The Hurricane Powered Delta Mudflow Transportation System
29 September 2010 Houston Branch OSIG Learning Luncheon, Houston, Texas, USA
Report
On 29 September 2010, the SUT held a learning luncheon at Norris Conference Center in Houston, Texas. The afternoon event was well attended with sixty-eight attendees. The speaker was Jim Hooper, a Geotechnical Engineering Consultant specialising in Marine Biohazards.
In the presentation, Jim discussed how waves from Hurricanes Ivan (2004) and Katrina (2005) generated thousands of large-stress, positive and negative pressure cycles against the seafloor during the time they shoaled into the Mississippi Delta. Huge mudflows were triggered across the shallow water and mid-slope regions of the delta. They flowed far down the delta front, thoroughly disrupting the oil and gas pipeline transmission network within their paths.
While mudflows are not unexpected on the submarine delta seafloor, the size of the individual flows, and the water depths that they penetrated during the Ivan and Katrina events, were greater than any that had been experienced within the last several decades of exploration and development in the Mississippi Delta. It is notable, however, that some of these new mudflows seem to be resting on, but are not fully covering, the downslope extensions of older, larger events. Apparently, the Ivan and Katrina mudflows are not the worst seafloor failures that have occurred in the Mississippi Delta.
This discussion reviewed the fundamental characteristics of hurricane wave-delta seafloor interaction, addressing questions such as:
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Why do large mudslides occur in the Mississippi Delta, and not elsewhere in the Gulf of Mexico?
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How do large ocean waves transform weak, but otherwise perfectly stable, seafloor sediments into, for instance, 40ft-thick, near-liquid layers that can travel miles downslope on near-zero degree gradients?
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How can the delta seafloor control hurricane waves such that the dynamic energy components of the largest waves are filtered from the storm's energy spectrum, and only the smallest waves remain?
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What methods do engineers use to counter or avoid the effects of mudslides when they design production platforms, pipelines, and other seafloor supported facilities?
The luncheon had great reviews and the branch looks forward to the next OSIG learning luncheon. The next luncheon is scheduled for Wednesday, 1 December 2010. The topic for this event will be determined soon.
To view the presentation, visit www.SutHouston.com under ‘Special Interests’.