海上地震勘探技术-基础知识探析.pptVIP

2m 8m 14m 水柱混响影响记录 CMP gather BP 40-80Hz AGC display 水深：7.8m 水深：7.2m 水深：6.3m 水深：4.8m 150Hz 150Hz 150Hz 150Hz Multiple 海底多次CDP道集记录 谢谢大家 * 小于10米误差，达到80% * Regular: surface wave, refraction, seawater wave, air wave…. Random: due to operation condition, such as wind, surf, tide etc.….. * The picture shows that shallow depth hole, over charge, and blasting inside probably record a lots high frequency noise. Using deeper hole, or reduce charge size can avoid this kind noise very well, . * From this displays, we find the high frequency noise very strong when recording in strong windy day. When it’s frequency more than 20 hz, the effective seismic single can’t be found. How to eliminate this noise in field, it is sure that the recording crew standby is best way. * As tide is rising, the ocean bottom current is very strong, we probable record such degrade seismic data. * When receive line covers the thick muddy beach, the high frequency is absorbed seriously. the left picture shows the middle part’s frequency is obvious lower than tow sides. The right is display of common offset trace, the result is same. Using long tail or downhole geophone to reduce this kind of effect. the picture show the geophone is made by BGP * According to technical specification, hydrophone should be laid out below 1.5 m water depth, if water depth is less than 1.5 meter. the geophones will don’t work well. Display shows that lots of channels don’t work. * Anchor and plummet, To handle this problem, we use all all these simple auxiliary tools, all these tools are developed by BGP. To handle this problem, we use all all these simple auxiliary tools, all these tools are developed by BGP. These different kinds of anchors and plummets are suitable to different ocean bottom. we use the anchors and plummets to fix the hydrophones to avoid the movement. And meanwhile, By this way , we can attenuate these low frequency noises produced by hydrophone movement quite well. * Usually, there