微地震台阵网天然地震层析成像技术在油田深层构造解析中的应用
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摘要
天然地震层析成像相对于传统的反射地震方法而言是一种新的经济的勘探方法。这是由于天然地震层析成像所需的观测值直接来自于研究区下方发生的天然微地震,而反射地震却需要在研究区表面进行人工放炮。因此本工作是将天然地震层析成像方法应用于柴达木盆地西部某油田约100km2地区的深层构造的尝试性研究。626个地震事件的3289个P波到时的初步结果与研究区已知的大的构造吻合较好。该模型中非常显著的特征就是观测到一个北西向的背斜。此外,微地震的分布也与研究区中活动断裂带的位置基本一致。
Passive seismic tomographic imaging is a new and economical exploration method as compared to the traditional seismic reflection method because passive seismic tomographic imaging only needs observations directly from micro-earthquakes occurring underneath the study area, while the reflection method needs firing shots at the surface. So this work is an attempt to use the passive seismic tomographic imaging technique to study deep tectonics beneath an area of ～100 km2 in an oilfield in the western Qaidam basin. The preliminary results based on a total of 3289 P-wave arrival times of 626 seismic events show good coincidence with the known large tectonics of the study area. A very striking feature imaged by the proposed model is a NW-trending large anticline. In addition, the micro-earthquakes are also in the main located along the active fault belt.
Passive seismic tomographic imaging is a new and economical exploration method as compared to the traditional seismic reflection method because passive seismic tomographic imaging only needs observations directly from micro-earthquakes occurring underneath the study area, while the reflection method needs firing shots at the surface. So this work is an attempt to use the passive seismic tomographic imaging technique to study deep tectonics beneath an area of ～100 km2 in an oilfield in the western Qaidam basin. The preliminary results based on a total of 3289 P-wave arrival times of 626 seismic events show good coincidence with the known large tectonics of the study area. A very striking feature imaged by the proposed model is a NW-trending large anticline. In addition, the micro-earthquakes are also in the main located along the active fault belt.
引文
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[2]Kosarev G,Kind R,Sobolev S V,et al.Seismic evidence for a detached Indian lithospheric mantle beneath Tibet[J].Science,1999,283:5406,1306-109.
[3]Zhao D P,Kayal J R.Impact of seismic tomography on earth sciences,special section:seismology2000[J].Current Science,2000,79(9):1208-1214.
[4]史大年,吕庆田,徐明才,等.铜陵矿集区地壳浅表结构的地震层析研究[J].矿产地质,2004,23(3):383-389.
[5]Aki K,Christoffersson A,Husebye E S,et al.Three-dimen-sional seismic-velocity anomalies in the crust and upper-mantle under the U.S.G.S.California seismic array(abstract)[J].EOS Trans.AGU,1974,56:1145.
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