Journal article
Hydrogeochemical Evolution and Water–Rock Interaction in Thermal Groundwater of the Ili Basin, Kazakhstan: Implications for Geothermal Systems
- Research Center for Applied Hydrogeology; Department of Hydrogeology, Engineering and Petroleum Geology; Institute of Geology and Oil and Gas Business named after K. Turysov, Satbayev University, Almaty, Kazakhstan
- Vocational School of Technical Sciences, Isparta University of Applied Sciences, Isparta, Türkiye
- Geoterm Production Company LLP, Almaty, Kazakhstan
https://doi.org/10.30919/ee2637
Highlights
- Seven thermal-water wells, western Almaty sector of the left-bank Ili Basin.
- Total dissolved solids: 0.7–45.5 g/L.
- Outlet or wellhead temperature: about 42–56 °C; tested temperature at depth: 63–71 °C.
- Highest salinity at about 1,840 m; water of 0.7 g/L in a Neogene interval at about 2,018–2,202 m.
- Quartz geothermometer temperatures: about 71–82 °C.
Keywords
- thermal groundwater
- hydrogeochemistry
- water–rock interaction
- geothermometry
- Ili Basin
- Kazakhstan
Summary
Thermal groundwater in sedimentary basins is often taken to grow hotter and saltier with depth. Aisulu Kalitova, Dulat Kalitov and colleagues from Satbayev University, Isparta University of Applied Sciences and Geoterm Production Company tested this on seven thermal-water wells in the western Almaty sector of the left-bank Ili Basin in south-eastern Kazakhstan, the basin that also holds the hotter Zharkunak waters further east. They combined quality-screened chemical records with hydrostratigraphic and structural data, ion ratios, chloride–bromine relations, cation-exchange indicators, PHREEQC mineral-saturation modelling and silica geothermometers.
The water ranges from 0.7 to 45.5 g/L of total dissolved solids. Outlet or wellhead temperatures are mostly about 42–56 °C, and tests in the wells measured 63–71 °C. Water types range from dilute SO₄–Na and SO₄–Cl–HCO₃–Na water to Cl–Na–Ca, mixed Cl–SO₄–Na–Ca and a strongly saline Cl–Na water. Mineralisation does not increase steadily with the depth of the producing interval: the saltiest water comes from about 1,840 m, while a deeper Neogene interval at about 2,018–2,202 m holds water of only 0.7 g/L.
Ion and halide relations point to several sources of dissolved salts: saline formation water, reactions with sulphate minerals, cation exchange, dilution and, locally, mixing. Well 1980 is strongly supersaturated with carbonate minerals, while well 5-T is close to equilibrium with gypsum and anhydrite. Chalcedony geothermometers for wells 1/78 and 1980 give temperatures close to those measured, and quartz geothermometers about 71–82 °C. The authors describe the western Ili system as a set of separate compartments with their own water–rock histories rather than one sequence controlled by depth, and see this as a basis for reading the chemistry of low- to moderate-temperature sedimentary geothermal systems.
How to cite
Aisulu Kalitova, Vyachaslav Zavaley, Dulat Kalitov, Yergali Auyelkhan, Balnur Kismelyeva, Meruyert Kaygusuz, Murat Kalitov and Zaure Atabekova (2026). Hydrogeochemical Evolution and Water–Rock Interaction in Thermal Groundwater of the Ili Basin, Kazakhstan: Implications for Geothermal Systems. ES Energy & Environment (accepted manuscript, published online 31 October 2026). https://doi.org/10.30919/ee2637