井间地震反射波速度分析及成像  

Velocity analysis and imaging of reflection wave in crosswell seismics

作　　者：张汝杰[1] 贺振华[1] 周兴元 

机构地区：[1]成都理工学院,成都610059 [2]涿州物探局研究院,涿州072751

出　　处：《石油物探》1997年第3期1-12,共12页Geophysical Prospecting For Petroleum

摘　　要：在地层物性参数完全未知的情况下，如何利用反射波信号提取速度参数，是反射波能否正确成像的前提。由于井间地震方法特殊的观测系统，给速度参数的求取带来很大的困难。为此，本文在分析了井间地震反射波叠加速度概念和误差规律的基础上，提出了近似叠加速度的概念。该速度的求取方法有两种：第一种是采用同地面地震常速扫描相似的方法拾取to—叠加速度对，这种方法简单、准确，但比较费时；另一种方法是用插值加相关的方法求取叠加速度谱。该速度谱同时考虑了速度、深度、地层倾角三个因素的影响，对于平层和单斜层都能较好地确定t0—叠加速度对。本文讨论了井间地震反射波成像的方法原理及存在的问题，提出了反射波绕射成像方法，即利用上面所述的方法求取的to—叠加速度对，对输入的共炮点道集（CSG）或共接收点道集（CRG）的每一条记录做水平动校和垂直动校，把数据从Ω（Zs，Zg，t）域映射到（x，to）域，形成to叠加剖面。该剖面既能反映排列之间地层的形态，也能反映排列之上和之下地层的变化情况。On the condition that formation physical parameters are unknown, how to extract velocity parametere from reflection waves is a premise for correct imaging of reflection waves. Because of the special observtion system for crosswell seismic methods, the determination of velocity parameters is difficult.Therefore, based on the analysis of the stack velocity concept and the error law in crosswell seismic reflection wave, we put forward a concept—approximate stack velocity. There are two methods to solvethe velority. One method is similar to the constant velocity scanning in surface seismics. It is simple andaccurate, but it is time-consuming. The other method computes the stack velocity spectra through theinterpolation plus correlation. In the spectra, three factors of velority, depth and stratigraphic dip aretaken into account. It can well determine to-υrms for beth flat layers and single dipping layers.In the paper, we discuss the principle of crosswell seismic reflection wave imaging and existingproblems, and propose a method for reflection wave diffraction imaging. By using the to-υrms information, we make horizontal normal moveout and vertical normal moveout corrections for each trace in common-shot gathers (CSG) and common-receiver gathers (CRG). The data are then mapped from Ω (Zs,Zg, t ) domain to Ω (x, to ) domain, producing to stack section. The section can display the formationshape between arrays, as well as that below and above then.

关 键 词：井间地震 绕射成像 反射波 速度分析 地震测井 

分 类 号：P631.815[天文地球—地质矿产勘探]