Classification Of Geothermal Field And Geothermal Geology Characteristics In Nanyang Basin

Based on the data of pumping experiment on geothermal well in the basin, and combined with data of previous oil wells and water wells, the geological and hydrological characteristics of Nanyang Basin and groundwater recharge, runoff and discharge rules in this region are researched. The geothermal field types and geothermal geological characteristics of Nanyang Basin are summarized, which provides scientific basis for the development and utilization of geothermal resources in Nayang Basin. Main results about experiment research are as follows. (1)The temperature of geothermal layer of sedimentary basin increases as the depth increases, and geothermal gradient is relatively high (the average is 3.82℃/100m). It belongs to conductive low temperature geothermal system, geothermal reservoir type is multilayer.(2)The geothermal gradient and change rule of geothermal temperature are researched. On a surface and in the same depth, geothermal temperature is high where structural site is high, low where structural site low. On vertical direction, layer temperature and depth show a direct proportion relationship, geothermal temperature increases as the depth increases. The increase comes to maximum where geothermal gradient is 1500m, then decreases. The main factors that control geothermal fields are geological structure, lithology, cap rocks, hydrogeology and hydrocarbon accumulation. (3)According to the characteristics of quantity, quality and temperature of water, geothermal gradient and reservoir cap rocks, the geothermy of Nanyang Basin can be generally classified into three kinds: shallow, deep and bottom geothermal resources,Summarizes geothermal geological characteristics.The formation mechanism of geothermal fields is researched. They are mainly high-temperature bottom,good fracture corridor and water heat-resist conditions.(4)Geothermal water reserves are calculated, and exploitation potentiality is evaluated. According to the data of some geothermal wells in Nayang city, the temperature of deep thermal reservoir source (68～98℃) is drawn using the calculation of K/Mg temperature scale and geothermal gradient scale. According to thermal reservoir method, the geothermal resource reserve and fluid resource are calculated, the Neogene Shangsizu Formation are 9.37×10¹⁸J/1.41×10¹⁷J, the Paleogene are 2.73×10²⁰J/4.36×10²⁰J and bottom alabaster 9.43×10¹⁶J/4.36×10²⁰J, respectively.