CRP道集优化处理及其在大庆油田S区的应用

CRP gather optimal processing and its application to S area of Daqing oilfield

叠前反演已在流体预测中广泛应用,其预测精度和应用的反演方法有关,同时叠前反演主要应用叠前偏移的地震数据,地震成像效果和CRP道集的质量对叠前反演的效果具有很大的影响。大庆油田S研究区,Kirchhoff积分叠前时间偏移道集中存在信噪比低、随机噪声能量强、层间多次波、道间能量不均等问题,为有效开展叠前反演计算,需要进行针对上述问题的一系列地震资料预处理,在对地震数据采集和处理参数分析的基础上,应用Radon变换、叠前随机噪声衰减和分偏移距能量补偿等方法,有效提高了地震资料的信噪比,并对道集能量进行了有效补偿。对研究区地震资料处理前后的道集、合成地震记录、叠加剖面以及正演道集与实际道集对比分析证明,道集优化处理有效提高了道集质量,优化处理后的道集可应用于后续的叠前反演和储层预测中。

Prestack inversion has an extensive application in the hydrocarbon and fluid prediction.Inversion algorithms as well as the quality of input seismic data often exhibit direct impacts on its accuracy.At the same time,prestack inversion mainly uses prestack migration seismic data.The effect of seismic imaging and the quality of CRP gather as the basic data of prestack AVO/AVA inversion has a great influence on the inversion results.In this paper,the S area of Daqing oilfield was taken as an example.There are plenty of problems in Kirchhoff integral prestack time migration gather,such as low signal-to-noise ratio,strong random noise energy,internal multiple and uneven energy between traces.In order to effectively carry out prestack inversion calculation,the authors take into account the acquisition and processing parameters of seismic data and consider that a series of seismic data pre-processing should be carried out to solve these problems in seismic survey.On the basis of numerical analysis,Radon transform,Prestack random noise attenuation and Offset energy compensation are used to effectively improve the signal-to- noise ratio of seismic data and to compensate gather energy.Radon transform can effectively suppress regular interference such as multiple waves,prestack random noise attenuation can suppress random noise in CRP channel and Offset energy compensation can effectively restore the AVO characteristics of seismic data.After optimization,the continuity and resolution of CRP gathers are improved to a certain extent,and the characteristics of wave groups are clearer.After de-noising,the amplitude plane attributes of CRP gathers before and after optimization are compared and analyzed.It is further shown that the abnormal energy of CRP gathers at the section is well suppressed and the transverse seismic waves are suppressed.The amplitude and energy characteristics of the seismic data are relatively balanced,that is to say,the optimization processing enhances the lateral contrast of seismic data,which is conducive to seismic attribute feature extraction,sand body characterization and reservoir prediction.The comparison and analysis of gathers,synthetic seismograms,stacked sections,forward gathers and actual gathers before and after seismic data processing in the study area show that the gather quality is effectively improved by gather optimization processing,and the optimized gathers are applied to subsequent prestack inversion and reservoir prediction.