Tuesday, July 14, 2026, 01:00 PM - 02:30 PM ET
Talk title: Scale Deposits from Geothermal Brines: Origin and Control
Presenter : Oleh Weres, GeoBrineLab
Time: Jul 14, 2026, from 1:00 pm to 2:30 pm. Location: Online
Abstract: Undisturbed geothermal brines exist in chemical equilibrium with the reservoir rock. Extraction from the reservoir and harvesting of heat disrupts the state of equilibrium.
Removing heat in a heat exchanger to boil an organic fluid (the “binary” process) decreases temperature causing supersaturation and possible deposits; for example, silica, barium sulfate and sulfides of antimony and arsenic.
In addition to decreasing temperature, separation of steam concentrates the brine and strips out carbon dioxide, increasing pH and causing calcium carbonate and metal silicates to precipitate, while accelerating polymerization and deposition of silica itself.
Precipitation of calcium carbonate and barium sulfate are familiar problems, hardly limited to the geothermal context, effectively controlled using proper inhibitors. The same or similar products are also effective against metal silicates. These inhibitors attach themselves to cations on the surface of a growing crystal, blocking growth.
Silica itself, while commonly confused with metal silicates, is totally different in terms of mechanism with limited possibilities for control. Colloidal particles of amorphous silica nucleate dispersed in the brine, grow, and deposit on surfaces forming deposits which are cemented by further deposition of silica between the particles. Amorphous silica contains no cations, so there is no place for conventional scale inhibitors to grab on to. They are at best indirectly effective by blocking formation of metal silicate particles which seed silica particles. Silica deposits are most often controlled by limiting temperature drop and/or acidifying the brine, oftentimes causing corrosion.
In addition to temperature, the solubility of As and Sb sulfides is controlled by hydrogen sulfide in the brine. Stripping out hydrogen sulfide when steam is separated increases the solubility of these minerals.
These processes are illustrated by modeling brine chemistry in geothermal power systems of several configurations, predicting a variety of scale deposits.
Biography : Oleh Weres has more than 50 years' experience in the geothermal power industry. Oleh holds a PhD in Physical Chemistry from the University of Chicago and was a Miller Institute fellow in chemistry at the University of California, Berkeley. His professional experience includes 14 years in the Earth Sciences Division of Lawrence Berkeley National Laboratory, 20 years as the owner of the Sonoma Research Company in Napa, CA, and 14 years in the Sales and Research and Development departments of ChemTreat. Currently he is the owner of GeoBrineLab, a consulting and contract research firm based in Reno, NV. He has researched a wide range of topics pertaining to the chemistry of the geothermal power industry, including scaling and corrosion control, silica, hydrogen sulfide emissions, arsenic and antimony sulfides, and recovery of lithium and metals from brine. In addition to his extensive laboratory experience in physical, inorganic, analytical, and electrochemistry, he has developed computer programs to model geothermal brines, condensers, water cooling, and chemical treatments. He has contributed to The Geysers, Imperial Valley, and dozens of other geothermal projects throughout North America and worldwide. He has also investigated selenium in the environment, advanced oxidation processes, corrosion in nuclear power plants, and defense applications. Oleh is a registered patent agent with the USPTO and personally holds 14 patents.
Virtual Event : The lecture will be presented online using the Teams link provided below. For additional questions, please contact Chris Boucher at CBoucher3@slb.com.
TCC Restriction: This presentation should not contain any material related to US Embargoed Countries or US Sanctions to Russia or any other country. Still, if anyone is inadvertently connected and is working with a project or people related to these groups, we ask you to not participate in this event.
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