We present a novel, data-driven approach to integrated well/reservoir performance analysis and opportunity identification for mid- to late-life pattern waterfloods.
The Salym group of oilfields is located onshore in Western Siberia, Russia's prime oil producing province, and is operated by Salym Petroleum Development (SPD), a 50-50 joint venture between Shell and Gazprom Neft. The main productive formation, comprising strongly layered, deltaic/fluviatile sandstones, has been developed as a pattern waterflood, with over 950 deviated wells drilled since 2004. Overall watercut is currently around 82% and with oil production declining at 6-7% year on year, waterflood management is an absolute strategic priority.
The operator has responded to this challenge by investing heavily in waterflood management and performance evaluation. Particularly, a dedicated effort was made to develop the company's enterprise information architecture and create a purpose-built online waterflood management tool (WMT). All Salym geological, completion, production and well status data is automatically quality-checked, stored and updated in an integrated waterflood database and made accessible through the WMT. The WMT provides a wide range of functionality for data visualization, performance diagnostics and analysis. Furthermore, it is coupled to a full-field surveillance simulation model, which auto-updates with new oilfield data as it becomes available and outputs streamlines, well allocation factors, maps of remaining oil distribution and pattern- and block-level calculated properties.
These technologies have enabled the development and implementation of a structured methodology for waterflood performance evaluation that involves systematic assessment of blocks of 20-50 wells in the form of an Annual Field Review (AFR) followed by a series of deep-dive Integrated Block Reviews (IBRs). During the AFR, each block is assessed against a set of KPIs and scored and prioritised in terms of its health status and projected recovery shortfall. Based on this prioritisation, blocks are scheduled for review in an IBR during the course of the year. The IBRs focus on individual wells, patterns and reservoirs and during the reviews concrete well, reservoir and facilities management (WRFM) opportunities are identified to address performance gaps and sweep or accelerate remaining oil. These opportunities are captured in an online opportunity register coupled to an online database for workover strategy preparation.
The framework of technologies and processes presented in this paper was instrumental in planning and executing over 260 WRFM activities (not including simple pump change-outs) across the Salym fields in 2014, delivering in excess of 3.2 Mln bbls of in-year oil production.