被动源地震勘探反射波成像及其在闽西南矿区立体探测中的应用

矿集区3000米内主要控矿构造和物性结构的高精度、立体表征是深部矿产勘探的重要研究方向。反射地震方法因其分辨率和勘探深度优势，逐步在矿产勘探中应用，但主动源三维反射地震因价格昂贵等因素无法在矿集区三维探测中广泛实施。而无需主动激发，依靠接收活动矿区天然噪声的被动源地震方法则是理想的替代选项。被动源数据通过反射波格林函数计算，重建如主动源激发的拟炮集记录，加之反射地震的数据处理，可实现采集区的三维反射波成像。该方法易于实施，成本只需主动源方法的十分之一。本课题基于理论推导和实践应用之间场源分布、介质特性等差异，就反射波信号分离、震源特性消除、偏移中震源波场提取等关键技术实施增量攻关，以期实现高信噪比的被动源反射地震成像。以闽西南大排矿区为研究靶区，结合前期2D反射地震和面积重、磁资料，借助改进的频谱拓展方法，实现大排矿区选定3D区域的控矿构造和物性结构的精确成像。

High-precision, three-dimensional characterization of major ore-controlling structures and physical structures within 3,000 meters of the ore area is an important research direction for deep mineral exploration. The reflection seismic method is gradually applied in mineral exploration due to its advantages of resolution and exploration depth. However, the active source 3D reflection seismic cannot be widely implemented in the 3D detection of the ore area due to the expensive and difficult acquisition. Instead of active excitation, passive seismic methods that rely on receiving ambient noise from active mining areas are an ideal alternative. The reflect-wave Green function is calculated by continuously-received passive source records, and virtual shot gathers are retrieved, together with reflected seismic data processing, we can three-dimensional seismic imaging profiles. This method is easy to implement and cost only ten percent of the active method. Based on the differences in the field source distribution and medium characteristics between theoretical derivation and practical application, this project conducts research on key technologies such as separation of reflected wave signals, elimination of source characteristic effect, and extraction of shot side wave fields, in order to achieving higher signal-to-noise ratios of passive reflection seismic imaging profile. The subject takes the southwest Fujian Dapai ore area as the research target area, combined with the previous 2D reflection seismic and 3D gravity and magnetic data, with the help of the spectrum extension method, to achieve the accurate image of this ore area. This project will extend the application of this passive reflection seismic method to other exploration filed.