Integration of Isotopic Metrics with CO2 Analyzers and Robust Modeling for Effective Reservoir Monitoring of a Field-Scale CO2 Flooding Project

CO2-EOR is a critical technique for maximizing oil extraction from reservoirs in Abu Dhabi. Evaluating sweep efficiency and identifying breakthrough times are essential for optimizing existing and future CO2 projects. This study focuses on utilizing CO2 carbon isotope composition and molar concentrations along with model calibration to monitor sweep efficiency in production wells of an Onshore field. The goal is to optimize the project by adjusting the injection and future producer well placements, leveraging the distinct isotopic signature and robust modeling techniques. CO2 is injected through specific horizontal injectors in the northern region of the field and periodic analyses of these components’ composition and isotopes in oil and water producing wells indicate the degree of breakthrough. The approach integrated all the available data from tracers, isotopes and CO2 analyzers in order to calibrate the model. CO2 is mostly flowing in the upper layer of the reservoir. An assessment of multiple options following an uncertainty analysis workflow is conducted; to tackle reservoir challenges. The approach also worked on increasing the permeability contrast in the best rock type to facilitate the gas flow in the upper layer, emulating possible fractures in the model. Findings from CO2 molar and isotope measurements in both injector and producer wells show that injected CO2 tends to breakthrough preferentially in certain regions, indicating varied reservoir quality across the field. Isotopes tend to indicate CO2 breakthrough sooner than the CO2 molar concentration, demonstrating the sensitivity of isotopic metrics in detecting changes in producer wells, a finding which has also been observed clearly in one of the four wells. Data also recommended the need to convert the existing CO2 continuous injectors into WAG as a mitigation plan to the increasing trends in breakthrough volumes. This study presents a novel approach to monitoring CO2 flood advancement in oil reservoirs by integrating isotopic, molar concentration data and model calibration. The use of a distinct isotopic signature for injected CO2 provides a cost-effective and accurate method for evaluating sweep efficiency. The methodology's ability to detect changes in producer wells and the demonstrated efficiency of CO2 WAG over continuous injection highlight the potential for optimizing EOR projects, along with offering valuable insights for future reservoir management and EOR strategies.