| Abstract |
Bio-chemical and physical clogging significantly reduce efficiency and increase operational costs in geothermal systems. This work presents a thermo-hydro-chemical tool for forecasting clogging in geothermal doublet systems, spanning the reservoir, wellbores, pipelines, and surface facilities such as heat exchangers and degassers. For subsurface calculations, the tool integrates a three-dimensional (3D) reactive transport model using a finite element solver to simulate continuum-scale Darcy flow, mass, and heat transfer, with chemical reactions handled by PHREEQC. A custom interface is developed to dynamically couple the FEM solver with PHREEQC via a sequential non-iterative approach (SNIA) and to update key transport properties such as porosity and permeability. For wellbores and pipelines, the tool employs PHREEQC’s one-dimensional (1D) reactive transport model, coupled with a pipe flow model to compute frictional pressure losses and update pipeline diameters. Surface facilities are treated as zero-dimensional units connected to the pipes, where equilibrium reactions are solved based on operational parameters to simulate scale formation. Subsurface and surface domains are solved sequentially, exchanging updated flow and chemistry conditions to capture their interdependent behavior. The model is tested against field case studies from geothermal operations and shows good agreement with observed data. Results demonstrate the tool’s ability to capture complex geochemical interactions, identifies bio-chemical scale formation, and supports treatments like ionic modification and pH control to reduce costs and extend system life. |