology could help to make better wells and improve sweep efficiency in difficult geological formations. This again improves the environmental measures such as power usage and the need for chemicals to treat injected and produced water.