面向复杂山前带的平滑地表TTI各向异性速度建模

山前带“复杂地表、复杂地下”的双复杂地震地质条件给深度域速度建模带来很大困难,且影响了构造落实和储层预测的可靠性,为此提出了面向复杂山前带的平滑地表TTI各向异性速度建模技术流程。首先选取接近真实地表的小平滑地表面作为建模和成像的基准面,然后利用近地表回转波层析和中深层全局常速度填充延拓建立初始速度模型,避免了常规方法存在的近地表和中深层速度拼接问题,再通过VSP测井速度标定和一维成像道集正演,求取各向异性参数,建立面向山前带的TTI各向异性初始速度模型,最后采用层位控制的层析反演技术,提高山前带速度模型精度,实现速度快速收敛。西部某山前带工区实际资料处理结果表明,该流程较好地适应双复杂地质条件,可以更新各向异性参数模型,精细刻画出工区内近地表巨厚高速砾岩层和深部低速膏盐体,提高深层盐下构造成像质量。实际资料处理结果也验证了该流程的有效性,为复杂山前带油气勘探提供了有效的技术支撑。

The complex surface and geological conditions of piedmont zones brings challenges to velocity modeling,structure identification,and reservoir prediction.To address this issue,a tilted transversely isotropic (TTI) anisotropic velocity modeling based on a smoothed surface was proposed.First,a smoothed surface close to the actual surface was taken as the reference plane for velocity modeling and imaging.Then,diving wave tomography was used to establish a near-surface velocity model,in which constant velocity values in the middle and deep layers were initially set.Subsequently,velocity calibration from vertical seismic profile (VSP) logging was carried out,combined with one-dimensional forward modeling of the imaging gather,so as to obtain the anisotropic parameters and establish the initial TTI anisotropic model for the piedmont zones.Finally,horizon-controlled tomography was utilized to achieve fast convergence and derive the final velocity model.Test results on field data have demonstrated the effectiveness of the proposed method,which may be helpful for oil and gas exploration in complex piedmont zones.

国家自然科学基金企业创新发展联合基金(U19B6003)资助。