The facts are not in dispute, but the cause is. The well was drilled to T.D. and secured. The rig was within a few hours of moving to its next location. A bottom hole cement plug was set and tested. About the only thing left to do was set the top plug, displace the riser, disconnect and move.
For some yet-to-be-explained reason, the owners of the well decided to displace the riser (and 3,000 ft. of hole) with seawater before setting the top plug. As they were displacing the mud, they were pumping the mud overboard to a work boat to be used again. Displacement is a complex process where mud in vs. mud out is carefully monitored, but since they were pumping off, no one noticed that they were getting more mud back than they were displacing with seawater. This is because gas was coming into the hole – from where may take years to determine, longer if we let Congress do it. By the time the crew realized they were taking a kick, the gas was above the blow-out preventers. On this well, the blow-out preventers (BOPs) were at 5,000 feet below the rig. Consider this: One cubic foot of gas at 5,000 feet = 700 cubic feet of gas at the surface. By the time it approached the surface, nothing could stop it.
It was a calm day, so the gas didn’t blow away, it just accumulated under the rig. Then the rig engines started inhaling the gas and ran away. Witnesses say, “The lights and computer screens got brighter just before the explosion.” Since the pumps were on, they ran away too, speeding up until they cavitated and inhaled the gas. Then the pumps “dieseled,” initiating the explosion. It blew the pumps through the pump room wall into the Gulf. All telemetry stopped. We know what happened next.
Probable CausesVery seldom is an accident caused by just one thing, but one thing can trigger it. Think of the old saying, “For want of a nail, a shoe was lost, for want of shoe, a horse was lost, for want of a horse, a rider was lost,” etc. There probably were several contributing factors to the blowout.
This incident probably will fuel conspiracy theories for years. The ‘tin-foil-hat’ brigade – my mother included – even has said that the North Koreans sabotaged the rig with a miniature submarine. More likely contributing factors include that the well originally was designed as an exploration well, not a production well. When BP realized how good the well was, the company decided to put it online. Only it was too late to change certain engineering requirements, like how much cement to pump at each casing shoe. Did this contribute?
Next, setting the top plug in seawater instead of mud. Seawater displacement lowered the hydrostatic head on the well too much. Did this contribute? Next, it is known that the BOPs were modified to allow the required testing to be done faster. Did this contribute? Did the crew properly monitor the seawater-in to mud-out ratio pro-perly? Was the WOC (waiting-on-cement) time adequate at this depth and temperature? It is obvious that BP wanted to move the rig as soon as possible; after all, it cost $500,000 a day. Bet they’re not too worried about a paltry million right about now ….
There probably was not a single cause to this disaster, and there won’t be a single solution. To put it into perspective, consider this: Oil has seeped into the surface environment for millions of years. People used it for medicines and many other purposes. The first commercial producing well in the United States – the Drake well in Pennsylvania – was drilled because it was near a seep. All of this oil entering our environment has caused no long-term damage because there are naturally occurring bacteria that eat it. The process works remarkably well.
The environmental lobby still likes to cite the Exxon Valdez spill in Alaska as a reason why we should never drill anywhere. What they don’t bother to mention: In the area that had all the rocks steam-cleaned, at a cost of millions, they managed to assuage their guilt and drive the oil deep enough under the rocks so that natural forces couldn’t deal with it. Go there now, and you can turn over rocks with oil under them. Go a few miles up the beach, where no cleanup was done, and you can’t find a trace of oil. Wonderful thing, nature. One good hurricane probably will help a lot, and might even make some people understand that they shouldn’t live below sea level unless they wear wooden shoes.
The news media will continue to demand result without even knowing the terms to describe the problem. One of their favorites seems to be “blow-out protector” rather than blow-out preventer. For those readers who have journalism degrees instead of dirt under their fingernails, I’ll explain: These devices prevent blowouts, not protect them. One of the flunkies said recently that if BP didn’t do better, they’d just “push them out of the way and take over.” And do what? I doubt most of them could drill a cow-pie out of a churn. BP has more deepwater experience than almost anybody, and are doing all they can. Let’s let them do it, and start the dog-and-pony-show later.