黄河三角洲冲积平原区地震资料低频问题剖析

Seismic data analysis of low frequency in the Yellow river delta alluvial plain

随着胜利油田勘探开发的逐步深入,对地震资料分辨率的要求也越来越高,而位于海陆过渡带的黄河三角洲冲积平原区,由于受控于海洋与河流两种环境,海岸侵蚀与河道淤积交替出现,致使近地表结构异常复杂.在义古60—义古48—义东13连井地区,地震单炮记录出现了明显的低频现象.为找到产生低频的主要原因,通过静力触探、钻孔岩芯和近地表沉积物样品分析,对激发岩性中的有机腐殖质和贝壳层、激发岩性自身的物性参数、地表环境以及近地表微地貌进行了层层剖析,从中找出了该地区产生低频是由于近地表粉砂含量较大,岩性疏松,加之旱季时蒸发量大,使得激发岩性中含水率降低造成的.研究结果对于该区后续地震采集及类似地区地震采集具有很好的借鉴意义.

With the gradual deepening exploration in Sheng-li oilfield,the resolution ratio is getting higher and higher. Zhan-hua sag is located in the land-sea transition zone,as controlled by the ocean and river environments,coastal erosion and river deposition alternated fast,resulting in complex near surface structure. In the connected wells region of YG60-YG48-YD13,seismic shot records have low-frequency phenomena. In order to know the main reason,we used cone penetration test,drill core and near surface sediment samples,to analyze various possibilities,such as organic humus and shell bed which mixed in the lithology,physical parameters,surface environment and micro topography. Finally,we found out the cause of the low-frequency. That is the large silt content, the loose lithology,and the large evaporation during dry season,which results in the decrease of the water content in the shooting lithology. The result of the study is a good reference for follow-up work and similar areas seismic acquisition.