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    基于OBC数据方位优选的甜点叠前预测技术及应用以涠西南凹陷流三段为例

    Prestack sweet spotting based on OBC data azimuth optimization: A case study of Liu3 Member in Weixinan Sag

    • 摘要: 针对涠西南凹陷流沙港组三段(流三段)夹层型页岩油储层钻井少、地震资料分辨率低、甜点预测精度低的难题,提出了一种基于海底电缆(OBC)地震数据方位优选的叠前波形指示反演技术。首先,在岩石物理交会分析的基础上,基于纵波阻抗和横波阻抗交会图的坐标旋转及旋转角度迭代优化,构建了页岩油甜点敏感因子;其次,在区域地质认识指导下,基于“平行物源方向,垂直主干断层方向”的原则,优选了OBC地震数据的优势方位,确定了页岩油甜点预测的优势方位地震数据;最后,基于方位优选后的地震数据进行了叠前波形指示反演,刻画了涠西南凹陷流三段夹层型页岩油甜点的空间分布特征。实钻结果表明,基于OBC地震数据方位优选的页岩油甜点叠前预测技术可以在稀疏井控制下实现甜点储层的精细预测,钻井吻合率超过80%,为海上少井区页岩油勘探提供了有效的技术支撑。

       

      Abstract: To address the challenges of limited drilling data, low seismic resolution, and low accuracy of sweet-spot prediction for interbedded shale oil reservoirs in the third member of the Liushagang Formation (Liu3 Member for short) in the Weixinan Sag, a prestack meme inversion technique is proposed based on azimuth optimization of ocean-bottom-cable (OBC) data. A sweet-spot sensitive indicator is established through coordinate rotation of PI-SI cross plot and iterative optimization of the rotation angle based on petrophysical analysis. Under regional geologic constraints, predominant OBC azimuths for sweet-spot prediction are optimized to be parallel to provenance direction and perpendicular to major fault strike. Using optimized azimuthal data, prestack meme inversion is performed to characterize interbedded shale oil sweet spots in the Liu3 Member. Drilling results show that the method enables high-precision prediction of sweet-spot reservoirs even with sparse well control, achieving a success rate of well drilling over 80%. This approach provides an effective technical solution for offshore shale oil exploration with limited wells.

       

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