低速带吸收补偿提高地震资料分辨率

发布时间：2018-10-20 16:50

【摘要】：地震波在近地表疏松介质中传播时,会产生强烈的吸收效应,降低了地震记录的分辨率。在大港油田进行了近地表吸收结构调查现场试验,尝试通过品质因子Q补偿消除低速带吸收对地震资料分辨率的影响。首先利用上行波微测井确定低速带的厚度和速度,再利用双井微测井观测和估算低速带的Q因子。具体步骤为:布设2口水平间隔为6 m的激发井和接收井,接收井井深3 m,与该地区低速带厚度相当,井口和井底分别埋置一个检波器。在激发井的16 m和20 m深度分别进行震源激发,在接收井的井口和井底接收直达波地震信号。利用谱比法对地震波的衰减进行了分析,在100~400 Hz频带范围内,地震衰减呈现明显的非线性特征,显示了Q对频率的依赖性。通过对衰减曲线进行非线性拟合,估算了频率依赖的Q因子,再采用反Q滤波消除了低速带吸收对地震数据分辨率的影响。
[Abstract]:When the seismic wave propagates in the loose medium near the surface, it will produce strong absorption effect, which reduces the resolution of the seismic record. The field test of near-surface absorption structure investigation was carried out in Dagang Oilfield in order to eliminate the influence of low-speed band absorption on seismic data resolution by quality factor Q compensation. First, the thickness and velocity of low velocity zone are determined by uplink micrologging, then the Q factor of low velocity zone is observed and estimated by dual well micrologging. The concrete steps are as follows: two excitation wells and receiving wells with a horizontal interval of 6 m are set up, and the depth of the receiving wells is 3 m, which is equivalent to the thickness of the low speed zone in this area, and a geophone is buried at the well head and bottom hole respectively. The source excitation is carried out at the depth of 16 m and 20 m of the excitation well, and the direct wave seismic signal is received at the well head and bottom of the receiving well. Spectral ratio method is used to analyze the attenuation of seismic waves. In the frequency band of 100 ~ 400 Hz, seismic attenuation shows obvious nonlinear characteristics, showing the dependence of Q on frequency. By nonlinear fitting of attenuation curve, the frequency dependent Q factor is estimated, and the influence of low speed band absorption on seismic data resolution is eliminated by inverse Q filter.
【作者单位】：中国石油大学油气资源与勘探国家重点实验室;中国石油大港油田公司;
【基金】：国家自然科学基金项目(No.41474109) 国家重点基础研究发展计划(973)项目(2013CB228606)资助
【分类号】：P631.4

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