两步法地震深度成像技术及其应用效果
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摘要
在地震资料信噪比较高的地区,采用叠前深度偏移技术获得的深度剖面,可较好地反映实际构造形态。但在地震资料信噪比低的山地复杂构造区,叠前深度偏移处理周期长,成像普遍较差,难以满足构造地质研究和油气勘探发展的需求。两步法地震深度成像是一种快速准确的成像方法。第一步在时间域里归位,采用叠后时间偏移或叠前时间偏移,对叠加剖面上的横向畸变现象(回转波、绕射波、断面波及倾斜反射波)进行偏移。第二步在深度域里归位,在偏移时间剖面上,建立有井约束层速度模型,通过变速时深转换,实现纵向归位,纵向上消除受速度"上拉效应"形成的假背斜和假高点,最终获得能真实反映地下构造形态的深度剖面。该项技术已在复杂油气田勘探开发中得到广泛应用,并取得良好的应用效果。
Adoption of pre-stack depth migration technology for depth cross-section in a region where the seismic data S/N ratio is high can satisfactorily reflects the pattern of actual structure. However, in a mountainous complicated structural region where the seismic S/N ratio is low, pre-stack depth migration processing is difficult to meet the requirements for geological study of structure and development of oil and gas exploration because of a long period and a poor imaging quality. Two-step seismic depth imaging is a rapid and precise imaging method. The first step is migration in time domain, adopting post-stack time migration or pre-stack time migration to migrate the lateral distortion phenomena on the stack cross-section (such as bow-tie, diffraction, fault plane reflection and dipping reflection). The second step is migration in depth domain, vertically eliminating false anticline or false structure high caused by velocity "pull-up effect" and finally acquiring the really-reflected depth profile of underground structure. This technology has been extensively used in exploration and development of complicated oil and gas fields with good application results achieved.
Adoption of pre-stack depth migration technology for depth cross-section in a region where the seismic data S/N ratio is high can satisfactorily reflects the pattern of actual structure. However, in a mountainous complicated structural region where the seismic S/N ratio is low, pre-stack depth migration processing is difficult to meet the requirements for geological study of structure and development of oil and gas exploration because of a long period and a poor imaging quality. Two-step seismic depth imaging is a rapid and precise imaging method. The first step is migration in time domain, adopting post-stack time migration or pre-stack time migration to migrate the lateral distortion phenomena on the stack cross-section (such as bow-tie, diffraction, fault plane reflection and dipping reflection). The second step is migration in depth domain, vertically eliminating false anticline or false structure high caused by velocity "pull-up effect" and finally acquiring the really-reflected depth profile of underground structure. This technology has been extensively used in exploration and development of complicated oil and gas fields with good application results achieved.
引文
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[10]陆基孟.地震勘探原理[M].北京:石油工业出版社,1982:212～247.
[2]梁顺军,肖宇,刁永波,等.库车坳陷山地复杂构造速度场研究及其应用效果[J].中国石油勘探,2011,16(4):59～64.
[3]宁宏晓,胡杰,章多荣,等.柴达木英雄岭复杂山地三维地震勘探技术[J].石油科技论坛,2012,31(2):2～6.
[4]梁顺军,肖宇.库车坳陷西秋构造带盐下低幅度构造圈闭研究及勘探思路[J].中国石油勘探,2012,17(1):19～24.
[5]梁向豪,周旭,蔡明,等.复杂山地高密度宽线地震采集技术及应用效果[J].西南石油大学学报:自然科学版,2012,34(4):69～74.
[6]吴希光,李亚林,张孟,等.复杂地区地震资料低信噪比的原因及对策(一)——表层散射波是导致地震资料低信噪比的根本原因[J].天然气工业,32(1):27～32.
[7]梁向豪,李书君,吴超,等.库车大北构造带三维叠前深度偏移处理解释技术[J].中国石油勘探,2011,16(5-6):8～13.
[8]梁顺军,彭更新,齐英敏,等.山地复杂构造地震成图方法探讨[J].石油物探,2003,42(4):529～537.
[9]梁顺军,梁顺彬.高陡背斜地震剖面高点偏离问题分析及其校正[J].石油地球物理勘探,2001,36(1):105～114.
[10]陆基孟.地震勘探原理[M].北京:石油工业出版社,1982:212～247.
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