张量可控源音频大地电磁法的应用实例

可控源音频大地电磁法(CSAMT)的最大特点是采用人工场源,大大增加了电磁信号强度,弥补了天然场源信号微弱、不易观测等缺点,已被广泛应用到矿产普查、油气勘探、水文环境等方面,并发挥了巨大的作用。此外,它还具有工作效率高,利用一个偶极发射可以在两侧扇形区域内测量;水平和垂直分辨率较高,高阻屏蔽作用小等优点。但是,由于这些年一直采用的是赤道偶极装置的标量测量,其缺点一是标量测量适合简单的地质环境,不适合复杂地质条件勘查;二是由于观测范围受单一偶极发射装置的限制,在长剖面观测或者区域观测中,常常需要调整发射源的位置,若发射源布置在断裂构造上,由于场源效应会导致无法处理多个发射源的观测数据。随着近几年德国Metronix公司的张量CSAMT发射装置的研制成功,通过求取张量阻抗要素,更适合探测二维、甚至三维地质结构,并且还可以在发射装置周围进行全方位观测。随着该仪器的引进,在安徽省两个矿区进行了张量CSAMT试验,通过与标量CSAMT对比结果表明,张量CSAMT可利用阻抗分解技术能有效地分析地质结构等信息,有助于复杂构造勘查,也将会促进CSAMT法的应用与发展。

The Applicationof Tensor CSAMT Method

One of the noticeable characteristics of controlled source audio-frequency magnetotelluric method（CSAMT）is the application of artificial source,thus the electromagnetic signal strength can be greatly increased,and the deficiencies of the natural source like weak signal and poor observation can be made up.This method has been widely used inmineral prospecting,oil and gas exploration,hydrological environment investigation,etc.,and has played a great role.However,in the past years,dipole device of scalar measurement is used,which is suitable for the easy geological environment rather than complex ones.The second deficiency is the observation limit of single dipole transmitter.The position of source is needed to be adjusted in long section observation and area observation.When the source is arranged on the fracture structure,source effect will cause the difficulty in processing those data.In recent years,the tensor CSAMT launcher was successfully developed by Germany Metronix Corporation.This method can calculate the tensor impedance element,which is more suitable for detection of 2D/3Dgeological structure and observation in the transmitter around.With the introduction of the GMS07instrument,two tests in mineral areas of Anhui province had been done.Compared with scalar CSAMT results,tensor CSAMT shows that it can make use of decomposition technique to analyze the geological structure information,which helps the exploration of complex structure,and it will also promote the development of CSAMT method.