Middle East Giant Carbonate Field: Integrated Water Injection Optimization Workflow

Abstract

A proper reservoir management is mandatory to optimize the water injection strategy through time, since the injected fluids tend to flush the same preferential paths, leading to a significant reduction of the incremental swept oil. This paper shows the results of an integrated workflow applied to a giant brown field with complex geology. The proposed workflow is based on a semi-automated process to optimize water injection, embodying the improvement and assessment of the 3D model. An integrated Production Data Analysis (iPDA), initially available, allowed to understand the main fluid dynamics of the reservoir, which were integrated in the 3D model since the earliest setup. Streamlines methodology was then used to compare the 3D model with the iPDA outputs in terms of subsurface dynamics, guiding the reservoir model history match process. Finally, streamlines traced on the validated model allowed to optimize water injection strategy for the forecast simulations using a semi-automatic process. It relies upon an iterative loop of rates redistribution among all active injectors, based on their own oil displacement efficiency calculated using dedicated software. The mentioned workflow was applied on Beta formation of Alpha field, which is a mid-Cenomanian carbonate giant oilfield in the Middle East region with more than sixty years of production and about five hundred drilled wells, characterized by karstic behavior. In this very challenging context, streamlines simulation technique, mostly used during the HM phase, resulted in an increase of 3D model reliability and representativeness of the main evidence from iPDA. This led to generate more robust forecast scenarios. In particular, the proposed workflow allowed to optimize the water injection strategy, adequately redistributing the overall available injection rate between all the injectors, promoting the most efficient ones, and reducing the inefficient. This approach resulted in a definitively appreciable oil reserves potential gain, consisting in the plateau extension of about one year from the forecast 3D simulations. The economic value of this result can be better appreciated if we consider that it is associated only to the re-distribution of the injection rate, without any additional capex.