自然伽马曲线重构波阻抗反演在勘探含铀有利成矿砂体中的尝试

An attempt to find favorable uranium-bearing sand bodies by reconstructed wave impedance inversion using natural gamma curve

【研究目的】在砂岩型铀矿勘查中,利用地震工作手段及传统波阻抗反演,可有效地区分砂、泥岩,却受限于波阻抗差异微小无法区分砂岩中是否含矿。【研究方法】为了寻找含铀有利砂体,本次工作尝试了利用对含矿最为敏感的自然伽玛曲线联合声波曲线重构波阻抗,以提高反演结果对储层含铀信息的甄别能力,弥补传统波阻抗反演对含铀砂体和非含铀砂体无差异地球物理响应的缺陷。【研究结果】经多个钻探实例验证,该方法确实有效增强了波阻抗反演对岩层属性的描述能力,缩小找矿范围,提高了钻探验证见矿率。【结论】自然伽马曲线重构波阻抗值得在利用石油资料二次开发的砂岩型铀矿勘查中推广。

This paper is the result of mineral exploration engineering.[Objective]During the exploration of sandstone-type uranium deposits,the seismic exploration and traditional wave impedance inversion can effectively distinguish sandstone and mudstone,whereas the small difference of wave impedance cannot distinguish whether the sandstone contains uranium.[Methods]In order to find favorable uranium-bearing sand bodies,this paper attempts to reconstruct wave impedance by combining acoustic curve with natural gamma curve,which is most sensitive to uranium ore bodies,so as to improve the inversion ability to uranium-bearing reservoir stratum.This work can make up for the defect that the traditional impedance inversion has no significant geophysical difference of uranium-bearing sand bodies and barren sand bodies.[Results]It has been verified by several drilling cases,and this method effectively enhances the describing ability of rock properties with wave impedance inversion.It also effectively reduces the scope of prospecting and improves the ore finding rate of drilling verification.[Conclusions]Reconstructed wave impedance inversion using natural gamma curve is worthy to be popularized in the exploration of sandstone-type uranium deposits by using petroleum data.