CSAMT在碎屑岩地区地热勘查中的应用  

Application of CSAMT to Geothermal Exploration in the Clastic Rocks

作　　者：尚通晓[1,2] 关艺晓[1,2] 闵望[1,2] 刘晓瑜[1,2] 梅荣[1,2] 

机构地区：[1]国土资源部地裂缝地质灾害重点实验室,南京210046 [2]江苏省地质调查研究院,南京210046

出　　处：《城市地质》2015年第4期77-82,共6页Urban Geology

基　　金：中国地质调查局"江苏省地热资源现状调查评价与区划"(12120113077300)

摘　　要：碎屑岩因质软,导水、储水条件不良,通常作为地热有利保温盖层,而碎屑岩电阻率普遍低,厚度大的情况下形成低阻屏蔽层,勘探下伏有利储层难度极大,寻找碎屑岩中构造裂隙水是最佳的选择。但碎屑岩中的储水构造与围岩电阻率差异小,构造迹象微弱,因此在碎屑岩地区找地热技术含量较高。茅山镇位于句容盆地东缘茅山西侧,沉积了厚度超过1800m的白垩系碎屑岩,水文地质条件较差,本文应用CSAMT大范围普查、小范围精细查证布置方式,采用磁场插值校正的技术手段、收发距选取优先保证信噪比的思路,控制白垩系碎屑岩中储水断裂构造,克服低阻的碎屑岩地区构造异常微弱的难点。钻探验证结果表明,CSAMT可以经济有效地应用于碎屑岩地区地热勘查。Clastic rocks may be formed as the favorable geothermal heat cap, because they have such characteristics as lower conductivity and storage of water, and soft texture. However, the lower electronic resistivity of clastic rocks is easy to form the lower resistivity shielding layer under a large thickness. In this case, it is diffi cult to prospect the favorable geothermal reservoir underlain in the massive clastic rocks, and it is necessary to fi nd structural fi ssure water in clastic rocks. However, structural signs are not so obvious because of small resistivity difference between the structure of the storage water and surrounding rocks. So it needs utilizing the high-tech to fi nd geothermal resources in the clastic rock area. The investigation area is located in Maoshan town, on the west of Maoshan Mountains, belongs to the eastern margin of the Jurong-Basin. According to the borehole data, it estimates that there are more than 1800-meter thick layer of Cretaceous clastic rocks deposited in the investigation area with the poor hydrogeological conditions. We used the CSAMT to survey generally in wide range, and to check accurately in small range. In addition, we adopted the magnetic fi eld interpolation correction techniques, and guaranteed fi rstly the noise-signal ratio in the selection of transmit-receive distance. By these methods, we have found out the water-bearing fault structure, and overcome the exploring problems in the clastic rocks with low resistivity. The drilling results also show that the CSAMT is economic and effective in the geothermal exploration of clastic rocks.

关 键 词：地热 CSAMT 碎屑岩 静态效应 白垩系 

分 类 号：P314[天文地球—固体地球物理学] P631.3[天文地球—地球物理学]