综合物探方法在隆起型地热田找矿中的应用

    Application of comprehensive geophysical prospecting method in uplift geothermal field

    • 摘要: 以厦门香山湾地热田勘查成果为例,综合运用可控源音频电磁测深法、视电阻率联合剖面法及视电阻率测深法,寻找与断裂有关的地热水富集地段,并根据异常解释圈定钻孔靶区。结果表明: 可控源音频电磁测深法可高效地解译、推测研究区断裂的空间分布特征,分析并确定可能的地热水富集地段; 垂直推测断裂走向布设视电阻率联合剖面及视电阻率测深剖面,可对可控源音频电磁测深法推测的断裂进行验证,并进一步确定地热水富集地段断裂的产状,有效排除物探解译结果的多解性; 选择多组断裂上盘形成的交叉地段作为地热地质钻探的最佳靶区。钻探结果显示: 厦门香山湾地热田单井涌水量41.76 m3/h,水温52 ℃,地热流体可溶性总固体含量为6 183.19 mg/L,水化学类型为Cl-Na型。

       

      Abstract: In this paper, the authors have taken Xiangshanwan geothermal field in Xiamen as an example to detect the fault related geothermal water enrichment areas and determine the optimum borehole position based the Geophysical anomaly, combined with the comprehensive geophysical prospecting method of Controlled Source Audio-frequency Magneto Tellurics (CSAMT), joint resistivity profiling and resistivity sounding. The results show that the CSAMT method is efficient and reliable to prospect the spatial distribution characteristics of fault structures in the study area, and it can be used to determine the possible areas of geothermal reservoir. The joint resistivity profiling and resistivity sounding are arranged vertically along the strike of the inferred fault structures to verify the fault structures inferred by the CSAMT method, which would further determine the occurrence of the fault structures in the geothermal water enrichment section and eliminate the multiple interpretational nature of geophysical prospecting method. Finally, the cross region formed by the hanging wall of multiple groups of fault structures is selected as the best borehole target area for geothermal geological drilling. The drilling results show that the single well yield is about 41.76 m3/h, and water temperature is of 52 ℃, with the total soluble solid of 6 183.19 mg/L and the water type of Cl-Na in Xiangshanwan geothermal field.

       

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