论非零偏移距VSP观测系统设计  

On the design of non-zero offset VSP layout,

作　　者：陈信平[1] 

机构地区：[1]海洋石油勘探开发研究中心

出　　处：《石油地球物理勘探》1989年第1期43-54,118,共13页Oil Geophysical Prospecting

摘　　要：观测系统的设计是非零偏移距VSP技术应用成败的关键。射线照射的“亮区”范围和反射点密度又是决定观测系统设计的两个重要因素。不合理的设计可能导致非常有限的“亮区”和反射点分布极不均匀,从而使得研究目标处于射线照亮范围之外,或者成像不清。本文分别讨论了固定偏移距VSP(OVSP),同时移动震源和检波器的VSP(MVSP)和移动震源VSP(WVSP)三种观测系统条件下,影响射线照射“亮区”范围和反射点密度的因素。在此基础上,提出了设计合理的VSP观测系统应当达到的基本要求:井下检波器间距应满足空间采样定理;震源—井口的连线应垂直于主要目的层的走向;避免大倾角入射;使研究目标落入射线照射的亮区;并获得尽可能均匀的反射点密度。文中最后列举了设计非零偏移距VSP观测系统应当遵循的一般工作程序。The key to successful or failing use of non-zero offset VSP technique lies in the design of the layout.'Ray illumination extent' and reflecting point density are the important factors that must be considered in layout design.The unreasonable design may result in very limited 'ray illumination extent' and extremely nonuniform distribution of reflecting points so that research object is outside the 'ray' illumination extent', or image is obscure.The factors are discussed which influence 'ray illumination extent' and reflecting point density in three layout cases: fixed-offset VSP, source-geophone moving VSP and walkaway VSP. The requirements for designing reasonable VSP layout are: ·downhole geophone gap satisfies sampling theorem; ·the line from source to well is normal to the strike of important target stratum; ·big-dip incidence is avoided; ·the research target is inside 'ray illumination extent'; ·reflecting points are as uniform as possible. The usual work procedure that we should follow in designing nonzero offset VSP layout are listed finally.

关 键 词：观测系统设计 偏移距 VSP 反射点 井下检波器 射线追踪 地下构造 震源位置 资料处理 克希霍夫积分法 

分 类 号：TE13[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]