【作者】 孙黄利；

【导师】 李新虎； 朱芳香；

【作者基本信息】 西安科技大学 ， 地质工程， 2010， 硕士

【摘要】 西部煤田地震勘探区主要是以沙漠、戈壁、山地、黄土塬为主要地貌单元,这些复杂的浅表层地震地质条件,对地震勘探中地震波的吸收、衰减都极为严重,导致初至波不清晰,有效的反射信号常常被“淹没”在干扰中,得不到信噪比较高的野外数据采集资料,使得勘探任务难以完成;因此,利用低速带成果约束的初至波层析技术对于解决野外数据采集中的高速层激发技术、资料处理中的静校正问题都具有十分重要的意义。针对西部煤田地震勘探中的复杂表层结构,根据地震波传播的基本原理,先对初至波在表层模型中的传播规律及其类型特征进行了分析研究;然后简要论述了地震初至波旅行时层析成像的基本原理,并利用地震直达波、回折波、折射波以及其组合的初至波和层析反演方法,精确的求取地震波在地下介质中的传播速度,实现了速度任意变化的复杂表层模型的建立。最后通过对山地、戈壁、沙漠、黄土塬区的地震勘探实例的对比分析,采用低速带调查与初至波层析迭代反演建立表层速度建模的方法,建立了精细的表层速度模型,应用于指导野外数据采集中的高速层激发,使得在野外采集中取得了高质量的原始数据;应用初至波旅行时层析静校正,使校正后的叠加剖面煤层反射波连续性好,信噪比高,构造形态和层位之间的对应关系更加清晰,为后续资料的成像处理,提高分辨率处理打下良好的基础,在复杂地表区取得了明显的地震勘探成果。更多还原

【Abstract】 The main geomorphological units in Western coal seismic exploration area are mainly desert, Gobi, mountains, loess plateau and so on, These complex geological conditions in the shallow surface results in serious absorption and attenuation to seismic wave. Consequently first break is not clear. The valid reflected signal is often”drowned" in the interference wave, so a high signal-to-noise ratio field data can not be obtained. It makes exploration project difficult to be fulfilled. Therefore, the first break wave tomography technology constrained with achievement of low velocity zone is significant, especially to high-speed layer excitation techniques for data acquisition and Datum Statics in data processing.First of all, basing on seismic wave propagation principles, the propagation rule and types of first wave in the surface model were analyzed. Then the basic principles of First-Break wave tomography technology were discussed.Using the first break of seismic direct wave, reverse branch, refraction wave and their combination , tomographic inversion was applied to obtain medium velocity underground. Then complex surface modeles can be established.Finally, to different surface types, actual examples were analysed and compared, including mountains, Gobi, desert, loess plateau region . Applying low speed investigation and first break tomographic inversion, the fine velocity model was established, Conducted by the velocity model, high quality raw data were obtained using high velocity layer excitation technique. Appling first break travel time tomography static correction, good continuity and high signal-to-noise ratio stacked section was generated. The well defined structural form and correspondence between layers provieded good foundation to improve the resolution in imaging process sequently. The seismic exploration result was apparent.更多还原