Abstract
Integrating lithium extraction with geothermal operations has the potential to significantly improve the economic performance of geothermal developments by coupling heat production with critical mineral recovery. However, major uncertainties persist regarding how highly saline brines influence the tightly coupled thermal, hydrological, and geochemical processes that govern reservoir behavior, mineral scaling, and corrosion. These challenges are amplified in high‑TDS systems, where rapid shifts in temperature and fluid composition can accelerate permeability reduction, injectivity loss, and overall decline in well performance.
This study investigates these risks within the Smackover Formation of northern Louisiana through reactive transport modeling designed to quantify mineral scaling, dissolution, and the evolution of geochemical conditions during five years of geothermal doublet operation. The modeling framework incorporates Pitzer‑based thermodynamics, temperature‑dependent reaction kinetics, and coupled fluid flow, heat transport, and geochemical reactions. Key reactive mineral phases—including calcite, dolomite, anhydrite, feldspar, silicates, and corrosion‑related iron minerals—are evaluated for their impacts on permeability changes near production and injection wells.
Model results show that mineralogical evolution is highly sensitive to temperature gradients, flow conditions, and saturation states in hypersaline environments. Coupled heat‑flow simulations also predict the development and migration of the thermal plume. Overall, this work provides a mechanistic framework for assessing geochemical and thermal risks in geothermal–lithium co‑production systems. The findings support long‑term operational planning and underscore the importance of incorporating fully coupled THC processes when forecasting scaling, flow impairment, and system performance in high‑salinity formations such as the Smackover.
Bio
Dr. Ram Kumar is a staff scientist in the Geothermal Energy & Subsurface Systems group at Idaho National Laboratory, USA. With over 10 years of experience in thermal-hydrological-chemical (THC) modeling, his expertise extends to geologic hydrogen production, reservoir thermal energy storage (RTES), enhanced geothermal systems (EGS), geological carbon sequestration (GCS), lithium characterization in geothermal brine, and the assessment of critical and rare earth elements (REEs) in host rocks. Dr. Kumar received his Ph.D. in Chemical Engineering from the University of South Florida in Tampa, FL, and his Bachelor of Technology (B.Tech.) from the Institute of Chemical Technology in Mumbai, India. His doctoral dissertation focused on reactive transport modeling of geological carbon storage in saline formations. Prior to joining INL, he spent over three years as a postdoctoral researcher at Lawrence Berkeley National Laboratory, where he worked on computational geochemistry and the development of models to couple geochemical processes with transport in porous media for subsurface energy storage applications and the recovery of geologic hydrogen and critical minerals.