Research Of Three-component Transient Electromagnetic Response

Transient electromagnetic detection is one of the primary methods ofgeophysical exploration. The traditional transient electromagnetic detection onlyutilizes the vertical component of the TEM response, it will be limited when it facesto complex geological structure. It will cause lower detection accuracy andinterpretation error. Response of horizontal component contains a large amount oftarget information. Comprehensive analysis of horizontal component and verticalcomponent response will be more accurate when determining the underground targetbody, and improve the TEM explanation’s accuracy.Nowadays, the theoretical study of transient electromagnetic and research oninstrument development focus on the vertical component Z. The horizontalcomponent is always overlooked. The amplitude of horizontal component response isnot as strong as z component, meanwhile horizontal component response data is verycomplex, resulting that utilize of horizontal component is much more difficult thanthe vertical component.To solve this problem, firstly, this paper pointing out that three-component TEMis superior to one single vertical component TEM. Secondly, three-componenttransient electromagnetic system response expressions are deduced based on the TEMmodel by using a conductive loop as a target. Calculate the X, Y, Z components andanalyze the response characteristics of each response. Lastly, this paper calculated theearth response and other unexpected three-component responses due to the coilinductance of the system.Results of this research show that: X, Y, Z components have respective responsecharacteristics. Z-component responses obviously imply the anomaly. The X-component response roughly determines the position of the target’s center of theground. Meanwhile, the X-component response reflects the dip direction which ismore sensitive than the Z-component response. Y-component response reflects theshape of the target along the direction perpendicular to the survey line. Target location can be determined qualitatively by three-component measurement. Changes in heightof the nacelles greatly affect the response amplitude, but have little effect on theresponse curve. Changes of the nacelle’s angle greatly affect the response curve.Changes of the emission current amplitude greatly affect the response amplitude, buthave no effect on the response curve. The ground response affects the TLR responseamplitude at early time. The TLER and TELR response can increase the TLRresponse amplitude at early time and decrease the TLR response at the late time.The results of this paper could provide theoretical guidance for TEM systemcalibration and TEM three-component data explanation.