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我国陆域天然气水合物主要分布于青藏高原和漠河地区.由于永久冻土层的存在,地震勘探很难获得高品质的资料,给天然气水合物勘探带来了诸多困难.为解决冻土层对地震信号的衰减问题,在哈拉湖地区采用低频可控震源进行地震资料采集试验,通过提高覆盖次数,获得了较高信噪比的地震资料.在高质量地震资料基础上,进行精细速度分析,获得了较准确的叠加速度谱资料;然后以层速度剖面为基础建立正演模型,开展天然气水合物地震正演模拟研究;最后利用叠后偏移地震数据进行地震属性分析.通过正演模拟和地震属性综合研究,总结了天然气水合物的地球物理响应特征,速度突变和空白反射带可作为哈拉湖地区陆域天然气水合物识别的敏感因素.
China’s terrestrial gas hydrates are mainly distributed in the Qinghai-Tibet Plateau and the Mohe area.Seismic exploration is difficult to obtain high-quality data because of the permafrost, which brings many difficulties to the exploration of gas hydrate. Seismic signal attenuation problem in the Hala Lake region using low-frequency vibroseis for seismic data acquisition test, by increasing the number of coverage, access to a high signal-to-noise ratio of seismic data.On the basis of high-quality seismic data, the fine velocity analysis , And obtained more accurate superimposed velocity spectrum data. Then, based on the layer velocity profile, a forward model was established to study the forward modeling of natural gas hydrate seismic data. Finally, the seismic attribute analysis of post-migration offset seismic data was carried out. Through forward modeling And seismic attributes, the geophysical response characteristics of natural gas hydrate are summarized. The abrupt change of velocity and blank reflection band can be used as sensitive factors for the recognition of the natural gas hydrate in Hala Lake region.