Plugging Oil Hole
How the device will work
The containment dome, being lowered into the Gulf on Friday, May 6, 2010, is as tall as a four-story building and meant to cap the oil discharge.
BP is taking extreme caution as they lower a containment dome about as tall as a four-story building to the bottom of the Gulf of Mexico today in an effort to stem the flow of oil still gushing from a damaged pipe after the Deepwater Horizon rig exploded and sank on April 22. This is the first time an oil recovery system like this has been used in such deep waters. Though there are risks and uncertainties, if successful, the dome could collect 85 percent of the leaking oil, which is currently gushing out at a rate of 5,000 barrels a day. "This has never been done in these sorts of depths at all before," BP spokesperson Jon Pack told LiveScience. "This is 5,000 feet. We're taking a lot of time to do it properly and to do it as safely as we can. The dome is currently on its way down, and it's about 500 feet [152 meters] from the seabed." At least a few more hours will be needed before the dome hits the seafloor, Pack said in a telephone interview early Friday afternoon. Because you're aiming for a terribly tiny target, you really have to take that very slowly indeed," he said. "The operation of putting the dome in place has been likened to heart surgery." The device weighs about 125 tons and measures 14 feet by 24 feet by 40 feet (4 meters by 7 meters by 12 meters). As for why it's dome-shaped, Pack said curves are always stronger than straight edges, meaning a curved container will do better at keeping all that oil trapped. [Graphic: Putting the Dome in Place] Once lowered, remotely operated vehicles (ROVs) will carefully position the dome over the end of a pipe (also called the riser) where the source of the largest leak is occurring and which is about 600 feet (183 meters) from the well head. There are several slots on the sides of the dome with sliding doors so the dome can be clamped around the broken riser. The dome will actually go into the seabed. The ROVs are equipped with powerful lights and cameras, as well as the robotic arms they'll use to do the positioning. Images of the process will be transmitted to computers onboard the ship, so officials can monitor what's going on. The goal is to create a seal between the seabed and the dome, which can be tricky. Then, a 5,000-foot (1,524 meters) riser will be connected to the top of the containment dome, and that riser will go up to the Deepwater Enterprise. Once sealed to the seabed, it will take a couple of days to get everything hooked up, Pack said. Then, it will take time to "get the balance of liquids right." That's because as the oil flows out of the ground and travels higher up the pipe, gases that are beginning to come out of solution can form hydrates. These hydrates are like ice crystals and can reduce the internal diameter of the pipe and so block it (like plaques blocking an artery). In order to prevent the formation of hydrates, warm seawater is being pumped down in the space between the drill pipe (where the oil is flowing to the ship) and the outer pipe. When the collection process gets going, oil will fill up the dome and then under its own pressure, it will flow up the riser and be collected on the ship, where it will the oil will be separated from the water and gas and temporarily stored before being transferred back to shore. ..................................................................................................
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