Present Geothermal Fields of the Chagan Depression in the Yingen-Ejinaqi Basin, Inner Mongolia, Central China
Yinhui ZUO, Shu JIANG, Qingqing HAO, Yongshui ZHOU
[Chengdu University of Technology, China]
The study of geothermal fields in a basin is significant for the evaluation of petroleum and geothermal resources, and can also provide insights for basin dynamics and tectonic-thermal evolution. This work tests rock thermal conductivity of the Cretaceous Chagan Depression in the Inner Mongolia, central China. The geothermal gradient of four wells is calculated and four terrestrial heat flow data are generated for the first time in the Yingen-Ejinaqi Basin. The results show that the rock thermal conductivity of the Bayingebi 1 and 2 Formations is high, with an average value of 2.38 and 2.33 W/m·K, respectively. The Suhongtu 1 and 2 Formations contain certain magmatic rocks, and the thermal conductivity of magmatic rocks is relatively low. As a result, their thermal conductivity is relatively low, with an average value of 1.78 and 2.21 W/m·K, respectively. The Yingen Formation has a shallow burial depth, with loose rocks and large porosity, and the rock thermal conductivity is relatively low as only 1.85 W/m·K. A total of 193 systematic steady-state temperature measurement data were obtained for the wells X2, X5, Y5 and Y7. The Cenozoic strata are affected by solar radiation, groundwater disturbance and other factors, which are not considered in the calculation. The relationship between temperature and depth indicates that it can be divided into three intervals, and the average geothermal gradients from the upper section to the lower section are 28.9, 37.6 and 27.6 °C/km, respectively. The terrestrial heat flow of the four wells was also calculated by the thermal resistance method with the rock thermal conductivity and geothermal gradient data. The terrestrial heat flow of the Wuliji fault nose structural belt ranges between 61.0 and 81.0 mW/m2, with an average value of 70.9 mW/m2, and that of the central uplift belt ranges from 65.1 to 69.2 mW/m2, with an average value of 67.6 mW/m2. The average terrestrial heat flow of the Chagan Depression is 70.6 mW/m2, which is higher than that of the global continent (averaged at 63 mW/m2), indicating a high geothermal background in the Chagan Depression.
|        Topic: Geology||Paper Number: 12160|