日照东部地区地热资源成因分布规律及勘查定井方法研究

日照东部地区具有较好的地热成矿条件及地热找矿前景。研究地热资源的成因、分布规律,对寻找地热资源具有重要的指导意义。本文在介绍日照东部地区地热资源分布特征和赋存规律的基础上,结合地热勘查及施工的成功经验,针对日照东部地区特殊的地热地质条件,采用可控源音频大地电磁测深(CSAMT)、电磁测深(VES)等方法对典型地热勘查区断裂构造特征及富水性进行解译,并确定地热井位,通过钻探施工及岩矿测试研究地热水成因。结果表明:日照东部花岗岩地区地热资源主要分布在NE向、NNE向及NW向断裂交会带附近,为断裂控制的深循环对流型带状地热资源,热储分布主要受断裂控制;勘查定井宜选择在2条或多条断裂的交会处;可控源音频大地电磁测深对断裂深部发育特征及裂隙含水情况反映明显,可作为花岗岩地区地热勘查定井方法;氢氧同位素检测结果反映研究区内地热水为大气降水补给,补给区为周边山区就近补给,沿断裂入渗循环,吸收热量形成地热水,循环距离不大。

Study on the Origin Distribution Law and Exploration Well Fixing Method of Geothermal Resources in Eastern Rizhao City

Eastern area in Rizhao city has good geothermal mineralization conditions and geothermal prospecting prospects. Study on the origin and distribution of geothermal resources has important guiding significance for searching for geothermal resources. Based on distribution characteristics and occurrence rules of geothermal resource, combining with successful experiences of geothermal exploration and construction, pointing to speicial geothermal and geological conditions, by using controllable source audio magnetotelluric sounding (CSAMT), electromagnetic sounding (VES) and other methods, characteristics of fault structures and water richness in typical geothermal exploration areas in Rizhao area have been interpreted, and geothermal well positions have been determined. The origin of geothermal water has been studied through drilling construction and rock and mineral testing. It is showed that geothermal resources in the eastern granite area of Rizhao city are mainly distributed near the faults with the trend of NE, NNE and NW. It is a deepcycle convective zone geothermal resource controlled by faults, and the distribution of heat storage is mainly controlled by faults. It is appropriate to survey and fix wells at the intersection of two or more faults. The controlledsource audiofrequency magnetotelluric sounding method can clearly reflect the deep development characteristics of the faults and the water content of the fractures, which is a more suitable method for geothermal exploration and well positioning in granite area in Rizhao city. According to hydrogen and oxygen isotopes results, it is reflected that geothermal water in the study area is supplied by atmospheric precipitation, which is supplied by the nearby mountainous area. It infiltrates and circulates along the fault, and absorbs heat to form geothermal water. The cycle distance is not large.