粘弹性介质地震波聚焦成像技术

来源期刊：中南大学学报(自然科学版)2001年第3期

论文作者：张建贵 宋守根 袁修贵 张荣峰

文章页码：231 - 234

关键词：粘弹性介质;波场;聚焦成像;多尺度;塔里木盆地

Key words：viscoelastic medium; wave field; variable focus imaging; multiscale; Tarim Basin

摘    要：在复杂地质条件和深层油气资源的勘探中,基于声波方程的常规地震勘探技术的局限性日益突出.作者在以大地介质为粘弹性介质的前提假设下,推导出基于三阶波动方程的波场外推公式,分析了上行波随传播距离的增加而逐步丢失其高频成分的原因.并以小波分析为工具,提出了粘弹性介质地震波聚焦成像技术.这种方法不同于Bleistein的线性化方法,是通过1个虚拟的中间波场用多尺度方法去重建真实的地下波场,进而成像.同时,利用小波分析的时频局部性特征和优良的去噪功能,提高了成像的质量.通过用常规的处理技术和聚焦成像技术对塔里木盆地实际地震资料进行对比实验,结果表明采用新方法取得了较理想的成像效果,能够较好地解决沙漠、戈壁等厚低速层覆盖下的地震勘探高品质成像问题.

Abstract: In the deep and complicate petroleumexploration, the limitation of the classical methods based on elasticity equation is increasing. In this paper, we suppose that the earth medium is viscoelastic, deduce a new formula about wave field extrapolation from Stock′s Equation,and analyze the cause that the up-wave gradually loses its high-frequency along with its propagation. Based onwavelettrans form, we obtain the technique of seismic wave′s variable focus imaging in viscoelatic medium (TVFI). This method is very different fromN. Bleistein′s linearized method. First the TVFI through a fictitious wave field, uses multiscale algorithmto reconstruct the truewave field,and then takes shape image of the structure under the ground. At the same time, the TVFI also makes use of the time-frequency local character and the fine eliminating noise ability of wavelets, which enhances the quality of imaging. In Tarimbasin,comparing it with the classical methods, the effectiveness of the new method is obvious, proving that the TVFI can solve the difficult problem of seismic imaging in the area which is covered with thick low-velocity medium.