Abstract: A method for controlling fouling of a heat exchange surface exposed to a high-enthalpy geothermal brine tending to form silica scale, but containing less than a saturated amount of cations capable of reacting with sulfates. The method adds a limited amount of sulfuric acid to the brine to form a mixture. The amount of sulfuric acid is limited to that required to produce sulfates sufficient to apparently complex with silica, but less than the amount required to increased the sulfates to above saturation amounts of sulfate reacting cations, significantly reducing or virtually eliminating sulfate and silica deposits and fouling. The addition is further controlled to an amount which reduces the pH of the mixture to no less than about 4.5. The addition does not significantly increase corrosion rates of mild steel heat exchanger materials of construction.

Abstract: Wellhead flow control apparatus for controlling the flow of fluids from a well producing fluids and debris including a novel device for separating and accumulating the debris. The device comprises an outer shell defining an enclosed accumulation chamber, a perforated outlet conduit communicating with the chamber to allow the passage of fluids but prevent passage of debris, and access means to facilitate periodic removal of the accumulated debris. The wellhead apparatus is especially useful for flow control of fluids from geothermal steam wells.