Natural gas hydrate (NGH) is a potential clean alternative energy source for fossil fuels. In seismic imaging profiles, NGH is often identified by the bottom-simulating reflection (BSR), which is characterized by strong reflection amplitude and negative polarity. High-resolution and amplitude-preserved seismic imaging are demanded for the detection of NGH. However, the traditional acoustic reverse-time migration ignores the attenuation characteristics of the medium, which leads to reduced amplitude and distorted phase of the seismic wave. In particular, when the hydrate saturation is low or the underlying formation does not contain free gas, it is difficult to observe the identifiable BSR in the traditional acoustic imaging profile, which causes difficulties in the identification of NGH. Here, we introduce the fractional viscoacoustic wave equation to perform the Q-compensated reverse-time migration (Q-RTM) for NGH, which can accurately recover the amplitude loss, correct the phase distortion, and provide high-resolution and high-illumination imaging results. Finally, Q-RTM can effectively enhance the BSR, reduce the uncertainty of hydrate identification, help to confirm the location and spatial distribution of the gas hydrate-bearing sediments, further refine the geological properties, and provide some theoretical basis for the exploitation and drilling of hydrate.

中文翻译：

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基于分数粘声波方程的天然气水合物 Q 补偿逆时偏移

天然气水合物（NGH）是一种潜在的化石燃料清洁替代能源。在地震成像剖面中，水合物通常通过模拟底部反射（BSR）来识别，其特点是反射幅度强、极性为负极性。水合物探测需要高分辨率和保幅地震成像。然而传统的声波逆时偏移忽略了介质的衰减特性，导致地震波振幅减小、相位畸变。特别是当水合物饱和度较低或下伏地层不含有游离气时，传统的声波成像剖面很难观测到可识别的BSR，给水合物识别带来困难。在这里，我们引入分数粘声波方程对NGH进行Q补偿逆时偏移（Q-RTM），可以准确恢复幅度损失，校正相位失真，并提供高分辨率和高照度成像结果。最后，Q-RTM可以有效增强BSR，降低水合物识别的不确定性，有助于确定含天然气水合物沉积物的位置和空间分布，进一步细化地质性质，为开采和钻探提供一定的理论依据水合物。