Study On The Geothermal Field And The Influence Of Geological Gactors On Geothermal Development In Neihuang Uplift,Northern Henan Province

Northern Henan has a high geothermal background and good development prospects.However,most of the geothermal research in Northern Henan focuses on the Ordovician thermal reservoir in Dongpu sag,and few on Neihuang uplift.The analysis of geothermal field background,main controlling factors of geothermal anomaly and formation of geothermal field is insufficient.In this paper,the geothermal field background of Neihuang uplift is analyzed from the plane and vertical by collecting the geothermal flow data and the measured geothermal gradient data.Combined with the regional tectonic background and groundwater chemical characteristics,the main controlling factors of geothermal anomaly and the genesis of geothermal field in Neihuang uplift are studied.In addition,according to the main controlling factors of regional geothermal anomaly,the formation model is established by COMSOL multiphysics software to explore the influence of geological factors on the temperature of thermal storage and reinjection water in the process of recharge and drainage.The distribution of geothermal field in Northern Henan is in line with the distribution characteristics of North China Plain,and it is banded.The specific performance is that the background of geothermal field in uplift area is higher than that in depression area,and the main reservoirs are Neogene sandstone heat reservoir and Ordovician Karst heat reservoir.On the whole,the temperature of Guantao formation is higher than that of Minghuazhen Formation,and its water production is lower than that of Minghuazhen Formation.The upper Guantao formation is the main reservoir of Guantao formation.Fengfeng formation is the main reservoir of Ordovician Karst heat reservoir.The geothermal anomaly in Neihuang uplift is related to deep heat source,base fluctuation,structural depth,fault zone,lithologic association and groundwater.From the perspective of structural pattern,Neihuang uplift is limited by faults,and there are a certain number of faults in the interior.The upwelling of hot water in the deep part of the fault zone is of great significance,and faults can become good migration channels of underground fluid.Compared with the depression area,the buried depth of Neihuang uplift is shallower,and the deep heat source is easier to transfer to the shallow stratum through the bedrock,which increases the temperature of the shallow stratum.The surface of the study area is a very thick quaternary stratum with low thermal conductivity,which is a good regional cap rock.In addition,by analyzing the chemical characteristics of groundwater,we can analyze the genesis of geothermal field in the study area.It is determined that the geothermal field in Neihuang uplift is a typical medium low temperature conduction geothermal system,which provides heat for the mantle and crust.The recharge source is atmospheric precipitation outside the area.After long-distance migration,it finally converges in the Ordovician and Neogene strata.The geological factors such as deep heat source,reservoir permeability,thermal conductivity of reservoir cap rock and fault are taken as variables to simulate,and the influence of geological factors on thermal reservoir temperature and reinjection water temperature is discussed.The results show that deep heat source,reservoir permeability and thermal conductivity have little influence on the changes of thermal reservoir temperature and reinjection water temperature,which can be ignored.The higher the thermal conductivity of cap rock,the lower the stable temperature of reinjection water.When the water injection well is above the fault surface and the production well is below the fault surface,and the lower the fault dip angle is,the closer it is to the well,the higher the temperature of the heat storage and the stable temperature of the reinjection water are.