内波是一种水下波，通常发生在分层介质中，是在海洋内部密度不均匀水层间发生的一种波动。只要海水密度稳定分层，并有扰动源存在，内波就会产生。由于内波的能量比相应的表面波小得多，只需小小的扰动就能引起内波的形成，且这种扰动是普遍存在的。因此，内波像海面波浪一样广泛于各大洋中，只是其波长、振幅、周期、传播速度及存在深度有很大的变化。由于内波的存在，在界面上下水质点运动的方向相反，在界面处发生最大速度剪切，可形成速度可高达1.5 m/s以上的内波流，破坏力极大。目前所知世界上最大的内波流——中国南海内波流的振幅高达 150 m，约 50 层楼高^[1]。中国南海是内波灾害发生最频繁的海域，给深水油气资源的开发带来了巨大的安全隐患。

An internal wave is an underwater wave that usually occurs in a stratified medium and is a fluctuation that occurs between layers of water with uneven density within the ocean. Internal waves are generated whenever seawater density is steadily stratified and a source of perturbation is present. Since the energy of internal waves is much smaller than the corresponding surface waves, only a small perturbation is needed to cause the formation of internal waves and this perturbation is universal. Therefore, internal waves are as widespread as surface waves in all oceans, except that their wavelength, amplitude, period, spread speed, and depth of existence vary greatly. Due to the existence of internal waves, the water masses above and below the interface move in opposite directions, and the maximum velocity shear occurs at the interface, which can form an internal wave flow with a velocity of up to 1.5 m/s or more and a great destructive power. The amplitude of the world’s largest known internal wave flow - the South China Sea internal wave flow - is as high as 150 m which is the height of about 50 stories. The South China Sea is the area where internal wave disasters occur most frequently, which poses a huge safety hazard to the development of deep-water oil and gas resources.

图1海洋内波

 内波虽不像海面波浪那样汹涌澎湃，但它隐匿水中，暗中作祟，常使人们防范不及，故有"水下魔鬼"之称。加拿大戴维斯海峡深水区的一座石油钻探平台，就曾遭内波袭击而不得不中断作业，为此，美国英特俄辛公司为其安装了内波预警系统，以保障其安全作业。内波峰高谷深，垂直作用也很大。1963年4月10日，美国"长尾鲨"号核潜艇，在大西洋距波士顿港口350公里处突然沉没，艇上160人无一生还，事后经过对沉入海底，变成碎片的残骸分析判断，下沉的原因是潜艇在水中航渡时，遇到了强烈的内波，将其拖拽至海底，承受不了超极限的压力而破碎，这就是强大内波垂直力作用的后果。

Although the internal waves are not as billowy as the surface waves, they are hidden in the water and occur when people are unprepared, so they are called “underwater devils”. An oil drilling platform in the deep water of Davis Strait, Canada, was attacked by internal waves and had to interrupt the operation, for which the U.S. Interocean installed an internal wave warning system to ensure its safe operation. On April 10, 1963, the U.S. nuclear submarine “Thresher Shark” suddenly sank in the area of Atlantic Ocean 350 kilometers from the port of Boston, and 160 people died in that accident. After the analysis of the wreckage that sank to the bottom of the sea and turned into debris, the reason for the sinking was that the submarine encountered strong internal waves which dragged it to the seabed, and the submarine could not withstand the extreme pressure and broke up. This is the consequence of the vertical force of the powerful internal waves.

 由于受海洋水文环境监测手段的限制，当前研究成果还无法对海洋内波出现的时间和地点进行准确预测。海洋内波在中国南海北部具有分布区域广，活跃时间长，传播速度较快等特点，在南海北部区域尤其是东沙海域作业时与之相遇无法避免^[2]。因此，对南海内波流的理论研究亟待进一步发展，从而对深水工程实践中的内波流所造成的影响进行更加深入的分析研究。

Due to the limitation of the ocean hydrographic environment monitoring means, the current research results cannot accurately predict the time and place of the appearance of oceanic internal waves. The ocean internal waves in the northern part of the South China Sea have the characteristics of wide distribution area, long active time, and fast spread speed, and it is unavoidable to meet with them while operating in the northern part of the South China Sea, especially in the East China Sea. Therefore, the theoretical research on the internal wave flow in the South China Sea needs to be further developed so that the impact caused by the internal wave flow in deep-water engineering practice can be analyzed and studied more deeply.

参考文献

[1]胡伟杰,刘正礼,陈彬.南海内波流对深水钻井的影响及对策[J].石油钻采工艺,2015,37(01).

[2] 宋玲安.海洋内波流对深水钻井影响技术分析.石化技术, 2021, 28(07): 67-68+62.