浅层电性资料在英雄岭地区低降速带的应用效果

Studying shallow low-velocity zone using electric data

青海柴达木盆地英雄岭地区地表地质条件非常复杂,在不同地段低降速带的速度和厚度变化差异较大,严重影响地震勘探的效果。本文通过对英雄岭-油砂山地区三维MT(大地电磁测深法)资料和英雄岭-干柴沟地区三维AMT(高频电磁测深法)资料进行浅部高阻层与低降速带关系的研究,确定了该地区低降速带的厚度分布情况,并通过改良斯特经验公式以及拟合参数的确定,进一步获得了该地区低降速带的速度变化范围,经与微测井和小折射速度资料对比,认为其结果基本反映了该地区低降速带的变化趋势,可用于地震资料的静校正、速度建模。

Geology condition of the earth surface is extremely complicated in Yingxiongling area in Qaidam Basin.Velocity and thickness of low-velocity zones are quite different from one place to the others,which cause statics problems for seismic exploration.Using magnetotelluric sounding(MT) data acquired in Youshashan and high frequency electromagnetic sounding(AMT) data acquired in Ganchaigou,we study shallow low-velocity zones in order to find out its thickness and velocity variation trend.Low-velocity zone thickness and its distribution are determined by the relationship between shallow high-resistivity layers and shallow low-velocity layers.Velocity variation of low-velocity zones is determined using our improved Faust experience formula and fitting parameters.Our electric data results are consistent with uphole data and LVL data,which can be used for static corrections and velocity model building.