摘要
定标号在野外采集时同步打印在模拟剖面上,它是海洋单道地震勘探剖面对比解释时重要的地理位置依据,但是数字单道地震记录仪记录的地震道中缺失此信息.文章介绍了三种计算和标识定标号(Mark)的方法,根据班报线性内插法、模拟剖面读取法以及坐标对比法,分析了各自的优缺点.其中最可靠和实用的是坐标对比法.通过软件开发实现了坐标对比法自动获取Mark-Shot关系,通过这个关系即可对地震数据和剖面进行定标号的标识.软件模块能够处理导航与地震不同步、航向航速不稳定、导航与地震坐标格式多样化等情况,具有较强的适应性.对实测数据计算发现,当导航、地震不同步时,线性内插法获得的mark值误差很大,而坐标对比法能够精确反映Mark-Shot实际的对应关系.当航向、航速稳定时Mark-Shot关系表现为线性关系,而航向、航速不稳定时Mark-Shot关系为弯曲的非线性关系,由于导航系统过零点时会出现重复定标情况,在Mark-Shot关系图中表现为拐点.为了对计算结果进行质量控制,软件同时提供了Mark-Shot计算误差值列表,在误差散点图中显示所有定标号位置误差都小于1个炮距,说明软件计算获得的Mark位置精度较高,结果可靠.
Mark line and its number is plotted on field analog section at a certain distance such as 1km or 500m.it contains important location information for marine high resolution single-channel seismic section interpretation.According to this common location mark,seismic section could be compared with boring data,logging,sub-bottom profiler,seabed video or some other survey data.However,mark line number is not recorded in seismic data by IXSEA DELPH single-channel seismic recorder.Raw seismic data were polluted by all kinds of noise such as multiples,wave noise and vessel mechanical noise,which bring down the signal-to-noise.Raw data need to be processed to get rid of these noises.So it is necessary to compute and import the mark line number in order to plot it on the processed single-channel seismic section.Three methods for acquiring mark number were discussed.The first method is to read first and last mark number from field logs and compute midway mark number by linear interpolation.However,this method is of no use when seismic job is asynchronous with navigation.It may lead to serious error.The second method is to read mark number and shot number from field-plotted section.Its result is reliable,However,it costs too much of labor and time.The last but the best method is to match the longitude and latitude of each mark point with that of each shot point.In this way the nearest shot point for each mark point could be found and we can get some Mark-Shot pairs.A software module was developed to find the nearest shot point for each mark point automatically.According to this shot-mark pairs,mark line and its number could be imported to seismic data and marked on processed single-channel seismic section.The program works well even if seismic job is asynchronous with navigation,course or speed is changed.It can read and compare longitude and latitude value in several different unit such as degree-minute-second,degree-minute,and etc.This module has been applied to several projects in three years.Mark-Shot relation was linear when course and speed of the ship keep unchanged,or it was curved.When two or three mark line numbers be generated on the same location at zero o＇clock,an inflexion point appears on the computed Mark-Shot line which showed true abnormal Mark-Shot relations clearly.To quality control the result,the Computing error,difference between mark line location and its nearest shot point location in shot space,was output at the same time.The error values for one case line were listed and plotted.They were all less than 1 shot space,which means the computing method is of high precision and trusty.
出处
《地球物理学进展》
CSCD
北大核心
2012年第5期1871-1880,共10页
Progress in Geophysics
关键词
单道地震剖面
定标号
软件开发
计算误差
single-channel seismic section
mark line number
software program
compute error
