豫北内黄凸起地热田成因机制分析

Causal Mechanism Analysising of Geothermal Field in Neihuang Uplift of Yubei

豫北内黄凸起地热田热储资源较为丰富,区内热储层有新近系明化镇组热储层、新近系馆陶组热储层及寒武系、奥陶系碳酸盐岩岩溶裂隙热储层。应用同位素水文地球化学方法,结合区域地质构造条件,对地热田成因机制进行了系统研究,结果表明:研究区地温场主要受地壳深部结构、地质构造以及地层岩性结构控制,同时受边界断裂导热以及地下水活动等因素影响;该地热田地热水温度偏低,最高约为58℃,属于低温地热系统,区内地热流体的氢氧同位素投影基本落在当地雨水线上,表明地热流体来源于大气降水;地热水的阳离子以Na^+为主,阴离子以Cl^-和SO_4^(2-)为主,地热水为Cl-Na、SO_4-Na、SO_4+Cl-Na型水;研究区地热水来源于西部山区的大气降水,地热水的形成年龄为1.6万~3.2万a。

Geothermal field in Neihuang uplift of northern Henan is one of relatively rich in geothermal resources region in northern Henan Province.There are Neogene Minghua formation thermal reservoir,Neogene Guantao formation thermal reservoir and Ordovician Cambrian Carbonate fracture karst thermal resen,oir in the area.Result from application of isotopic hydrogeochemical method and analyzing the regional geological structure conditions,the genetic mechanism of geothermal field had been systematically studied.The results show that the geothermal field in the study area is mainly controlled by deep crustal structure,geological structure and lithologic structure,meanwhile,it is affected by boundary fracture heat conduction and groundwater activity.The geothermal water temperature in the geothermal field is lower and the highest is about 58,which belongs to the low temperature geothermal system.The hydrogen and oxygen isotopic projection of the geothermal fluid in the area basically falls on the local rainwater line,which shows that the geothermal fluid is root in atmospheric precipitation.The cation of geothermal water is mainly N a+,the anion is mainly C l-and SO4 and the types of geothermal water is C l-N a,SO j-Na and SO4+Cl-Na.The geothermal water in the study area is derived from the precipitation in the western mountain area and the geothermal water formation age is 16 0 00-32 000 years.