Integrated research & development for advancing EGS commercialization - Tipping the scales

Fundamental to successful commercial scale enhanced geothermal systems (EGS) operations is the ability to maintain both fluid temperatures and flow rates at sufficiently high levels and durations to provide a return on investment. The persistence of such operational conditions will be required for many years to decades. Confidence in long term EGS performance is not yet sufficient to justify the level of private capital investment required for widespread commercialization. While a number of technical and non-technical barriers exist, we believe that a fundamental obstacle to establishing confidence is the lack of data associated with long-term thermal-flow performance of EGS. Data collected from long-term circulation tests are needed to validate model predictions and reduce uncertainties in predicted economic outcomes. Without these well-validated predictive modeling tools, long-term reservoir management will be fraught with uncertainties and this will hinder capital investment in EGS. Therefore, we postulate that understanding long term EGS reservoir performance and evolution requires datasets, initially from experimental demonstrations but ultimately from commercial-scale EGS sites, and validated modeling suites. We note here that similar tools and techniques, proposed herein, have become invaluable in the petroleum industry where dynamic reservoir characterization is used in the long-term management and optimization of oil and gas recovery. Techno-economic analyses have also been performed for EGS but owing to the dearth of available long-term performance data, their validity has not yet been demonstrated. In this paper, we discuss the potential for carefully scaled intermediate-scale field experiments that can serve as a time and cost-effective step toward building the necessary technical basis for validating predictive modeling tools. It is widely accepted that integration of laboratory, intermediate-scale, and field-scale efforts can be an important framework for lowering overall R&D costs, accelerating technology development timelines, reducing risks, and ultimately achieving the goal of commercializing EGS. We show here that an important step in developing those linkages lies in fundamental physical and dimensional analysis, and that with careful implementation seemingly intractable challenges of decoupling phenomena can be overcome.