基于正演模拟的高速底砾岩振幅屏蔽特性分析及补偿  

Analysis and compensation of amplitude shielding characteristics of high-velocity basal conglomerate based on forward modeling

作　　者：明君 彭刚 王建立 MING Jun;PENG Gang;WANG Jianli(CNOOC Tianjin Branch,Tianjin 300459,China)

机构地区：[1]中海石油(中国)有限公司天津分公司,天津300459

出　　处：《石油物探》2022年第6期1065-1076,共12页Geophysical Prospecting For Petroleum

基　　金：中海石油(中国)有限公司综合科研项目(YXKY-2019-TJ-02)资助。

摘　　要：部分海上探区发育不稳定分布的高速底砾岩,其在地震勘探过程中对下伏地层的成像产生强振幅屏蔽,导致地震资料品质降低,不利于构造、储层、储量的精细研究及油气开采。首先对被屏蔽层位的深度和底砾岩的长度、厚度、层数以及速度分别建立了一系列正演模型;然后对不同速度模型的正演模拟数据进行振幅屏蔽特性分析,沿层位进行振幅值的统计,生成沿层振幅曲线;再量化分析影响振幅屏蔽强弱的因素及屏蔽范围,结果发现高速底砾岩下伏地层随着深度的增加,所受到的振幅屏蔽效应逐渐减弱,底砾岩介质中波的传播速度越高,对下伏地层的振幅屏蔽越强,引起的下伏地层反射能量强度变化最高可达60%;最后分别从地震数据采集和处理两个角度,针对屏蔽区域的能量补偿问题,提出了“增加照明范围”和“Q-RTM”两个技术方案,并以正演地震数据和实测地震数据验证了方案的有效性。During seismic exploration in some marine exploration areas,strong amplitude shielding to the imaging of the underlying formations is generated by the unstable distribution of basal conglomerates,which hampers the quality of seismic data and influences the geological assessment of the area.This study first established a series of forward velocity models considering the depth of the shielded horizon and the length,thickness,and number of layers of basal conglomerate.Subsequently,the amplitude shielding characteristics of the forward modeling data in different velocity models were analyzed.The amplitude values along the horizons were studied,and the amplitude curve along the layer was generated.The quantitative analysis revealed that the amplitude shielding effects of the underlying high-speed basal conglomerate formation weakened gradually with increasing depth.When the velocity of the basal conglomerate was higher,the amplitude shielding of the underlying formation,which could change the reflected energy intensity by 60%,was stronger.Finally,the two technical schemes of“increasing the lighting range”and“Q-compensated reverse time migration(Q-RTM)”technology were adopted for energy compensation of the shielding area from the perspectives of seismic acquisition and data processing,respectively,and the effectiveness of the schemes was verified in the forward modeling and the measured data.

关 键 词：底砾岩 振幅屏蔽 正演模拟 屏蔽比例 照明范围 Q-RTM 

分 类 号：P631[天文地球—地质矿产勘探]