二维叠前深度偏移连片处理及成像建模技术
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摘要
塔里木盆地塔中地区深层低幅度构造是有利的含油气区 ,但因构造探明程度低 ,很难准确确定钻探井位 ,再加上一些地区利用二维地震资料做构造图 ,使得小幅度构造的可靠性进一步降低。为了在利用二维地震资料条件下提高深层小幅度构造的可靠性 ,进一步提高构造成像的真实性 ,提出了如下研究思路 :在时间域解决近地表静校正闭合差和提高资料信噪比 ;在深度域消除相交测线的速度闭合差 ;进行二维叠前深度偏移连片处理。基于这种思路 ,在时间域首先对每条二维测线做初至折射静校正 ,以便消除由近地表引起的剖面闭合差。然后利用二维测线按照三维叠前深度偏移方法建立全区统一的速度场 ,并从该速度场中抽取每条二维测线的叠前深度偏移速度场 ,使每条二维测线准确成像。从最终结果来看 ,新剖面较老剖面在信噪比和成像精度上有较大的提高 ,新落实的小幅度构造与井分层数据吻合较好。因此认为 ,依据所提思路和方法进行连片处理较好地解决了中深层低幅度构造的成像问题。
The small scale structure of deep layers in the central area of Tarim basin have good future in petroleum accumulation. But because the structure have lower reality, so geologist is difficult in deciding a well location. If 2 D seismic data is used for doing structure map, this make small scale structure have lower reliable. For added the reliance of small scale structure in 2 D seismic data, we give out processing idea: In time domain, static mistie and the S/N ratio of 2 D seismic data are resolved; in depth domain, the elimination of 2 D multiline velocity mistie and 2 D prestack depth migration processing are done to improve the reality of structure imagine. Based on this idea, we first do first break refraction static in order to eliminate surface effect in time domain. Then based on the idea of 3 D prestack depth migration, 3 D consistent velocity model of survey area is built by 2 D seismic data. 2 D line interval velocity model of doing prestack depth migration can be got from 3 D consistent velocity model. This method have a advantage that every line have good imagine in addition to no add new mistie. By comparing new data with old data, final imagine have great improving in the S/N ratio and imagine precision, and new small scale structure have good similar with well data. This method have partly resolved imagine problems of small scale structure.
The small scale structure of deep layers in the central area of Tarim basin have good future in petroleum accumulation. But because the structure have lower reality, so geologist is difficult in deciding a well location. If 2 D seismic data is used for doing structure map, this make small scale structure have lower reliable. For added the reliance of small scale structure in 2 D seismic data, we give out processing idea: In time domain, static mistie and the S/N ratio of 2 D seismic data are resolved; in depth domain, the elimination of 2 D multiline velocity mistie and 2 D prestack depth migration processing are done to improve the reality of structure imagine. Based on this idea, we first do first break refraction static in order to eliminate surface effect in time domain. Then based on the idea of 3 D prestack depth migration, 3 D consistent velocity model of survey area is built by 2 D seismic data. 2 D line interval velocity model of doing prestack depth migration can be got from 3 D consistent velocity model. This method have a advantage that every line have good imagine in addition to no add new mistie. By comparing new data with old data, final imagine have great improving in the S/N ratio and imagine precision, and new small scale structure have good similar with well data. This method have partly resolved imagine problems of small scale structure.
引文
1Paradigm公司.GeoDepth深度偏移软件联机用户手册.
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[1] 刘全新,李道善.关于山地静校正和偏移基准面的一些认识[J].天然气地球科学,2003,14(1):57-59.
[2] 贺振华.反射地震资料偏移处理与反演方法[M].重庆:重庆大学出版社,1989.
[3] 黄续德,袁明德,译.地震数据处理[M].北京:石油工业出版社,1994.
[4] 马在田.论反射地震偏移成像[J].勘探地球物理进展,2002,25(3):1-5
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