Generation model and drilling method of hydrothermal geothermal resources in Henan Province

Abstract:

According to the geological environments where the geothermal resources occur, hydrothermal geothermal resources in Henan Province can be classified into 3 types: subsidence or sedimentary basin, piedmont basin and mountain uplift. High heat temperature sources from convection heat transfer in deep mega geotectonics and heat conduction in intrusive rocks formed pore, fissure and karst geothermal resources through heat exchange with Neogene, Paleogene and Paleozoic shallow groundwater. During the 14th five-year Plan Period, the exploration and development of hydrothermal geothermal resources in Henan is mainly focused on karst heat storage at depth of 1800 to 4000m. This will bring a new challenge to geothermal drilling engineering. According to formation characteristics and experience, it is proposed that deep geothermal drilling should follow the general principle of “eco-friendliness, high quality and efficiency, safety and health”. In regard to formation characteristics and drilling requirements, the drilling process will be selected in the order of priority as below: first, air drilling (pneumatic DTH hammer, air-lift reverse circulation, positive air circulation core-drilling); second, drilling fluid + air (air-lift reverse circulation); and finally, drilling fluid (rotary + PDM); thus achieving the compound drilling method with multiple drilling processes in one well.

Key words:hydrothermal geothermal; drilling method; air drilling; Henan Province