Evaluation Of Geothermal Reservoir In Xiongan New Area

The establishment of the Xiongan New Area is a"grand project of the millennium and a major national event"and has great demonstration significance.The exploitation and utilization of Xiongan geothermal resources will add new economic vitality to the Beijing-Tianjin-Hebei region.In this paper,based on the information revealed by hydrogeological survey,hydrochemical analysis and borehole,combined with geophysical and logging data,the seismic working area was established,61 survey lines were interpreted,and the structural depth maps of the top,bottom and bottom of Wumishan Formations as well as the residual thickness distribution maps of Wumishan Formations and Gaoguozhuang Formations were compiled.The paper mainly obtains the following research conclusions and results:Xiongan New Area is located in the Sino-Korean quasi-platform(Ⅰlevel),the North China fault depression(Fa level)and the Jizhong depression(Tuo level).The area is divided across the Rongcheng uplift,Niutuozhen uplift and Gaoyang low uplift,which are three grade grade tectonic units.(1)The geothermal source sites are mainly sedimentary basin,the characteristics of the main factors are:deposition,structure,heat source,water source of the hydrodynamic conditions,such as the heat source,water hydrodynamic conditions factors laid the foundation of geothermal resources in this area,sedimentary and structural factors determine this area geothermal heat reservoir and caprock,hot water channel distribution space form and physical property characteristics.(2)The residual thickness of the Wumishan Formation in the study area varies from 700 m to 1400m,with large residual thickness in the south and thin residual thickness in the north.In Xiongxian County,due to the fault failure of Niudong Fault,the eastern area is thin near the fault and gradually thickens towards the west.The residual thickness in the southwest reaches 1400m.In the Rongcheng area,the residual thickness is small in the east and large in the west.In the east,the residual thickness is affected by the failure of the Rongdong fault,and the local thickness becomes smaller.(3)According to its occurrence conditions,geothermal water in Xiongan New Area can be divided into two types:one is pore water occurring in clastic sedimentary layers,and the other is bedrock fissure water occurring in dissolution and fissure of carbonate rocks.The geothermal water type is Cl·HCO3-Na type water.(4)The heat flow value of Niutuozhen Uplift in the study area is 80.61-113.8m W/m~2,the heat flow value of Rongcheng Uplift is 54.01-70.69m W/m~2,and the heat flow value of Gaoyang Low Uplift is 45-71.6m W/m~2,obviously higher than the average heat flow value of 61m W/m~2 in China.The geothermal gradient of the cap is generally high in the north and low in the south,high in the middle and low on both sides.The geothermal gradient of the central cap in Xiongxian County is high,reaching 6.0℃/100m locally,and the geothermal gradient of the new cap is basically above 3.0℃/100m,which belongs to the abnormal area of geothermal gradient.For Xiongan New Area,we summarized a set of methods for evaluating geothermal reservoirs by using seismic data interpretation.This method can be used as a reference for evaluating geothermal reservoirs in other areas.