Pushed back: Debris in the wellbore sets back kill operations.
Wellbore debris delays static kill
BP has likely pushed back plans to begin kill operations on the Macondo blowout in the US Gulf of Mexico after crews found debris in the well that had to be cleared before they coudl run the final casing string.
BP had planned to try the first phase of the operation to kill the well – the static top kill – on Monday but it likely will be pushed back to Tuesday, retired Coast Guard Admiral Thad Allen told reporters Friday.
Crews on Transocean semi-submersible rig Development Driller 3 were supposed to run 2000 feet of 9-7/8 inch casing and cement it in place beginning Thursday but encountered a set back when they re-entered the well, which had been shut in with a storm packer while Tropical Storm Bonnie passed.
“The last 40 to 46 feet, we found some debris where [the wellbore] just kind of settled in on itself while the storm was passing,” Allen said.
“We had to go down and clean that out and it’s going to take probably about 24 hours to do that, so we may have a one or day-and-a-half delay to actually clean the casing which will delay the top kill by about the same amount of time.”
The debris does not endanger the relief wellbore at all, Allen said.
“At the very end of the well bore basically all it is, is a hole that’s been drilled out in a formation and some of the sediment around the sidewalls just kind of fell in on itself,” he explained.
“If you can imagine if you drilled a hole and did not put a pipe down to reinforce it we had about 40 feet where it just settled in on itself. It’s not a huge problem but it has to be removed before you can put the pipe casing down so that’s what’s being done today.”
When the static top kill begins, the Helix Energy Solutions service platform Q4000, will pump drilling mud through the kill line of the old Macondo blowout preventer to tamp down the flow of the well.
Most likely the mud will be followed by cement but BP will not make that decision until after mud has killed the well and it has been monitored.
The whole process will take about 24 hours.
The Q4000 is already in place, hooked to mud and pumping vessels, but BP wants to make sure the relief well is cased and secure before beginning the job.
For an explanation of the kill efforts go here .
BP remains on schedule to intercept the Macondo blowout in the US Gulf in less than to weeks.
After the top kill , Development Driller 3 can begin drilling the final 100 vertical feet into the annulus of Macondo, which is expected to take about five days because crews will stop every 20 to 25 feet to locate the Macondo wellbore.
When the rig hits the annulus it will begin pumping mud for the bottom kill operation,
Once any flow in the annulus has been stopped, the mud will be followed with cement.
Finally, the semisub will drill into the main bore to ensure that the kill and cement job from the static kill was effective.
“I think it's going to be a question of once we hit it we'll know,” he said.
Allen said he hoped that the static top kill would take care of all the flow but regardless the semisub would drill into both areas to make sure.
“We can do the top kill or the hydrostatic kill and actually potentially bring the pressure of the stacking cap to zero,” he said Friday.
“We're not going to be satisfied until we actually drill into that annulus outside the pipe and actually fill that with mud which I think we need to do and if we need to we'll actually drill back into the pipe just to make sure from the bottom up that we've totally killed the well.”
For a diagram of the relief well go here.
Pressure on the capping stack that has kept Macondo shut for two weeks is at about 6969 pounds per square inch and rising at less than 1 psi per hour.
Monitoring has not revealed any concerns about the integrity of the well, Allen said.
"Frankly over the last 14 days, through the seismic surveys that have been done and the acoustic testing we have ruled out any anomalies that would indicate to us that we have well integrity problem," he said Friday.
