桂中山区宽线地震采集观测系统优选

Geometry optimization for wide line seismic acquisition in Guizhong mountainous area

(中国石油化工股份有限公司油田勘探开发事业部,北京100728)

Yu Shihuan,Oilfield Exploration & Development Affairs Department,SINOPEC,Beijing 100728,China

广西中部喀斯特地貌区地表非均质性强，每一条单线的共炮点记录和共接收点记录品质在不同岩性段存在较大的不一致性，单线叠加不能很好地解决这个问题。为此，进行了3线3炮宽线地震采集试验，分别对3条单线和单线相加的共炮点记录、共接收点记录，以及单线和宽线叠加剖面的信噪比和频率进行了对比分析。结果表明，当3条单线的信噪比曲线变化趋势较为一致时，单线相加或宽线的信噪比提高幅度不大，采用宽线方式的优势不明显；当3条单线的信噪比曲线变化趋势不一致或剧烈变化时，单线相加或宽线的信噪比提高幅度较大，这种情况下采用宽线方式的优势明显。但宽线方式多线接收不可避免地降低了资料的频率成分。在此基础上，提出了利用单线信噪比最低值和主频最高值计算剖面信噪比提高率和主频降低率的方法，探讨了不同宽线方式的剖面信噪比和主频之间存在的近似反比关系，给出了近似拟合公式，据此选取桂中山区合理的宽线观测系统为3线2炮观测方式。

The surface of karst topography in Guizhong mountainous area is characterized by strong heterogeneity,so the quality of common-shot record and common-receiving record of different lithology sections in one single line varies largely,and the stack of single line cannot well solve the problem.Therefore,we carried out three-line & three-shot wide line seismic acquisition experiment,to analyze the common-shot record and common-receiving record of the sum of three single lines,as well as the S/N and frequency of single-line and wide line stack profiles.The results show that when the variation of the S/N curves from the three lines is uniform,the S/N cannot be largely improved by single-line stack or wide line,so the advantage of wide line is not obvious;if the variation trend is severe,wide line means is optimal.However,multi-line receiving in wide line means will inevitably decrease the frequency component of the seismic data.Aiming at the problem,we proposed the method for computing the improvement ratio of S/N and the reduction ratio of dominant frequency by using lowest value of S/N and highest value of dominant frequency of single line.Meanwhile,we discussed the approximate reciprocal relationship between the S/N and dominant frequency with wide line means and obtained the approximate fitting formula.In terms of the achievements,we selected three-line & two-shot wide line geometry for the seismic acquisition of Guizhong mountainous area.

10.3969/j.issn.1000-1441.2011.04.014