Line Mine: a Process for Mitigating Injection Well Damage at the Salton Sea, California (USA) Geothermal Field

Abstract

Injection wells that, reinject spent brine at the Salton Sea Geothermal Field can suffer damage as a result of iron silicate and heavy metal scale deposition in the wellbore and formation. A process, known as Line Mine, has recently been developed to polish brines and collect scale deposits at the surface just prior to injection. The process consists of passing brine, exhibiting a of -5.0, through a conduit packed with coiled, galvanized poultry wire for a time sufficient to precipitate a significant amount of iron silicate and heavy metal scales thereon. The wire packing serves to filter some siliceous suspended solids from the brine, while simultaneously removing and recovering a small amount of silver, copper, antimony and arsenic by a cementation reaction. Scale deposition downstream of Line Mine (in surface injection facilities and wellbores) is greatly reduced. The useful life of injection wells appears to be extended as a result of this brine-treatment process by reducing wellbore tubular scaling and reservoir formation damage.