戈木错地区天然气水合物高分辨率反射地震探测技术试验

戈木错地区地处羌塘盆地中央隆起带北缘,在该区开展的区域地质调查表明结果表明,该区是天然气水合物成藏的有利地区.为了探测天然气水合物,在该地区开展了高分辨率地震反射探测技术试验,地震数据采集采用中间激发两边对称的观测系统,长排列、小道间距的接收方式,大吨位可控震源激发方式,获得了高质量的原始地震数据.在地震数据处理过程中,针对高原永冻土区的特点,进行了大量的处理参数试验,采用多种处理手段相结合的方式,获得了高信噪比的反射地震时间剖面.剖面上地震反射波组的形态清楚地反映了地下地质构造特征,依据天然气水合物成藏理论和木里地区天然气水合物表现出的频率高、振幅弱、速度低等地球物理特征,对戈木错地区天然气水合物成藏有利靶区进行了探讨和圈定.试验结果表明,高分辨率地震反射探测技术是一种非常有效的探测天然气水合物的手段,对今后在高原永冻土区开展天然气水合物地震探测有一定的借鉴作用.

Experiment on high-resolution reflection seismic exploration technique for natural gas hydrate in Gemucuo area

Gemucuo area is located on the northern margin of the central uplift belt in Qiangtang basin.The results of regional geological survey of the area show that the area is a favorable area of gas hydrate formation.In order to detect the gas hydrate,the authors carried out high resolution seismic reflection detection test in the area.High quality original seismic data were obtained in the process of seismic data acquisition by using such means as the observation system of Intermediate excitation and bilateral symmetry and the receive mode of long spread and shot trace intervals as well as the excitation mode of large tonnage vibrator.In seismic data processing,according to the characteristics of permafrost area in the plateau,the authors conducted a large number of tests for parameters,and used a combination of various means of treatment and the reflection seismic time profiles,thus obtaining high signal-to-noise ratio.The seismic reflection wave group in the seismic time profiles clearly reflects the features of subsurface geological structure.The authors investigated and delineated the favorable target area for gas hydrate accumulation in Gemucuo.The test results show that the high resolution seismic reflection detection technology is a very effective means for detection of natural gas hydrate,and hence it can serve as a reference technology for the seismic exploration of natural gas hydrates in permafrost regions in plateau in future.