Hydrates slowed removal of pipe from Macondo well, Oil and Gas Journal, Aug 25, 2010:
[National Incident Commander Thad Allen] said the third pipe, previously estimated at 3,000-3,500 ft, might... [require BP] to remove the pipe while it’s still attached to the BOP, Allen said, adding that BP is formulating plans to do that if necessary.
There also is a chance that the pipe might be in contact with cement that was pumped into the well during the earlier “static kill” process.
“We’re not ruling out the possibility that some cement could have adhered to it,” Allen said. Consequently, BP engineers and federal scientists are studying “how much pull should we put on the blowout preventer.”