The current controversy over expanding offshore oil exploration and production includes an important consideration: during Katrina and the other hurricanes that hit the Gulf coast during the middle of the decade, there were no oil spills.
One important reason for this was that none of the platform foundations failed. (Right: one of those pile foundations being installed.)
Driven steel pipe piles are the foundations for approximately 4,000 steel jacket platforms that rest on the sea floor of the Gulf of Mexico. More than 100 platforms were destroyed in these three hurricanes combined, which essentially tripled the number of platforms destroyed by hurricanes in the history of oil and gas production in the Gulf of Mexico…
While the damage to offshore platforms from these recent hurricanes was unprecedented, there were few if any failures of pile foundations either axially or laterally…The photograph (not included) shows the leg of a steel jacket near the mudline. The outer jacket that the pile was inserted through failed, while the pile remained intact. The "flange" in the jacket leg was formed by the rocking motion of the platform after the leg ruptured.
The pile foundations performed better than expected. Structural modelling for individual platforms with loads based on hurricane hindcasts indicates that numerous platforms should have failed in the foundation. These results include platforms that actually failed in the jacket above the foundation as well as platforms that did not fail. While there is some conservatism built into the pile foundations for offshore structures, there is now a wealth of information to better understand the actual capacity of full-scale pile foundations under design loading. Offshore piles are about an order-of-magnitude larger than those in the pile load tests originally used to develop the methods for predicting capacity.
A more realistic assessment of foundation capacity will be an important contribution from these recent hurricanes, particularly since design loads are increasing and foundation capacity is likely to limit the design of new platforms and the re-qualification of existing platforms. Ongoing research aims to improve these predictions. (Gilbert, R.B., "Offshore Experiences in Recent Hurricanes." GeoStrata, January/February 2007, pp. 28-31)
Foundation integrity is essential to the shut-off technology at the sea floor to work properly and prevent leaks. This is a tribute to those who designed and built these structures.
Like anything else in this world, a firm foundation is essential:
In fulfillment of the charge which God had entrusted to me, I laid the foundation like a skillful master-builder; but another man is now building upon it. Let every one take care how he builds; For no man can lay any other foundation than the one already laid-Jesus Christ. (1 Corinthians 3:10-11)