Hydrocarbon Wealth Management: Rejuvenation of a Brown Field through Analysis of Existing Water Injection System

Abstract

A private company acquired operatorship of a brown oil field in 2020 from a National Oil Company (NOC) of India to enhance production from the field. Due to Covid-19 outbreak, operatorship was transferred in 2021. Soon as the company took over the operation, it met with surprises in terms of a smaller number of flowing oil wells due to operational reasons. However, the most disturbing was the significantly lower field water injection rate than reported by the NOC. The company undertook pressure measurement in wells to find reasons for production non-sustainability and reduced injectivity. Based on poor analysis of pressure data, the best injection well in the largest producing reservoir was interpreted to be hydrodynamically unconnected with the up-dip producers and recommended for disconnection from injection network by subsurface team to increase water injection rate from the remaining injectors. The study team reviewed the geological model and categorically ruled out discontinuity of the sand body with its up-dip producers. The Management ordered third-party review to resolve uncertainty and suggest remedial measures to improve water injection performance. The review of historical production, injection, pressure data and movement of oil water contact with time has improved the understanding of the inter and intra reservoir pressure communications in the field. The data synthesis has confirmed sand/hydrodynamic continuity between producers and injectors. Performance review of injection wells and the Water Injection Plant (WIP) have brought out bottlenecks in the system. The poor-quality injection water and the lapses in upkeeping of WIP were the primary reasons for loss of injectivity. WIP revamping and replacement of the existing oversized micron filter with smaller size have been recommended. To ensure uninterrupted water injection, conversion of one injector to pilot dump flooder has been suggested, a first of kind in India.