MSc presentation by Pham Dieu Linh

16 June 2019

Pham Dieu Linh, MSc Fellow in Chemistry of Thermal Fluids at University of Iceland will give a presentation on her MSc project on Tuesday 18 June, 2019 at 11:00 at University of Iceland, in the Faculty and Institute Lecture room on the 3rd floor.

The title of the project is:

Geochemical characterization of thermal water from Central Vietnam and Borgarfjörður W-Iceland

Linh's supervisors:

Andri Stefánsson, University of Iceland and Finnbogi Óskarsson, chemist at ISOR.

The external examiner will be Halldór Ármannsson, Chief Geochemist at ISOR.

Everyone's welcome to attend.


The geochemistry of low-temperature geothermal water in Central Vietnam and Borgarfjörður (W-Iceland) was studied as well as its potential utilization possibilities.

Twenty samples of geothermal water were collected in Central Vietnam and twelve samples in Borgarfjörður in the summer of 2018. The water temperature, pH, DIC and H2S concentrations were measured on site and major elemental composition analysed using ICP-OES and IC at the University of Iceland. Stable isotopes of hydrogen and oxygen (δD and δ18O) were also determined at the University of Iceland, by IRMS. The surface temperatures of the geothermal waters in Vietnam were 42- 96°C and in Borgarfjörður they were 40-98°C.

The stable water isotopes, Cl and B content were used to assess the water origin, mixing and water-rock interaction. Based on this analysis is was concluded that geothermal waters in Vietnam and Borgarfjörður are of meteoric origin affected by rock leaching and mixing with non-thermal water and with possible seawater or salt evaporaties in the case of geothermal water in Vietnam.

The SiO2 concentrations of the geothermal fluids in Vietnam and Borgarfjörður were 38-138 ppm and 54-178 ppm, respectively. Using these concentrations and assuming equilibrium with chalcedony the reservoir geothermal temperatures in Vietnam and Borgarfjörður were found to be as high as ~120°C and ~135°, respectively. The geographical projection of the major elemental concentrations and geothermometry temperatures revealed three geothermal anomalies in Vietnam: Le Thuy, Quang Binh; Mo Duc, Quang Ngai; Hoi Van, Quang Binh and highest temperatures at Hægindi in Borgarfjörður.

Following the utilization of low-temperature waters in Borgarfjörður and elsewhere in Iceland, the Líndal diagram suggest several utilization possibilities for the geothermal reservoirs in Vietnam including house heating and cooling, greenhouse farming, fish farming, swimming pools and bathing, drying and food processing, and even electricity production for the waters with highest temperatures. The utilization options will, however, largely depend on accessibility and the quantity of geothermal water for each location.