论文详情
利用地震反射纵波的方位各向异性信息预测地下裂缝的发育和分布情况一直是地球物理学家研究的热点课题,常规方法是使用两项Ruger线性近似公式反演得到裂缝相对密度和走向,其计算结果存在多解性且只能计算入射角较小的情况。对任意对称面各向异性介质的纵波方位各向异性弱反射系数近似公式进行整理,结合Schoenberg线性滑移理论,得到纵波方位各向异性反射系数近似公式的傅里叶级数展开公式,给出了基于傅里叶级数展开的纵波方位地震数据裂缝预测方法。将该方法应用于辽河油田雷家地区沙河街组白云岩储层的裂缝预测,并与常规各向异性反演结果及实际成像测井数据进行对比,验证了方法的有效性。研究结果表明,该方法计算简单且不受入射角度的限制,预测的裂缝相对密度与常规反演方法预测的结果精度近似,与成像测井资料吻合,故可作为传统方法的验证和补充。
The application of anisotropic information of seismic reflection wave amplitude in underground fracture development and distribution prediction has always been a hot subject in geologists’ study.The conventional method,which adopts Rugers two-term linear formula to inverse the relative density and direction of fractures,obtains non-unique solutions and can only be applied with small incidence angles.To improve the method,the approximate formula of P-wave weak reflection coefficient varying with incidence-angle and azimuth-angle in arbitrary symmetric anisotropy media was rearranged.Based on the Schoenberg’s linear slip theory,the Fourier series expansion of P-wave azimuthally anisotropic reflection coefficient approximate equation is obtained.The Fourier series expansion of P-wave seismic data with different azimuth was applied in fracture prediction.It is applied in dolomite reservoir fracture prediction in Shahejie Formation,Liaohe Oilfield.The method is proved to be effective and reliable by comparison on the results with the conventional anisotropic inversion method and actual FMI data.The study shows that the method is simple in calculation and is not limited by the range of incidence angle.Meanwhile,the prediction accuracy of fracture density is close to conventional inversion method and the result agrees well with the FMI data.
中国石油天然气股份有限公司科技重大专项子课题“深层地震资料保幅处理与叠前储层描述新技术”(2014E-3204)资助。