The fluid salinity in a geothermal field is important element in designing a project; production and injection wellbores, plant thermodynamic processes, and generation capacity. The high-temperature, high-salinity fluid at the Salton Sea Geothermal Field (SSGF) SSGF has interesting characteristics that could be used to estimate zonal contribution from wells with two or more producing intervals. In the Salton Sea Geothermal Field (SSGF) it is paramount to develop cost effective well clean-out procedures on the injecting and for the producing wells to remove scale. This in turn can be used in estimating zonal contributions and likely zones of wellbore scaling. Production measurements using orifice meters at the SSGF can have a large error factor due to the nature of two-phase flow utilizing empirical flow equations and hostile thermo-chemical conditions. This paper describes a correction process that removes noise from the raw production field data, allowing detection of more subtle production, wellhead deliverability, and salinity trends. The field production measurements were corrected using a mass-energy balance (MEB) model of the plant process thermodynamics, subtle variations in wellhead salinity were noted in two wells with one deep production interval and shallower production. The well with only one deep fluid entry showed little or no daily variation in wellhead salinity. This corrected data was used to investigate production well zonal contribution by variations in total produced wellhead salinity. This in turn can be used in estimating zonal contributions and likely zones of wellbore scaling. This concept was developed further by making some a simplifying assumptions regarding the vertical reservoir salinity profile based on a double-diffusive convection reservoir process. A linear salinity profile with depth from ~20% TDS at -4000 ft ASL and to ~31% at -8000ft ASL was assumed to investigate this hypothesis further. Thus, differing production zones depth will have different salinities. This analysis showed consistent relative zonal changes with time as wellbore scale built up in the two wells with two production zones. After each wellbore clean out cycle, changes in zonal contribution were noted. Additionally, once some estimate of zonal mass contribution is made, a corollary estimate of zonal productivity index (PI) can be made. This method has a significance in inferring productivity from each zone of the production wells which has a significance in improving the productivity of each zone by evaluating the optimum depth, type of clean outs, frequency, and efficiency of clean out jobs for producers. This information was used to evaluate and design well scale cleanouts and optimize wellfield operations and capital expenditures.

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