山区煤田地震勘探中静校正存在的问题及其改进方法
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摘要
在山区或地表复杂地区进行地震勘探,采用基于地表一致性假设的静校正将会严重影响勘探效果,该影响主要源于地表一致性假设存在着不合理因素,如较高的低速带、巨厚的低速带、基岩裸露、地形起伏较大等。为分析一致性假设静校正偏差产生的原因及大小,构建一地形起伏、基岩出露的复杂模型,通过正演其射线路径,对比其时距曲线与理论时距曲线的差异,以及二者静校正量误差大小。模型分析证实该差异与偏移距、地震波穿透深度及基准面高程之间存在直接的联系,据此提出了改进方法,如浮动基准面校正及分块静校正等。理论模型和实际地震资料试算表明,使用改进的方法可有效改善地震时间剖面同相轴聚焦效果及连续性。
To carry out seismic prospecting in mountainous or complicated surface area,using statics based on surface consistency hypothesis will bring on serious impact to prospecting effects.The impact is mainly from unreasonable factors existed,such as higher and thicker low-velocity layer,exposed bedrock,and undulating landform etc.For analyzing statics deviation causation and extent based on surface consistency hypothesis,constructed a complicated model with undulating landform and exposed bedrock,through forward modeling of its raypath,contrasted differences between practical time-distance curves and theoretical time-distance curves,as well as statics error magnitude.The model analysis confirmed that direct relation between the differences and offset,penetration depth of seismic wave,datum plane elevation,on these grounds put forward improving methods such as floating datum plane correction and partitioning statics etc.Tentative calculation demonstrated that the modified method can effectively improve seismic section phase axis focusing effect and continuity.
To carry out seismic prospecting in mountainous or complicated surface area,using statics based on surface consistency hypothesis will bring on serious impact to prospecting effects.The impact is mainly from unreasonable factors existed,such as higher and thicker low-velocity layer,exposed bedrock,and undulating landform etc.For analyzing statics deviation causation and extent based on surface consistency hypothesis,constructed a complicated model with undulating landform and exposed bedrock,through forward modeling of its raypath,contrasted differences between practical time-distance curves and theoretical time-distance curves,as well as statics error magnitude.The model analysis confirmed that direct relation between the differences and offset,penetration depth of seismic wave,datum plane elevation,on these grounds put forward improving methods such as floating datum plane correction and partitioning statics etc.Tentative calculation demonstrated that the modified method can effectively improve seismic section phase axis focusing effect and continuity.
引文
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[2]井西利.大剩余静校正量求解的两步法[J].石油地球物理勘探,2003,38(1).
[3]李福元,赵瑞培.复杂地表地震资料的地形校正[J].石油地球物理勘探,2002,37(增刊).
[4]林依华,张中杰,尹成,等.复杂地形条件下静校正的综合寻优[J].地球物理学报,2003,46(1).
[5]王顺国.复杂山区静校正方法研究及效果[J].石油物探,1998,37(4).
[6]傅旦丹.静校正中剩余时差的拾取[J].江汉石油学院学报,1991,13(4).
[7]凌云.模型初至地表一致性静校正[J].石油地球物理勘探,1992,27(3).
[8]R.D.Wisecup等.三维采集观测系统和三维静校正的关系[J].石油物探译丛,1995,6.
[9]程金星,董敏煜,秦顺亭,等.三种算法联合迭代反演求取最佳剩余静校正量[J].地球物理学报,1996,39(3).
[10]候健全,王建立,孟小红.适合于复杂地表条件下静校正处理技术[J].物探与化探,2002,26(4).
[11]贾丽华,曾庆才,段洪友,等.塔中沙漠地区深层地震资料处理方法[J].物探与化探,2002,26(3).
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