Effective Reuse of the Produced Water - A Case Study from a Field in South Oman

Produced water is an inextricable part of the hydrocarbon recovery processes, yet it is by far the largest volume waste stream associated with hydrocarbon recovery. In a C-field in South Oman, the produced water has been disposed in the aquifer zone of the producing formation. The feasibility of alternative ways to dispose water at surface using alternative options is being evaluated with the objective of reducing (or completely stopping) this water disposal which has shown benefits in maximizing the recovery by reversing the pressure decline. A simple model has been used to quantify the benefits of produced water re-injection into the deep aquifer zone. Deep water disposal (DWD) has been on-going for over 20 years in the aquifer zone in the B-formation in this field in South Oman. All the produced water from the surrounding fields is sent for disposal near the field via the C-Field Processing Station DWD system. This DWD activity has provided important energy to the system as evident in the reversing reservoir pressure trend in field. However, due to various reasons, efforts are being put forward with the aim of replacing DWD with alternative ways of disposing produced water at surface. An integrated model has been built and calibrated to the field response and used to predict the field performance. The calibrated model recommends to continue pressure to the field through water disposal or injection system. The study predicts the complete discontinuation of DWD will put significant reserves at risk eroding the field value and has quantified the amount of water available for the alternative options for surface disposal. The study has also identified an opportunity to further optimize the solution for pressure maintenance and thereby, potentially improving the recovery from the field.