大规模气云区成因分析——以渤海湾A油田为例

渤海湾A油田气云模糊区规模大，气云影响范围内纵波地震资料品质差，构造形态难以确定。通过分析地震、VSP、地质等多种资料，建立了多个二维、三维模型并完成声波方程正演模拟与数据评价。研究认为浅层大范围非均质地层（浅层气）引起的地震波散射屏蔽效应是造成气云区成像模糊的重要原因，垂直浅层气长轴方向的洼陷构造进一步增加了现有三维地震数据（沿浅层气长轴方向采集）成像难度。实际数据处理表明，回转波层析反演浅层速度以及考虑多波至的波动方程类叠前深度偏移等技术能够改善气云区纵波成像效果。

Origin analysis of the large-scale shallow gas-obscured zone: an example of the Oilfield A,Bohai Bay

A large-scale gas cloud zone in the Oilfield A,Bo-hai Bay causes poor quality of P wave data,so subsurface structures are very difficult to be depicted.Based on multi-discipline information including surface seismic,VSP,and geologic data,we build a number of 2D and 3D models and achieve the forward modeling based on acoustic equation and synthetic data evaluation.According to our research,the seismic wave scattering caused by shallow large-scale heterogeneous stratum(shallow gas zone) is an important reason for blurring seismic imaging of gas cloud zone.The sag structure perpendicular to the long axis direction of shallow gas further aggravates the imaging difficulty on existing 3D seismic data(acquisition along the long axis direction of shallow gas zone).Real data processing shows that the near-surface velocity provided by turning-ray tomography,and wave equation prestack depth migration(PSDM) with multi-wave arrivals can improve the imaging quality of P-wave in the gas cloud zone.