Water Injection in Complex Geology: A Case Study of a Field in the Niger Delta

Abstract

Abstract Water injection is a secondary recovery mechanism often initiated when the primary drive of a reservoir / field is not enough to maintain pressure. Injected Water supports the pressure of the reservoir through voidage replacement, which in the process stimulates production by displacing oil from the reservoir towards the well. Apart from the objective of maintaining pressure and enhancing production, water injection can also be employed as a means of produced water disposal. However, most water injection projects fail on account of poor reservoir conceptualization in the modeling process, the skill of the evaluator, complex geology leading to poor sweep efficiency, water compatibility problems leading to scaling and failure of surface equipment. This paper showcases how a water injection project failed due to poor understanding of the reservoir / field geology, the lessons learnt and what was done differently to successfully conceptualize and execute another water injection project in the same field. To understand the reason why the water injection project failed, attributes were extracted, a conceptual static model was developed, and pressure plots were made, which allude to stratigraphic compartmentalization and poor positioning of the injector as the main culprit. Three (3) scenarios were tested, considering the geologic complexity of the reservoir. Scenario 3 shows a recovery factor of 48.1% and a recoverable volume of about 25.4MMSTB and was adjudged the best development scenario for the reservoir.