匹配追踪强反射层分离方法及应用

针对油页岩强反射屏蔽储层有效信号的问题,开展了基于匹配追踪的强反射层分离方法研究,目的是较好地弱化强阻抗界面的影响,增强储层有效信号。结合匹配追踪算法和强反射形成机理,首先建立强反射层分离流程，然后基于二维模型,对强反射层分离过程中子波控制参数的选取进行了详细讨论,并提出利用能量增长率作为参数优选的依据。研究认为,当给定1～2 Hz的频率扰动范围、且将匹配子波全部(1倍)从原始记录中减去时,强反射层分离效果最佳。以华北彬县—长武区块油页岩强反射为例,通过对目的层段测井响应特征和地震响应特征的分析,结合模型试验结果确定了子波控制参数,并对油页岩强反射层进行了有效分离。分析表明,强反射层分离后储层弱反射信号得到了有效增强,平面属性能更加客观地反映河道边界和砂体展布特征,井点吻合率达到75%,取得良好的应用效果。

 Aimed at the weak reflection signals shielded by strong reflections from oil shale,we study separating strong reflection horizons from seismic data based on matching pursuit algorithm,which can weaken the influence caused by strong impedance interface to enhance the effective signals. Firstly,combined with matching pursuit algorithm and strong reflection forming mechanism,we establish the workflow of strong reflection horizon separation. Secondly,by 2D model,we discuss wavelet control parameters selection during the procedure of strong reflection separation in detail,and propose that the energy growth rate can be regarded as the basis for parameter optimization. Studies show that the strong reflection horizon separation can achieve best results when the minor frequency disturbance range from 1 Hz to 2 Hz and full matching wavelet subtraction from original records. At last,we take the Binxian-Changwu block in North China as the practical work area,select the wavelet control parameters by the analysis of well loggings and seismic responses from target layers as well as the model test results,and separate the strong reflection events from oil shale effectively. Results show that the reservoir weak reflection signal is enhanced effectively after strong reflection horizons separation,and the plane seismic attributes can reflect the channel boundary and sandbody distribution features more objectively with 75% prediction accuracy,obtaining good practical application effect.