Low‐frequency microtremor anomalies at an oil and gas field in Voitsdorf, Austria
Low‐frequency microtremor anomalies at an oil and gas field in Voitsdorf, Austria
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DOI：
10.1111/j.1365-2478.2008.00734.x
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发表时间：
2009-05
影响因子：
2.6
通讯作者：
M. Lambert;S. Schmalholz;E. Saenger;B. Steiner
中科院分区：
文献类型：
--
作者：
M. Lambert;S. Schmalholz;E. Saenger;B. Steiner
本文介绍了奥地利Voitsdorf油气田被动地脉动测量的结果。该调查包括两个油气藏上约9公里长的六个平行剖面。对于每个剖面，在11个在线台站同步记录地震波场。测量是用宽带地震仪进行的，每个剖面至少持续12个小时。数据解释是以综合数据集和对四种不同光谱属性的分析为基础的。这些属性量化了低频范围（<10Hz）内波场傅立叶频谱的特征。一个属性量化垂直波场分量中的谱能量，另一个属性量化垂直与水平谱比中的最大值，并且两个属性描述垂直和水平波场分量的谱内的峰的频率偏移。由于信号的时间变化，我们联合收割机将多个剖面的长期测量（几个小时的连续记录）结合起来。这个过程大大提高了每个光谱属性的一致性，使它们适合量化波场的横向变化。结果表明，使用几个属性的组合显着增加的可靠性，检测异常的微动波场，推测是由油气藏。应用二维地震波传播的数值研究来调查峰值频移属性。研究结果表明，假设储层作为低频地震波的（次级）震源，属性可能包含有关油气藏深度的信息。
Results of a passive microtremor survey at an oil and gas field in Voitsdorf, Austria, are presented. The survey consists in six parallel profiles approximately 9 km long over two hydrocarbon reservoirs. For each profile the seismic wavefield was recorded synchronously at 11 in‐line stations. The measurements were conducted with broadband seismometers and lasted, for each profile, at least 12 hours overnight. Data interpretation is based on a comprehensive data set and on the analysis of four different spectral attributes. These attributes quantify the characteristic features of the wavefield's Fourier spectra in the low‐frequency range (<10Hz). One attribute quantifies the spectral energy in the vertical wavefield component, another attribute quantifies the maxima in vertical‐to‐horizontal spectral ratios and two attributes describe the frequency shifts of peaks within the spectra of vertical and horizontal wavefield components. Due to temporal variations of the signals we combine the long‐term measurements (several hours of continuous records) of multiple profiles. This procedure considerably enhances the consistency of each spectral attribute and makes them suitable to quantify lateral variations of the wavefield. The results show that using a combination of several attributes significantly increases the reliability of detecting anomalies in the microtremor wavefield that are presumably caused by hydrocarbon reservoirs. A numerical study of two‐dimensional seismic wave propagation is applied to investigate the peak frequency shift attributes. The results of the study indicate that the attributes may contain information on the depth of hydrocarbon reservoirs, assuming that the reservoir acts as a (secondary) source of low‐frequency seismic waves.