Geothermal chemical characteristics and genetic model of the Qingshankou Formation in the Daqingzijing area, southern Songliao Basin

Abstract

Objective With high reservoir temperature, good lithology and high water content, the Qingshankou Formation is the best geothermal reservoir of Daqingzijing area, the saddle of the Changling Depression. Therefore, elucidating the genetic model of geothermal water is of great significance for the sustainable development and utilization of geothermal resources in this area. Methods In this study, the source and mixing process of geothermal water in a target area were studied by hydrochemical testing of geothermal water samples collected from 7 wells in the Qingshankou Formation, combined with 8 groups of hydrogen and oxygen isotope data, and a genetic model was established. Results The results show that the geothermal water of the Qingshankou Formation is mainly Cl-Na-type fluid, which is partially balanced. And the geothermal water is originated from the precipitation and primary sedimentary water in the Changbai Mountain area, with recharge elevation of 2 347-2 370 m. A geothermal fluid with a reservoir temperature of 81.25-112.80 ℃ was formed after the cyclic heat absorption process and was stored in the clastic rock reservoir of the Qingshankou Formation in a semi-open system. Conclusion In addition, the northeast-oriented and northwest-oriented fault systems in the study area are the main water conducting channels for geothermal fluid circulation. During the deep circulation, geothermal fluid reactions with surrounding rock minerals, resulting in the dissolution of carbonate and silicate minerals, forming geothermal water resources dominated by Na+, Cl- and HCO3- ions.

Keywords

• southern songliao basin
• daqingzijing area
• geothermal water
• hydrochemical characteristics
• genetic model
• geothermal reservoir
• clastic rock reservoir