瞬变电磁法在准噶尔盆地南缘静校正中的应用

地表及近地表地质体岩性的纵横向变化是需要对不同波长进行静校正的重要原因之一。在复杂地区的地震勘探中进行常规静校正时,由于受地震微测井或小折射控制点数量的限制,加之相邻控制点之间的岩性变化,致使深度、速度关系差异较大,有时无法准确地建立地表及近地表速度—深度模型,甚至不能求取准确的静校正量。采用瞬变电磁法(TransientElectromagneticMethod),通过连续观测,可以获得地震勘探区地表及近地表结构的电性剖面,利用岩性与电性的关系,建立地表及近地表地质模型。在此基础上,有目的地部署地震微测井或小折射控制点以获取相应的深度、速度数据,从而建立地表及近地表速度—深度模型,可以求取准确的静校正量。这种以表层地质模型为基础建立的地球物理速度—深度模型,其静校正量的求取具有唯一性。

Application of Transient Electromagnetic Method to Static Correction Processing in Southern Margin of Junggar Basin

The vertical or horizontal lithologic variation of geologic bndy in surface and near surface is one of the key factors for static correction of different wave lengths.By using conventional static correction,it is difficult to develop the surfacr of such a depth vs velocity resulted from limitation of numbers of up-hole shonting or weathering-refraction shooting point,along with lithologic changes between adjacent control points.By using transient clectromangnelic method and by continuous survey,the electric seismic profile of the surface or near-surface texture in target area can be oblained ,and the velocity-depth model can be developed by the relationship between the lithology and the electric feature,Furtemore,the accurate statc correction value could be gained by arranging the up-hole shonting or weathering-refraction shoooting points,getting relevant depth and velocity data and them develping relevant model.Such a surface geologic model-based geophysical velopcity-depth model is of uniqueness for gaining the accurate static correction value.