横向速度变化对构造成像影响的物理模拟研究

Physical modeling research for the effect of lateral velocity on structural imaging

（中国石油化工股份有限公司勘探开发研究院南京石油物探研究所，江苏南京210014）

Institute of Geophysical Prospecting, Research Institute of Petroleum Exploration and Development, SINOPEC, Nanjing 210014, China

塔河地区低幅度构造普遍发育，由于地层速度横向变化大，目的层埋藏深，局部构造难以落实，因此，加大了勘探风险。为此，利用物理模拟技术探讨了横向速度变化对构造成像的影响。建立了上覆变速层的背斜构造模型，并对物理模拟实验结果和偏移处理效果进行了分析。由于上覆变速层的影响，时间剖面上构造形态被改变，构造高点发生位移，常规时间偏移方法和常用的几种时深转换方法均不能得到正确的深度构造成像结果。利用物理模型建立了与实际情况较为符合的深度域层速度模型，对物理模拟数据进行了深度偏移处理，在深度偏移剖面上，原始地层和构造的几何形态基本得到了恢复。

In Tahe area, low relief structures are widely developed. In addition, the changes in lateral velocity of stratum greatly and the target zones deeply buried, making it hard to recognize local structures, increasing the risk of exploration and development. Therefore, the effect of lateral velocity alternation on structural imaging was discussed by using physical modeling technology. The anticline structure model of overlaying variable velocity layer was established and the physical modeling testing and migration processing analysis carried out. Affected by overlaying variable velocity layer, the structure shape changed on time profile and the structural high shifted, making the structural form unable be identified. But the accurate structural imaging in depth can not be obtained by using the conventional time migration method and depth conversion method. The interval velocity in depth domain suitable for actual data was established through physical modeling. Depth migration processing was proceeded on physical modeling data. On depth migration profile, the geometric shape of original formation and structure was fundamentally recovered.