Geothermal energy potential analysis of karst reservoir in Linqing depression of Shandong Province

There are thick carbonate strata of Cambrian-Ordovician buried at Linqing depression in Shandong Province, which are a favorable target for geothermal exploitation. Based on the seismic interpretation and drilling results obtained during petroleum exploration, and by comprehensively analyzing the results of previous studies, the authors compiled the average geothermal gradient map of Cenozoic and the contour map of Ordovician burying depth, and adopted temperature gradient estimation formula for the strata temperature calculation of Ordovician roof. Combined with the Cambrian-Ordovician strata thickness distribution, and using the temperature of 120 ℃ at the Ordovician roof as the beginning temperature and 90 ℃ as the lowest temperature, the authors predicted the prospect of geothermal power generation. The results show that the geothermal resources in the karst reservoir are really prospective, and the total heat resource that can be used for geothermal power plant is 1.27×10¹⁵ MJ, which is equivalent to 1.35×10⁵ MW of electricity power. And the heat resource contained in the 240 ℃ high temperature area can meet the requirements of power supply in this region.