海洋三维VC观测系统优化设计  

Geometry Optimization Design of Three Dimensional Marine Vertical Cable

作　　者：安振芳 张进[1,2] 张建中[1,2] 

机构地区：[1]海底科学与探测技术教育部重点实验室,山东青岛266100 [2]中国海洋大学海洋地球科学学院,山东青岛266100

出　　处：《吉林大学学报（地球科学版）》2018年第1期271-284,共14页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(41230318)~~

摘　　要：观测系统设计在地震勘探中起着至关重要的作用,最佳观测系统不仅可以提高资料品质,还能够降低采集成本。通过对海洋垂直缆(vertical cable,VC)进行正演模拟我们发现,随着偏移距的增大,同相轴会出现交叉、合并现象,地层顺序也会发生变化。我们针对单VC和多VC的特点,分别设计了相应的观测系统。然后对所设计的观测系统进行评价与优化,并得出了一些有益的结论:采用增加激发点密度的方法对面元覆盖次数的改善效果要好于采用增加激发面积的方法对面元覆盖次数的改善效果;当目标层存在倾角时,通过在构造走向上增加激发线条数,同时在下倾方向上增加激发线长度可以补偿照明损失;当目标层为背斜或向斜时,通过增大最大环半径来增加背斜和向斜照明范围的方法奏效甚微;当激发面积和接收面积相等时,通过同时增大激发面积和接收面积来提高中心区域面元覆盖次数的方法行不通,而当激发面积大于接收面积时则该问题得以解决。Geometry design plays an important part in seismic exploration.Optimum geometry can not only improve the quality of datum but also reduce the cost of acquisition.Through the forward modeling,with the increase of offset we found the phenomenon that the events would cross or even merge,and the stratigraphic sequence would become confused.According to the characteristics of a single vertical cable and multiple vertical cables,we designed the corresponding geometries,and then evaluated and optimized the designed geometries.The conclusions are drawn as follows：First,to increase shot point density is better than to increase shot area to improve bin fold;when a shot line interval is equal to a shot point interval,the distribution uniformity of a bin fold in each bin is the best.Second,when the target layer is inclined,the illumination area shows the shape of trapezoid,and part of the area can’t be illuminated.The illumination loss can be compensated through increasing the number of shot line along the structural trend,and increasing the length of shot line along the downdip direction at the same time.Third,when the target layer is anticline or syncline,to increase the scope of illumination by increasing the radius of the maximum ring is small,although the marine vertical cable is moved every where.The best way is to deploy multiple marine vertical cable in a ring.Fourth,when a shot area is equal to a receiver area,to improve bin fold of the center area by increasing both of them doesn’t work.However,it works thoroughly when the shot area is bigger than the receiver area.

关 键 词：垂直缆 观测系统 面元覆盖 照明分析 正演模拟 天然气水合物 海洋三维地震勘探 

分 类 号：P631[天文地球—地质矿产勘探]