泌阳凹陷南部陡坡带地震资料的炮域波动方程叠前深度偏移

泌阳凹陷南部陡坡带是河南油田的重点勘探老区,其构造产状不仅陡,断层也多,叠后时间偏移难以得到较好的地震成像效果,基于Kirchhoff积分偏移方法具有运算速度快、效率高的特点,以及炮域波动方程方法能保持地震波的动力学特征,应用Kirchhoff积分偏移方法进行了偏移速度分析,建立了精细的速度模型.然后基于该模型在深度域进行了剩余速度分析以及层析成像,进一步提高了速度模型的精度. 通过分析偏移孔径、去假频参数以及延拓步长等成像处理参数对成像效果的影响,确定出最佳偏移处理参数,最后利用炮域波动方程方法对工区的三维地震数据进行了叠前偏移成像.成像结果表明,该方法能够使该区陡坡带反射层位得到较好的偏移,信噪比和横向分辨率都得到提高.

Wave-Equation PreSDM in Shot Domain of Seismic Data from Steep Slope Zone in Southern Biyang Depression

The steep slope zone in southern Biyang Depression is a main oil production region in Nanyang Oilfield,which involves deep structures and numerous faults.This makes it difficult to obtain good effect of seismic imaging by post-stack time migration.Because of this,the study takes full advantage of prestack depth migration(PreSDM) of Kirchhoff integral migration method with fast calculation and based on wave-equation in the shot domain to preserve dynamic features of seismic waves.PreSDM of Kirchhoff integral was selected for migration velocity analysis of structural imaging and the establishment of a refined interval velocity model.Meanwhile,residual velocity analysis and tomography were used to raise the accuracy of velocity model in the depth domain.The optimum parameters for migration process are determined by analyzing the effect of imaging parameters on imaging result with migration aperture,anti-alias frequency and extrapolate step.Finally,preSDM is performed to image 3D seismic data in the area by wave-equation in the shot domain.The imaging results show that the reflectors of the steep slope zone can be migrated well with better S/N and lateral resolution.