Temperature conditions and resource assessment of low-to-medium-temperature convective geothermal systems in Jiaodong Penisula, China

Abstract

The structural units in the Jiaodong peninsula mainly consist of the Jiaobei uplift, the Jiaolai basin and the Weihai uplift. The heat flow in the Jiaodong peninsula, based on silica temperature, shows that the Jiaobei uplift and the Weihai uplift areas have higher heat flow than the Jiaolai depression basin, and that the closer you get to the centre of the axis of the uplift area, the higher the heat flow becomes. The lithology of the uplift area is mainly composed of intrusive and metamorphic rocks with high thermal conductivity and permeability, while the lithology of the depression basin is dominated by sandstone with low thermal conductivity and low permeability. Therefore, the bottom of the Jiaolai basin acts like an insulating cap or roof, both for heat and water flow, which causes the heat flow pattern to be different in different structural units. In order to visualize the heat flow distribution more clearly, a 3D temperature model of the Weihai uplift area has been constructed using Leapfrog. In addition to the Wenquan fault having a higher temperature, the fault is the main structure controlling the hot spring and heat flow distribution in this area. A lumped parameter model was used to simulate the water level response to variable production in the Yujia Tang geothermal field. The results show that if the production is increased to about 15 times the current production, the water level will drop by 180 m, which should still be manageable. The volumetric method was used to estimate the geothermal production potential of the Wenquan Tang and Dong Tang geothermal fields, showing that the thermal energy production potential of these two areas is more than 2-3 MWth each (P90 estimate).