Advanced and Automated Diagnostic Plot Techniques for Enhanced Reservoir Surveillance and Efficient Management of Extensive Coal Bed Methane Fields

Abstract Managing Coal Bed Methane (CBM) fields with numerous production wells presents both challenges and opportunities for applying advanced diagnostic plots. This paper discusses the application of these techniques in reservoir surveillance of large-scale coal gas reservoir Sohagpur field with approximately 400 wells featuring diverse completions. Diagnostic plots are employed to analyze well performance, reservoir conditions, and flow dynamics, tracking pressure changes to ensure optimal dewatering and gas production. The study introduces a novel methodology utilizing advanced diagnostic plots tailored to the flow characteristics of coal reservoirs, addressing desorption, non-static permeability, and two-phase flow. The diagnostic plots include History Plot, Reservoir Diagnostic Plot, Pseudo-isotherm Plot, and Auxiliary Diagnostic Plot. Production is monitored at the field level through classical After-Before- Compare (ABC) plots to evaluate well conditions. Well-level diagnostic plots facilitate understanding of depletion states and estimated ultimate recovery (EUR), while infill-surrounding plots assess interference effects. These methodologies provide comprehensive analysis of well performance, gas desorption behaviour, and flow dynamics. Additionally, these plots are automated and made interactive using digital solutions. The array of diagnostic tools utilized in the Sohagpur CBM field has generated substantial insights into the performance patterns of various wells. The use of ABC plots facilitates the swift identification of wells encountering issues, enabling timely and effective intervention measures. Furthermore, advanced diagnostic plots, including Inflow Performance Relationship (IPR) plots and Normalized Rate plots against Cumulative Production, optimize drawdown strategies and provide insights into EUR. Infill-surrounding plots play a crucial role in monitoring interference among wells and tracking production behaviour changes due to infill drilling practices. The Pseudo-isotherm plot offers a novel method to correct lab isotherm data in accordance with the material balance of a flowing CBM field. Collectively, these methodologies and the automated dashboard enable real-time decision-making to optimize field development strategies, ensuring sustained gas production, efficient resource recovery, and minimized downtime.