Short- and long-term movement of mudflows of the Mississippi River Delta Front and their known and potential impacts on oil and gas infrastructure
Short- and long-term movement of mudflows of the Mississippi River Delta Front and their known and potential impacts on oil and gas infrastructure
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DOI：
10.1144/sp500-2019-183
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发表时间：
2020-03
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影响因子：
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通讯作者：
J. Chaytor;W. Baldwin;S. Bentley;M. Damour;Douglas Jones;J. Maloney;M. Miner;J. Obelcz;Kehui Xu
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文献类型：
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作者：
J. Chaytor;W. Baldwin;S. Bentley;M. Damour;Douglas Jones;J. Maloney;M. Miner;J. Obelcz;Kehui Xu
摘要密西西比河三角洲前缘（MRDF）的泥流是公认的对墨西哥湾浅水区（水深20-300 m）石油和天然气基础设施的危害。高沉积速率加上斜坡过陡、固结不足和大量生物气生产，导致海底发生破坏的预处理。在1969年的卡米尔和2004年的伊万等罕见的大飓风期间，由于海底位移，生产平台和管道发生灾难性故障，这表明波浪对海底的周期性加载是主要的运动触发因素。由于数据的限制，较小的风暴和背景海洋学过程在驱动海底移动方面的作用基本上仍然不受限制，但这些被认为有助于显著的海底变化。借助新的高分辨率多波束测绘和MRDF各部分的地震反射剖面，对变形三角洲前缘环境中的几个移动特征进行了调查，并讨论了对该区域附近安装的基础设施的潜在危害。通过对选定区域的重复测绘调查和沉船位置变化的记录，我们强调了每年到十年时间尺度的重大海底位移。例如，在西南山口附近的泥流冲沟内绘制的个别区块显示，一年内的下坡运输量超过80米，而1942年沉没的153米长的油轮SS Virginia已经重新定位，发现在14年内下坡移动超过400米，没有一个大飓风（> 2级）经过该地区。
Abstract Mudflows on the Mississippi River Delta Front (MRDF) are recognized hazards to oil and gas infrastructure in the shallow (20–300 m water depth) Gulf of Mexico. Preconditioning of the seafloor for failure results from high sedimentation rates coupled with slope over-steepening, under-consolidation and abundant biogenic gas production. Catastrophic failure of production platforms and pipelines due to seafloor displacement during infrequent large hurricanes such as Camille in 1969 and Ivan in 2004, point to cyclical loading of the seafloor by waves as a primary movement trigger. Due to data limitations, the role of smaller storms and background oceanographic processes in driving seafloor movement has remained largely unconstrained but these are thought to contribute to significant seafloor change. With the aid of new high-resolution multibeam mapping and seismic reflection profiling across sections of the MRDF, several moving features within the deforming delta-front environment are investigated and potential hazards to infrastructure installed and adjacent to the region are discussed. Via repeat mapping surveys of selected areas and records of changing shipwreck locations, we highlight significant seafloor displacement across annual to decadal timescales. For example, individual blocks mapped within mudflow gullies adjacent to Southwest Pass show downslope transport of more than 80 m in a single year, while the SS Virginia, a 153 m-long oil tanker sunk in 1942, has been relocated and found to have moved downslope more than 400 m in 14 years, without a major hurricane (>Category 2) passing through the region.