哈拉湖地区天然气水合物地震探测技术试验

哈拉湖位于青藏高原,在该区开展的地质调查、音频大地电磁测深和地球化学调查结果表明,该区具有良好的天然气水合物找矿前景。为寻找天然气水合物,在该区开展了高精度反射地震试验。反射地震采用1200道接收,道间距2 m,偏移距1 m,炮间距8 m,覆盖次数150次,排列中间激发的观测系统,每道采用6个60 Hz检波器单点组合接收;采样间隔0.5 ms,记录长度2 s,宽频带采集;激发震源为大型车载可控震源。采用该工作方法得到的地震剖面信噪比和分辨率较高,构造形态特征明显。根据试验区地形地貌和地震剖面上反映的永冻土层厚度、断裂构造和高速层分布,结合其他资料,确定了验证孔位。

Experiment on seismic exploration technique of natural gas hydrate in Halahu area

Halahu is located in the Tibetan Plateau.The results of geological survey,AMT (Audio Magnetotelluric Sounding) and geo?chemical survey show that there is good perspective of natural gas hydrate prospecting in this area.High?precision seismic reflection ex?periments were carried out in search for natural gas hydrate in the area.1 200 receiving channels,2 m group spacing,1 m offset,8 m shot spacing,150 folds,the surveillance system excited in spread middle were used in reflection seismic survey.60 Hz geophone string ( with 6 geophones) was adopted,each received channel receiving seismic wave in the form of point array.Excitation source was large vehicle?borne Vibroseis.Instrument recording factors used included 0.5 ms sampling,2 s recording length and whole-band receiving.The high S/N ratio and resolution as well as obvious structural form characteristics were provided with seismic section obtained by the method.Vali?date hole location was determined according to land feature and the permafrost thickness,fault structure and high-speed distribution re?flected on seismic profile as well as other data.