对镇巴复杂山地地震采集的思考
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摘要
镇巴区块的区域构造位置属于四川盆地东北部的大巴山台缘断褶带,为盆山耦合的复杂区带,地形、地貌极其复杂,地表山峦叠嶂,沟壑纵横,且山高谷深,地形最大相对高差达千米以上,具有国内外山地地震勘探罕见的复杂地貌条件。其构造类型主要为断层相关褶皱、叠瓦状构造及断层三角带。现有的二维地震资料具有信噪比低、构造成像差的特点。本文针对影响地震资料采集质量的各种因素,就如何提高地震采集质量进行了细致分析和思考,得到了一些初浅的认识。认为应当在充分进行地质调查、表层结构调查、干扰波调查的基础上,针对工区表层地质特点,借助于观测系统优化设计技术,开展小道距、高覆盖次数、超多道、大排列分区、分线、分段变观测量和野外观测方法试验研究,以及广角地震采集、处理方法和应用效果研究。同时,开展山地表层吸收衰减特性的野外调查和理论分析,并借助于地震波正演模拟以及地质研究等对地震波传播的波场特征进行分析,总结规律,积累经验,为进一步的野外生产提供指导。
The regional structural position of Zhenbe block belongs to fault-fold zone of Dabashan platform edge, the northeast of Sichuan basin, which is basin-to-mountain-coupled complex zone that is characteristics of complex geomorphy, peaks rising falling heavily, criss-cross gully, and higher mountains and deep valleys that relative elevation difference can reach several thousand km and above, which is complex geomorphic condition seldom seen in mountainous seismic exploration at home and abroad. The structural types mainly are fault-related folds, imbricate structure and fault delta zone. The available 2D seismic data were characterized by lower S/N ratio and poorer structural imaging. According to the various factors affecting the acquired quality of seismic data, we conducted the analysis in detail and thought how to improve the seismic acquisition quality and gained preliminary knowledge. We considered on the basis of full geologic investigation, surface structure survey and interference waves investigation, it should carry out test and experiments about small group interval, higher folds, ultra-multiple receiver, larger spread, geometry-changed survey by separate blocks, lines and segments and other field surveying methods in view of geologic feature of surface layers in work area and by the aid of optimal geometry designing technique as well as study of wide-angle seismic acquisition, processing and application. At the same time, it should develop field investigation and theoretical study about mountainous near-surface attenuation by absorption; the study of wavefield feature of seismic wave propagation should also be carried out by the aid of seismic wave forward simulation and geologic study, which summarizes the regularity and accumulates the experiences, providing guide for next field production.
The regional structural position of Zhenbe block belongs to fault-fold zone of Dabashan platform edge, the northeast of Sichuan basin, which is basin-to-mountain-coupled complex zone that is characteristics of complex geomorphy, peaks rising falling heavily, criss-cross gully, and higher mountains and deep valleys that relative elevation difference can reach several thousand km and above, which is complex geomorphic condition seldom seen in mountainous seismic exploration at home and abroad. The structural types mainly are fault-related folds, imbricate structure and fault delta zone. The available 2D seismic data were characterized by lower S/N ratio and poorer structural imaging. According to the various factors affecting the acquired quality of seismic data, we conducted the analysis in detail and thought how to improve the seismic acquisition quality and gained preliminary knowledge. We considered on the basis of full geologic investigation, surface structure survey and interference waves investigation, it should carry out test and experiments about small group interval, higher folds, ultra-multiple receiver, larger spread, geometry-changed survey by separate blocks, lines and segments and other field surveying methods in view of geologic feature of surface layers in work area and by the aid of optimal geometry designing technique as well as study of wide-angle seismic acquisition, processing and application. At the same time, it should develop field investigation and theoretical study about mountainous near-surface attenuation by absorption; the study of wavefield feature of seismic wave propagation should also be carried out by the aid of seismic wave forward simulation and geologic study, which summarizes the regularity and accumulates the experiences, providing guide for next field production.
引文
[1]云美厚等.镇巴复杂山地地震采集质量影响因素分析.石油物探,2006,45(5)(待发)
[2]苟量等.西部复杂山地地震勘探走势分析.石油地球物理勘探,2005,40(2):248~251
[3]杨凯.沙漠地区低降速带地震波的传播特征与衰减补偿方法研究[博士学位论文].同济大学海洋与地球科学学院,2004
[4]唐成鸽等.塔中沙漠地区石油地震勘探数据采集技术.勘探地球物理进展,2004,27(6):407~414
[5]王志等.高速屏蔽层下弱反射层地震勘探——广角反射.勘探地球物理进展,2002,25(5):407~414
[6]Richard Wet al.Long offset acquisition and processing for sub-basalt i maging.Expanded Abstracts of69th SEG Mtg,1999
[7]邓志文.高陡逆掩推覆构造地区地震观测系统研究.石油物探,2002,41(2):127~131
[2]苟量等.西部复杂山地地震勘探走势分析.石油地球物理勘探,2005,40(2):248~251
[3]杨凯.沙漠地区低降速带地震波的传播特征与衰减补偿方法研究[博士学位论文].同济大学海洋与地球科学学院,2004
[4]唐成鸽等.塔中沙漠地区石油地震勘探数据采集技术.勘探地球物理进展,2004,27(6):407~414
[5]王志等.高速屏蔽层下弱反射层地震勘探——广角反射.勘探地球物理进展,2002,25(5):407~414
[6]Richard Wet al.Long offset acquisition and processing for sub-basalt i maging.Expanded Abstracts of69th SEG Mtg,1999
[7]邓志文.高陡逆掩推覆构造地区地震观测系统研究.石油物探,2002,41(2):127~131
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