多波地震勘探及裂缝储层预测研究进展

Recent advances in multicomponent seismic and fractured reservoir characterization

综述多波多分量地震学的基本概念及其在油气储层描述中的应用,并结合中国陆上三维三分量(3D3C)地震勘探实例阐述多波地震勘探的方法技术原理及应用效果。在岩性油气藏勘探中,纵波(P波)和横波(S波)的传播速度和波阻抗的变化可以用来识别岩性圈闭;而在裂缝型油气藏勘探中,由于储层中定向排列的裂缝导致储层具有地震各向异性特征,在多波多分量地震勘探中可以观测到纵波方位各向异性与横波分裂现象。充分利用这些地震波场特征有助于开展对储层中裂缝走向、发育密度及其空间分布情况的定量描述。此外,从多波多分量地震数据中能够提取基于频率变化的地震属性,其中包含有与储层中填充的流体类型与流体赋存空间有关的重要信息。目前在国内外多个油气田开展的多波多分量地震应用实例充分证明了该技术在油气藏储层特征描述方面具有毋庸置疑的技术潜力。尽管如此,多波多分量地震勘探技术的推广应用仍然面临诸多挑战,如陆上多波多分量地震勘探数据采集质量与效率、转换波(PS波)精确成像及多波资料解释等问题。只有不断改进并完善上述问题的解决方案,多波多分量地震勘探技术才有望成为油气勘探的主流技术。

This paper reviews the basic concepts of multicomponent seismology and how it can be applied to characterize hydrocarbon reservoirs, which is illustrated using 3D3 C real data examples from onshore China. Hydrocarbon reservoirs formed from subtle lithological changes, such as stratigraphic traps, may be delineated from changes in P- and S-wave velocities and impedances. Hydrocarbon reservoirs containing aligned fractures are anisotropic. Examination of the resultant azimuthal variations of P-wave attributes and split shear-waves can give us better definition of their internal structures including fracture orientation, fracture density as well as their spatial distribution. Furthermore, frequency-dependent variations in seismic attributes derived from multicomponent data can provide us with vital information about fluid type and distribution. Current practice and various examples have demonstrated the undoubted potential of multicomponent seismic technology in reservoir characterization. Despite all this, there are still substantial challenges ahead. In particular, the data quality and efficiency of onshore multicomponent seismic acquisition, the improvement of converted-wave imaging and interpretation are major hurdles. All of these need to be overcome before multicomponent seismic exploration becomes a main stream technology.