CSAMT在火山岩盆地地热勘查中的应用

Application of CSAMT for Deep Geothermal Exploration at the Volcanic Rock Basin

火山岩导水、储水条件差,通常不作为地热勘查目标储层,但火山岩盆地下伏有利地热储层埋深通常较大,勘探风险高,开采成本大。熔结成岩的火山岩具有坚硬、性脆的特点,在断裂带附近具有发育裂隙的条件,因此,寻找火山岩中构造裂隙型地热水是最佳的选择。以江苏扬中北部火山岩盆地地热勘查为例,应用CSAMT电阻率定量反演、阻抗相位定性分析的手段,结合多条测线结果对比,对低阻异常进行筛选,克服静态效应和反演多解性引起的假异常,推断深部导水断裂构造位置,确定最佳钻探井位。钻探验证结果表明,火山岩可以作为地热储层,CSAMT是火山岩盆地地热勘查的有效手段。

With the weak hydraulic conductivity and poor storage conditions,the volcano rocks are seldom taken as the geothermal exploration target reservoirs.It is difficult and high cost to prospect the favorable geothermal reservoir under massive volcanic rock at basins.However,when the rocks such as ignimbrite,have hard and brittle characteristics,the hot groundwater will occur in the faults.In that case,it is the best option to explore the structural fissure water in volcanic rocks.Taking the geothermal exploration at volcanic rock basin in northern Yangzhong as an example,this paper introduces the use of CSAMT resistivity inversion and phase qualitative interpretation techniques for overcoming the static effect and non-uniqueness of inversion.Combined with multiple line work,we select the low resistivity anomalies to determine the distribution of deep structure.Last recommendation well is proposed according to the comprehensive research.Actual data results indicate that CSAMT is effective in geothermal exploration at volcano rock basins.