六种岩性海底地震波透射能量AVA特征研究
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摘要
海上地震勘探中的海底透射波能量分布特征影响勘探方案设计和数据处理。针对此问题,基于流—固界面反射和透射系数及能量方程等理论,探讨了淤泥、凝灰岩、粉砂岩、粗砂岩、石灰岩和花岗岩等六种岩性海底的透射波能量随入射角的变化特征。研究结果表明,随着入射角变化,不同岩性海底的透射波能量分布差异很大:①淤泥,小于临界角(49°)时有利于透射纵波勘探,大于临界角时有利于透射转换波勘探;②凝灰岩,入射角≤65°时有利于透射纵波勘探,入射角在40°~80°范围时,有利于透射转换波勘探;③粉砂岩和粗砂岩,在小于临界角(分别为61°~55°)时,有利于透射纵波勘探;④石灰岩和花岗岩,透射纵波能量在小于第一临界角(分别约为14°和18°)时为10%~30%;透射横波在第一临界角(同上)和第二临界角(分别约为28°和34°)之间约为40%,大于第二临界角后透射波消失,故此类岩性不利于海上勘探。
Energy distribution of transmitted compression wave at seafloor has an influence upon exploration scheme design and data processing.As for this issue,this paper discusses variation characteristics of transmitted wave energy of 6 types of seafloor with different lithologies(silt,tuff,powder-grained sandstone,coarse-grained sandstone,limestone and granite) with respect to the incident angle,which is based on theories like coefficients of liquid-solid interface and energy function.The situations of transmitted wave energy distribution turn out with great differences in terms of different seafloors and the same conditions of acquisition: 1) For sea-floor of silt,it is beneficial for transmitted compression wave exploration when incident angle does not go over the critical angle(49°),otherwise transmitted converted-wave exploration is more effective.2) For sea-floor of tuff,it is beneficial for transmitted compression wave exploration when incident angle is not bigger than 65°,while transmitted converted-wave exploration is more effective when incident angle is between 40° and 80°.3) For sea-floor of powder-grained sandstone and coarse-grained sandstone,it is beneficial for transmitted compression wave exploration when incident angle does not go over the critical angle(powder-grained sandstone 61°,coarse-grained sandstone 55°).4) For sea-floor of limestone and granite,10%~30% of the energy is distributed to transmitted compression wave when incident angle is smaller than the first critical angle(limestone 14°,granite 18°),while transmitted converted wave takes nearly 40% of the energy when incident angle is between the first and the second critical angle(limestone 28°,granite 34°).The transmitted wave disappears after the second critical angle.This type of seafloor is not beneficial for exploration.
Energy distribution of transmitted compression wave at seafloor has an influence upon exploration scheme design and data processing.As for this issue,this paper discusses variation characteristics of transmitted wave energy of 6 types of seafloor with different lithologies(silt,tuff,powder-grained sandstone,coarse-grained sandstone,limestone and granite) with respect to the incident angle,which is based on theories like coefficients of liquid-solid interface and energy function.The situations of transmitted wave energy distribution turn out with great differences in terms of different seafloors and the same conditions of acquisition: 1) For sea-floor of silt,it is beneficial for transmitted compression wave exploration when incident angle does not go over the critical angle(49°),otherwise transmitted converted-wave exploration is more effective.2) For sea-floor of tuff,it is beneficial for transmitted compression wave exploration when incident angle is not bigger than 65°,while transmitted converted-wave exploration is more effective when incident angle is between 40° and 80°.3) For sea-floor of powder-grained sandstone and coarse-grained sandstone,it is beneficial for transmitted compression wave exploration when incident angle does not go over the critical angle(powder-grained sandstone 61°,coarse-grained sandstone 55°).4) For sea-floor of limestone and granite,10%~30% of the energy is distributed to transmitted compression wave when incident angle is smaller than the first critical angle(limestone 14°,granite 18°),while transmitted converted wave takes nearly 40% of the energy when incident angle is between the first and the second critical angle(limestone 28°,granite 34°).The transmitted wave disappears after the second critical angle.This type of seafloor is not beneficial for exploration.
引文
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[3]R.E.谢里夫.勘探地震学.第二版,北京:石油工业出版社,1999
[4]朱光明,吴律,许云.地球物理储层参数提取.陕西西安:陕西科学技术出版社,1996
[5]W伊文著;刘光鼎译.层状介质中的弹性波.北京:科学出版社,1966
[6]布列霍夫斯基赫著.分层介质中的波.北京:科学出版社,1985
[7]赵鸿儒,唐文榜.超声地震模型试验技术及应用.北京:石油工业出版社,1984
[8]顾家伟,王张华等.东海外陆架浅孔沉积物的岩性和磁性特征及成因讨论.古地理学报,2006,8(5):269~276Gu Jia-wei,Wang Zhang-hua et al.Lithologic andmagnetic characteristics and origin of shallowbore sed-i ments on outer continental shelf of East China Sea.Journal of Palaeogeography,2006,8(5):269~276
[9]托鲁基安等著;单家增等译.岩石与矿物的物理性质.北京:石油工业出版社,1990
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