Best Practice to Establish a Reservoir Management Guideline and Operating Strategy Envelope for Improved Water Injection Strategy and Production Sustainability Assurance in a Continuous Reservoir

Abstract

Reservoir management of a developed oil field with the goal of fulfilling field development requirements and objectives is a continuous challenging process. Over time, the production and injection control, along with pressure maintenance strategies, are refined to achieve not only maximum recovery but also the most capital-efficient field development. A reservoir sectorization philosophy, by dissecting the reservoir into smaller reservoir management subareas, is commonly adopted for a large oil field. The high granularity sectorization scheme is often preferred to achieve a harmonized recovery across the field. However, a high sectorization number in a relatively continuous and noncompartmentalized reservoir can lead to some surveillance and data allocation challenges when wells are crossing multiple sector boundaries. With these challenges, we established two key aspects of reservoir management: first is to assess a potentially lower number of sectorization, and second is to generate a well level production and injection guideline. These guidelines must fulfill both short-term production sustainability assurance and long-term field development requirements and objectives. In this paper we present an integrated workflow to establish a reservoir management guideline. We started by an analytical evaluation of the historical reservoir management and waterflooding practices. The identified area(s) of improvement from the analytical evaluation were incorporated into dynamic models for different sectorization schemes. The simulation outputs were thoroughly analyzed by a standardized criteria matrix where several parameters were cross referenced to select the optimal sectorization scheme to achieve an even pressure depletion, harmonized sweep, absence of water-cut disparity along with strong economic indicators. A data analytic process on a large pool of historical well production tests and a historical surveillance database was performed to derive different well-level production and injection constraints. Subsequently, output results from sensitivity analysis were evaluated to finalize a robust new operating guideline. In this paper we will highlight some lessons learned from a case study where a lower number of reservoir management sectors also provided a substantial added value. The benefits are more apparent with implementation of new well-level guidelines where well-level production, injection, artificial lift, and pressure guidelines are recommended for operational considerations. The workflow to establish or to revise a reservoir management strategy from this study helped to lay out the critical foundation for all the stakeholders involved in asset management. The reservoir management practice presented in this paper is useful to make informed decisions so that well-rounded recommendations are available for production sustainability assurance and long-term field production performance optimization. Other fields may also benefit from the reservoir management concepts and workflows presented in this paper.