宽方位三维三分量地震资料采集观测系统设计——以新场气田三维三分量勘探为例

宽方位三维三分量勘探综合了宽方位纵波勘探和转换波勘探二者的优势，对于解决川西深层致密裂缝性气藏的勘探开发问题具有良好的应用前景。而宽方位三维三分量地震采集设计是三维转换波地震勘探在技术合理、经济可行的条件下，采集到高质量多分量原始资料的技术保障。为此，首先根据储层埋藏深、岩性致密的特点，结合地质任务要求，分析了宽方位三维三分量观测系统设计的难点；然后通过观测系统参数的分析论证，确定了同时适合纵波勘探和转换波勘探的面元尺寸、最大和最小炮检距、接收线距、束间滚动距等；通过针对目的层深度和纵、横波速度比的观测系统模板分析，确定了观测系统的类型。基于上述分析设计了3种观测系统方案，通过对3种方案观测系统的玫瑰图、CMP面元和CCP面元属性、最大炮检距分布等的分析，确定了适合新场地区的宽方位三维三分量观测系统，并利用正演模拟对其进行了验证。将该观测系统应用于实际地震资料采集，获得的三分量资料波组特征清楚，同相轴连续性好，反射信息丰富；PP波剖面和PS波剖面反射层次清楚，目的层反射特征明显，构造形态一致性好。

Design of wide-azimuth 3D3C seismic data acquisition geometry-Case study of 3D3C exploration in Xinchang gas field

The wide-azimuth 3D3C seismic exploration takes the advanta- ges of both wide-azimuth P-wave exploration and converted-wave exploration.This technique can be well applied to solve the explo- ration problem of deep-buried compact fracture gas reservoirs in western Sichuan.In 3D converted-wave exploration,the design of 3D3C seismic acquisition geometry is the technical support to ac- quire high-quality multi-component original data under the condi- tion of reasonable technique and feasible economic results.There- fore,according to the characteristics of deep-buried and tight li- thology,combined with the geological requirement,difficulties for designing 3D3C geometry were analyzed.Then,through analyzing and demonstrating geometry parameters,some parameters fit for P-wave exploration and converted-wave exploration were defined, such as the bin size,the maximum and minimum offsets,the re- ceiver line distance,the swath rolling distanee etc.By analyzing geometry templates on target depth and VP/VS,the geometry was confirmed.Based on all the analyses,three geometries were de- signed.After analyzing their rose plots,CMP and CCP bin attrib- utes,maximum offset distribution,geometry suitable for Xinchang area were set and verified by forward simulation.The acquired 3D3C data based on this geometry have clear and continuous events and abundant reflection information.There are clear reflection ima- ging,obvious reflection characteristics for the target and good con- sistency in structure form for both the PP wave section and the PS wave section.