瞬变电磁法在准噶尔盆地南缘东部台28井区近地表调查中的应用

APPLICATION OF TEM FOR SHALLOW GEOLOGICAL STRUCTURE INVESTIGATINGIN THE FOOTHILL IN SOUTHERN JUNGGAR BASIN

瞬变电磁法(TEM)是近年来国内外发展速度较快、应用效果较好的一种电磁方法,由于其施工便利、成本低廉、工作效率高、应用效果明显等优点,已广泛应用于金属、煤炭、地下水等矿藏勘查.该方法应用于地震勘探中的表层结构调查,虽不能直接得到近地表地质体岩性信息.但可通过连续观测获取不同岩性间电性差异信息,根据电性相对关系得到准确的近地表地质体形态和岩性分布规律,为地震资料后续处理提供可靠的静校正量.瞬变电磁法勘探深度由浅层5 m到中深层300 m左右.准噶尔盆地南缘东部台28井区勘探实例表明,通过电性分层、小折射和地震微测井成果资料综合解释,在表层结构建模和计算静校正量方面取得良好效果.

In the marginal zone of one of oil-fields in Jungar basin, we have putted in practice Coincident-Loop Configuration TEM for shallow geological structure investigating. In order to image continuously and intuitionistic the vertical variety of the conductive layer underground, a new definition of all-time apparent resistivity which is called pseudoall-time apparent resistivity is used for data processing. Forward modify method is used for data inversing. In this article, ＂non-linear high order polynomial fit method ＂,a new technology is also introduced to transform resistivity profile into velocity profile under the control of a little micro-well logging. Kriging interpolation method is used for calculating the planar velocity distribution of low velocity zone from five profiles TEM data.Results indicated that this method can be used for studying subtly the variety characteristic of electric parameters of subsurface layer within 10 to 300 meters depth range..The layer electric interface determined from TEM data is comparable to the velocity interface from micro-well logging. It is feasible to provide static correction data for 3-D seismic zone by TEM method. Also, test shown that Static Correction effect is better by TEM than other method.