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摘要:
浅表层天然气水合物资源勘查是天然气水合物资源勘查的重要组成部分，对深水地质灾害预测和评价、气候变化等都具有重要的指导意义。地震勘探是天然气水合物勘探的重要手段，但浅表层天然气水合物赋存于近海底沉积物中，埋深一般小于海底以下60 m，对地震浅层分辨率具有较高的要求，常规地震勘探方法难以满足以高频信号为主的浅表层天然气水合物勘探的需要。针对浅表层天然气水合物的特点，充分利用小道距高分辨率多道地震电火花震源气泡效应小、可重复性好，激发频率高、接收系统动态范围大等特点，结合参量阵浅地层剖面，形成了一套高分辨率地震勘探方法，提高了浅部地层的地震分辨率，满足了浅表层天然气水合物勘查对资料分辨率的要求。浅表层天然气水合物似海底反射（BSR）不明显，通常与海底甲烷渗漏密切相关，因此海底气体渗漏相关的地形地貌、气体运移通道、速度异常和振幅异常等特征是浅表层天然气水合物的重要识别标志。
Abstract:The shallow gas hydrate is a very important exploration target of gas hydrate resources. It is also very important for prediction and evaluation of deep-water geo-disasters and their climatic consequences. Seismic exploration is a basic mean for gas hydrate exploration. However, the shallow gas hydrate occurs in the sediments near the seafloor, of which the buried depth is generally less than 60 m, and dominated by high frequency signals. Therefore, it requires a high shallow seismic resolution. Conventional seismic exploration methods are not able to meet the needs in the shallow gas hydrate exploration. According to the characteristics of shallow gas hydrates, we proposed in this paper a high-resolution seismic exploration method, which fully uses the advantages of small-scale high-resolution multichannel seismic technology, combined with the parametric array sub-bottom profile. This method has much improved the seismic resolution for the shallow deposits, and good enough to meet the requirements of data resolution for the shallow gas hydrate exploration. The bottom simulating reflector (BSR) of the shallow gas hydrate is usually not so obvious, and closely related to methane leakage. Therefore, the geomorphic features related to gas leakage in the seafloor, gas migration pathways, velocity anomalies and amplitude anomalies are important indicators for recognition of shallow gas hydrates.
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