Present-day geothermal regime of the Junggar Basin, northwest China: Implication for hydrocarbon distribution and geothermal resources

Abstract

The geothermal regime not only reflects the basin’s evolutionary history but also controls the formation of both fossil energy and geothermal resources. The deep geothermal characteristics of the Junggar Basin in northwestern China have remained unclear due to limited temperature data. In this study, we collected new temperature data from over 450 boreholes drilled in the past decade to investigate the geothermal gradient, heat flow, formation temperatures at depths of 5 to 10 km, and the thermal structure of lithosphere. The results show that the geothermal gradient ranges from 14.0 to 29.8℃/km, with an average of 20.7℃/km, and heat flow ranges from 32.7 and 68.5 mW/m², averaging 45.8 mW/m². Heat flow varies between uplifts and depressions, influenced by basement relief, with further regional variation in the north and south due to basement lithology and faults. The ratio of crust to mantle heat flow and the thermal lithosphere thickness across different tectonic units ranges from 0.74 to 1.92 and 150 to 270 km, respectively, confirming the basin’s stable tectonic background. Formation temperatures at 10 km depth ranges from 155℃ to 311℃, increasing from the center to the basin’s margins. These findings suggest that oil can be found at depths of 8000 m in the Central Depression, while high-temperature geothermal resources are present around 5000 m in the Eastern Uplift. This study provides a comprehensive understanding of the geothermal regime and valuable insights for future resource exploration in the Junggar Basin.