Abstract
The interaction of CO2-rich water with olivine was studied using geochemical reaction modelling in order to gain insight into the effects of temperature, acid supply (CO2) and extent of reaction on the secondary mineralogy, water chemistry and mass transfer. Olivine (Fo93) was dissolved at 150 and 250ºC and pCO2 of 2 and 20 bar in a closed system and an open system with secondary minerals allowed to precipitate. The progressive water–rock interaction resulted in increased solution pH, with gradual carbonate formation starting at pH 5 and various Mg-OH and Mg-Si minerals becoming dominant at pH>8. The major factor determining olivine alteration is the pH of the water. In turn, the pH value is determined by acid supply, reaction progress and temperature.
Highlights
CARBONATE mineral scaling is commonly associated with geothermal fluid utilization, both in the reservoir as well as in production and reinjection wells and surface pipelines (Gunnlaugsson 2012; Gunnlaugsson et al, 2014)
The interaction of CO2-rich water with olivine was studied using geochemical reaction modelling in order to gain insight into the effects of temperature, acid supply (CO2) and extent of reaction on the secondary mineralogy, water chemistry and mass transfer
The progressive water–rock interaction resulted in increased solution pH, with gradual carbonate formation starting at pH 5 and various Mg-OH and Mg-Si minerals becoming dominant at pH>8
Summary
CARBONATE mineral scaling is commonly associated with geothermal fluid utilization, both in the reservoir as well as in production and reinjection wells and surface pipelines (Gunnlaugsson 2012; Gunnlaugsson et al, 2014). Olivine is a major constituent of mafic rocks and commonly associated with geothermal systems. It contains a limited number of main elements (Mg, Fe2+, Si and O) and may serve as a suitable system to demonstrate and test geochemical reaction modelling with observations from experiments. A number of studies have focused on CO2ÀwaterÀrock interaction by geochemical modelling and laboratory experiments. Under geothermal conditions these include, for example, forsterite dissolution and magnesite formation (Giammar et al, 2005) and CO2– water–basalt interaction (Gysi and Stefansson, 2011, 2012a,b,c; Galeczka et al, 2014).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
