【摘要】 地震勘探在金属矿勘查中发挥越来越重要的作用,但复杂的介质结构和矿体形态通常使金属矿地震解释异常困难,为深入研究复杂金属矿体的地震波场特征,有效开展金属矿地震解释,本文以庐枞矿集区的罗河、泥河和大包庄矿床为例,在详细开展物性测量和地质与地球物理建模的基础上,对均匀介质复杂矿体模型、简化矿体模型和随机介质简化矿体模型进行了金属矿地震波场模拟研究。使用波动方程交错网格有限差分法对模型进行正演模拟,并对模拟结果做叠后偏移处理,分析了各种模型的波场特征,并与实际矿区地震反射剖面进行了对比。结果表明:含磁铁矿、黄铁矿的金属矿体与火山沉积岩、熔岩等围岩都有明显的波阻抗差异,理论上可以用反射地震方法进行深部矿床勘探;对似层状的复杂矿体,当其厚度远大于(4～5倍)地震信号的理论分辨率(λ/4)时,反射地震可以探测复杂矿体的结构形态;当矿体陡倾时,反射能量明显减弱或消失,随机介质与实际介质更接近;当不均匀程度大于5%或更大时,散射噪声将淹没矿体有效反射信号。波场模拟与实际地震剖面对比结果表明,反射地震在实际矿区的应用,面临的挑战要大很多,其中干扰、介质的不均匀性、矿体的形态是影响地震勘探效果的主要因素。更多还原

【Abstract】 Seismic exploration plays an increasingly important role in the metal ore exploration,but seismic interpretation for the ore districts is often extremely difficult due to the complex structures and orebody shape.This article takes Luohe,Nihe and Dabaozhuang mineral deposits in the Luzong ore area as an example to study the wave field characteristics of complex metal deposits and conduct effective seismic interpretation.Based on petrophisical property measurement and geophysical modeling,seismic wave field modeling for metal ores was studied in this article using the models of homogeneous complex orebody,simple orebody,and random simple orebody.Wave equation staggered-grid finite difference method was used to conduct forwarding simulation and modeling results was processed after post-stacked shift.Characteristics of the wave fields produced by various models were analyzed and compared with actual seismic reflection profiles in the ore district.The results show that there are obvious impedance difference between ore body containing magnetite and pyrite and volcanic sedimentary rocks and lava rocks,and theoretically,the reflection seismic method can be used in deep mineral deposits exploration.For the stratiform orebodies,reflection seismic method can be used to presume structure of complex orebody when the thickness is much larger than or 4～5 times larger than the theoretical resolution (λ/4) of seismic signals,but the reflection energy is obvious weakened or fade away when the orebody is steeply dipping.For random medium similar to actual medium,the reflection signal will be submerged in scattering noise when the heterogeneous level is greater than 5%.The comparative analysis of wave field simulation and the actual seismic profiles indicates that seismic reflection method faces great challenges in the actual application,in which interference,heterogeneous medium,and orebody shape are the major factors affecting result of seismic exploration.更多还原