BP published its internal investigation report for Deepwater Horizon rig explosion at Macondo well in the Gulf of Mexico on April 20, 2010 (Links to Video, Presentation Slides, Executive Report and Full Report are below).
The investigation found eight major factors that contributed to Macondo well explosion and oil and gas leak. A sequence of failures involving a number of different parties, mainly BP, Transocean and Halliburton, led to the explosion and fire which killed 11 people and caused widespread pollution in the Gulf of Mexico.
BP’s managers and contractors involved with well exploration made mistakes that contributed to the tragedy. In its report BP blamed many of the errors on Transocean Ltd, the owner of Deepwater Horizon rig, and on service provider Halliburton Co.
Bloomberg.Com reports that: “BP’s report concealed the well’s “fatally flawed” design, which “set the stage” for the explosion, Vernier, Switzerland- based Transocean said Sept. 8. The driller, Transocean, cited a series of cost-savings decisions by BP that added risk. Cathy Mann, a spokeswoman for Houston-based Halliburton, said the report had “substantial omissions and inaccuracies” and that BP dictated design and testing procedures for the well.”
As of Tue, Aug 17, 2010 BP is on standby to get government approval to drill final 50 feet to intersect MC252 well annulus (space between rock formation and well casing) at about 800 feet above oil reservoir.
Below are quotes from BP’s briefing with Kent Wells on sealing Macondo well (Aug 10, 2010):
“We do know that we pumped about 200 barrels of cement or so out of the casing. Did it go into the reservoir? Did some go into the reservoir? Did some go up in the annulus? That’s an unknown.”
“We’re planning to intersect the well about 800 feet above the reservoir. And where we are right now with the relief well, we’re just at the shoe of the outer casing. And so we’re now going to start to go down to the place where we can intersect the annulus. And the annulus we’re describing is the annulus between the casing of the Macondo well and just the rock formation. It’s not an annulus between casing and casing. We’re going to intersect it at a point where it’s basically rock and then there’s an annulus and then there’s casing. And that’s where we plan to intersect.”
“And what we don’t know is exactly what we’ll find in that annulus. It could be mud. It could be oil. It could be cement. We just don’t know.”
Kent Wells of BP said on August 6 during the briefing that BP pumped just a little over 500 barrels of cement down the casing. He added “I think it was roughly about 200 barrels into the formation and the rest remained in the casing”. BP plans to remove failed Blowout Preventer after well is killed on August 15 – 20, and install a formal plug during regulatory abandonment procedure.
Starting from mid June, Congress made multiple requests to BP to explain condition of the leaking well and provide facts about possible oil leak into rock formation surrounding the wellbore (read letters here).
All along since the Macondo Well ruptured on April 20 in the Gulf of Mexico, BP was designing a well cap from “scratch” with two objectives in mind: 1) to contain all leaking oil and 2) to have possibility to shut-in the well. As we learned from Congress, Steven Chu, Admiral Thad Allen and independent sources BP knew about sea floor oil leaks they discovered during Top Kill operation, but was not forthcoming about oil sipping from sea floor.
It is not surprising after Top Kill procedure BP’s press briefings did not mentioned anything about designing an impermeable well cap. The first week of July BP installed mini Blowout Preventer, a cap with three RAM valves that serves dual purpose: to contain all leaking oil and to shut-in well if wellbore can hold oil reservoir pressure.
Admiral Thad Allen said it took so long to design this cap because BP had to manufacture and test this specially designed cap from scratch.
Kent Wells of BP mentioned in one of BP’s briefings that Macondo well will be considered intact, or unbroken, if wellbore can hold 8,000 – 9,000 psi pressure during well integrity test. If pressure is found significantly lower than 8,000 psi that would imply oil sips into surrounding rock formation. Oil leaking into rock formation poses a great risk of sea bed erosion and all measures are taken to avoid such outcome.
BP has installed and bolted down an adapter, called ‘spool’, on top of failed Blowout Preventer (BOP) at leaking well (Macondo, MC252) in the Gulf of Mexico. An installation of a stack of valves on top of spool is currently in progress. Pictures of a spool adapter and of a stack of valves are shown below. Once stack is installed, BP will commence well integrity test to determine if well can hold pressure (shut-in pressure) without deterioration of rock formation or seabed leaks.
Should the well pass the 48-hour pressure test, BP may shut it, Doug Suttles, the company’s chief operating officer for exploration and production, told reporters today on a conference call. The test will start as early as this morning, once a stack of valves is bolted atop spool adapter, he said. A relief well BP is drilling will still be needed for a permanent plug.
BP’s Macondo well has been leaking into the Gulf of Mexico as much as 60,000 barrels of oil a day, according to a government estimate, since an April 20 drilling-rig explosion that killed 11 workers. The pressure test, to be monitored by seismic sensors on the seafloor, may determine whether the well bore can withstand the pressure of being shut, National Incident Commander Thad Allen said today in a CNN interview.
Picture:Sealing Cap, an assembly of Spool Adapter and Stack of Valves.
Picture: Spool Adapter (top) and an imitation of Blowout Preventer opening (bottom)
Viking Poseidon ROV recorded on June 13th, 2010 at 2:58 AM EST oil leaking from seabed near MC252 well in the Gulf of Mexico. ROV was located about 55 feet away from the leaking well head when it came across oil seeping from the ground.
BP’s Bob Dudley took questions from PBS and from public on Oil Spill in the Gulf of Mexico. The meeting was aired on PBS and posted on YouTube.
Dudley says he saw reports about fractured sea bed and uncontrolled oil flows at sea floor, including the Russian report circulated recently, but BP’s ROVs do not support this information.
Below is quote from the video transcript (video below) regarding fractured sea floor:
Time Stamp 49min:21sec — >> DUDLEY: I’ve seen some of those reports. We’ve actually taken the ROVs and looked around to see if that’s right. That persists. There’s — I’ve saw a Russian report that said that the seabed was permanently fractured and that there were submarines down there that knew that. I mean, there’s some pretty unusual reports out there. But there’s no evidence at all about fractured seabed and uncontrollable oil.