松辽盆地古龙页岩油保真宽频宽方位各向异性地震处理技术

Seismic processing technology of fidelity broadband wide-azimuth anisotropy for Gulong shale oil in Songliao Basin

松辽盆地古龙页岩油勘探已见良好前景,实验室测量结果表明古龙页岩具有极强的各向异性和吸收衰减效应,强各向异性会造成速度分析失准,强吸收衰减会造成地震频率降低和波形相位畸变,二者综合影响会降低地震成像结果的保真度和可靠性。为了提高地震处理成果保真度和对井符合程度,消除各向异性和吸收衰减对处理成果的影响,消除断层附近因同相轴成像上翘带来的构造误差,提供保真处理成果和高品质CRP道集。基于岩石物理分析结果和波动方程正演指导下的各向同性速度分析方法,得到平滑准确的初始速度场;应用黏滞声学介质稳相Q偏移展宽频带提高分辨率并更新速度,采用OVT域数据规则化和OVT偏移得到宽方位处理成果用于裂缝预测;结合实验室测量结果和井信息建立场,完成各向异性叠前深度偏移,利用基于Hessian矩阵真振幅恢复技术为叠前反演提供高品质保真CRP道集。研究成果可为地质和工程甜点预测提供高品质的地震处理成果和CRP道集,后验井钻探成果分析验证了该方法的适用性和可靠性,为提高古龙页岩油地震预测符合度提供了有力支撑。

Gulong shale oil in Songliao Basin has a good exploration prospect.Laboratory measurement shows that Gulong shale has extremely strong anisotropy and absorption attenuation effect.Strong anisotropy causes inaccurate velocity analysis and strong absorption attenuation causes frequency reduction and waveform phase distortion.The above two characteristics together reduce fidelity and reliability of seismic imaging.Smooth and accurate initial velocity field is obtained based on isotropic velocity analyzing method guided by petrophysical analysis and wave-equation forward simulation in order to enhance fidelity of seismic processing and well correlation,eliminate influences of anisotropy and absorption-attenuation on processed results,eliminate structural error caused by up-warping of events near the fault,and provide fidelity processed results and high-quality CRP gathers for seismic prediction.Viscous acoustic media phase stabilization Q migration is applied to widen frequency band,improve resolution and update velocity,wide azimuth processing used for fracture prediction are obtained by using OVT data regularization and OVT migration.Combined with laboratory measurements and well information,and fields are established and anisotropic PSDM is performed,and high-quality fidelity CRP gathers is provided for prestack inversion by means of true amplitude recovering technique based on Hessian matrix.The study results provide high-quality seismic processing results and CRP gathers for geological and engineering sweet-spots prediction.Applicability and reliability of the method are verified by drilling data analysis,providing support for enhancing seismic prediction accuracy of Gulong shale oil.