面向海域水合物精细刻画的地震勘探技术--耙缆式地震勘探

Novel seismic exploration technique targeting fine characterization of marine gas hydrates: seismic exploration with a harrow-like acquisition geometry

随着海域天然气水合物试采取得成功,水合物产业化开发的计划也提上了日程.水合物的开发需要更为精细的储层刻画及评价结果,这就要求更高分辨率的地震数据.水合物储层具有埋藏浅,非均匀,厚度薄等特点,目前的地震勘探技术难以满足水合物精细刻画的需求.在充分考虑现有地震技术优缺点,并考虑施工成本和安全性的基础上,本文提出了一种新型的耙缆式地震勘探技术.该技术通过一条长缆和多条短缆的组合来实现超小面元的地震勘探.通过使用高频(主频100~150 Hz)震源来实现高分辨率地震勘探.实际数据的模拟处理显示了耙缆式地震勘探的有效性.在对比耙缆式技术与其他技术的优缺点的基础上,针对耙缆式勘探与传统三维地震勘探的不同指出了需要发展的一些处理和解释技术.最后,还指出该勘探方式可以推广到海底高分辨率调查的其他领域.基于目前的三维地震勘探条件进行适应性改造能够很好地开展耙缆式地震勘探.

As the gas-hydrate production test succeeded, the plan of commercial production is also on the agenda. Gas hydrate production requires more accurate characterizations and evaluation of the gas hydrate accumulations, which demands seismic data of higher resolution. The gas hydrate reservoir is characterized by shallow burial, non-uniformity and thin thickness. Current seismic techniques can not provide fine characterization of the gas hydrate reservoir since high-resolution and small-size bin seismic data is not available. Considering the advantages and disadvantages of the existing seismic techniques, and considering the cost and safety issues, this work propose a new type of seismic exploration technique with the geometry in the shape of a harrow. High resolution seismic data is achieved by using a high frequency source with a dominate frequency of 100~150 Hz. Small-size bin is achieved by a combination of close-spaced short cables and a long cable. Partial data simulating the harrow-like geometry are extracted and then processed following the conventional flow. The result shows the effectiveness of new technique. The harrow-like technology is compared with other technologies and some differences are pointed out from the processing and interpretation perspectives. It is also pointed out that the newly proposed way can be extended to other fields related to high-resolution survey of the shallow seafloor sediments. The harrow-like seismic exploration can be conducted based on the present 3 D seismic exploration equipment after some modifications.