频变AVO影响因素分析

发布时间：2018-06-23 04:43

本文选题：频变 + 反射系数　；参考：《石油地球物理勘探》2017年04期

【摘要】：常规AVO技术是在真振幅恢复后的动校正道集上通过分析振幅(反射系数)随炮检距的变化进行岩性识别和流体预测。因道集上表现出振幅随频率变化特征,且速度也随频率变化,故催生了频变AVO技术。本文对产生频变AVO的速度随频率变化、地层吸收衰减及动校正拉伸等诸因素进行了分析。在速度随频率变化方面,利用White模型,基于三类常见储层分析了频率对速度的影响,并借助弹性、黏弹介质中的AVO理论研究了频散现象对各类储层AVO曲线的影响;在地层吸收衰减方面,基于水平层状衰减模型,定量计算了吸收衰减对AVO曲线振幅、主频及频宽的影响,并分析了其对不同频率成分的影响;还分析了动校正拉伸对AVO曲线振幅、主频及频宽的影响及其引起的频变现象。经计算与分析得知:在地震频段内,地层吸收衰减、动校正拉伸是引起频变现象的主因;对实际地震资料未做吸收补偿、补偿不准或进行常规动校正,都会引起频变现象,只有消除这些影响因素,观测到的频变效应才是储层本身的真实反映。
[Abstract]:The conventional AVO technique is used to identify lithology and predict fluid by analyzing the variation of amplitude (reflection coefficient) with offset on the NMO gather after true amplitude recovery. Because the amplitude varies with the frequency and the velocity changes with the frequency on the gather, the AVO technique of frequency change is given birth to. In this paper, the variation of AVO velocity with frequency, formation absorption attenuation and NMO stretching are analyzed. In the aspect of velocity variation with frequency, White model is used to analyze the influence of frequency on velocity based on three kinds of common reservoirs, and the influence of dispersion on AVO curves of various reservoirs is studied by means of elastic and viscoelastic AVO theory. Based on the horizontal layer attenuation model, the influence of absorption attenuation on the amplitude, main frequency and bandwidth of AVO curve is calculated quantitatively, and the influence of absorption attenuation on different frequency components is analyzed. The effect of NMO drawing on the amplitude, main frequency and bandwidth of AVO curve and the frequency variation caused by it are also analyzed. The results of calculation and analysis show that in the seismic frequency band, the absorption attenuation and NMO stretching are the main causes of the frequency variation, and the frequency variation will be caused if the actual seismic data are not absorbed and compensated, or the compensation is not correct or the routine NMO correction is carried out. Only by eliminating these factors, the observed frequency change effect is the true reflection of the reservoir itself.
【作者单位】：中国石油大学(北京)油气资源与探测国家重点实验室;中国石油大学(北京)CNPC物探重点实验室;
【基金】：国家“863”计划课题“多分量地震裂缝检测与油气识别技术”(2013AA064201)资助
【分类号】：P618.13;P631.4

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