BP Moves On To Tricky New Fix To Capture Oil

An image from the BP oil spill i i

This image made from video released by BP shows the gushing oil well in the Gulf of Mexico on Sunday. Six weeks after the catastrophe began, oil giant BP is still casting about for at least a temporary fix to the spewing well underneath the Gulf of Mexico that's fouling beaches, wildlife and marshland. AP/BP PLC hide caption

itoggle caption AP/BP PLC
An image from the BP oil spill

This image made from video released by BP shows the gushing oil well in the Gulf of Mexico on Sunday. Six weeks after the catastrophe began, oil giant BP is still casting about for at least a temporary fix to the spewing well underneath the Gulf of Mexico that's fouling beaches, wildlife and marshland.

AP/BP PLC

As the Deepwater well continues to gush, BP is preparing another stopper to stanch the flow of oil and gas into the Gulf of Mexico while it drills relief wells to permanently kill the well.

The oil and gas are flowing from a bent pipe — a "riser" — that comes up from the well and through a large, valve-like device called a blowout preventer.

The new fix is called a lower marine riser package (LMRP) and is essentially a metal cap. Engineers will lower the cap over the blowout preventer. The preventer was supposed to clamp off the well bore when the original blowout occurred last month, but failed. The cap is like a bottle cap that meets with the preventer and squeezes it closed to keep as much seawater out as possible. If all goes well, the oil and gas will flow up into the cap and through a pipe to be collected by a ship on the surface.

BP officials won't predict the chances of success; all previous attempts to stop the flow have failed despite initial BP statements of optimism. They say they'll need about four days to set up the procedure.

A Tricky Procedure

The LMRP procedure won't be easy. First, a robotic submarine has to cut off the bent riser pipe that's sticking out of the preventer. BP executive Doug Suttles says there is a chance that cutting off the riser actually could increase the flow of oil and gas up the riser, since it will eliminate the kink that may be constricting the flow now. Suttles says engineers believe chances of success outweigh that risk.

There is also the problem of icelike crystals of methane hydrate. A previous attempt to capture and divert the oil with a much larger containment dome failed because too much seawater was trapped and mixed with gas to form those crystals. The crystals then blocked the pipe that rose from the containment dome.

BP engineers are considering one other option: placing another blowout preventer on top of the original one that would clamp off the riser the way the first one was supposed to.

Two Relief Wells Being Drilled

As all this takes place, BP is drilling two relief wells miles away from the Deepwater well that are intended to intersect it and fill it with drilling mud and cement. The target well bore is less than a foot in diameter, and the relief wells will have to go through miles of rock to find it. Engineers have the benefit of 3D seismic imaging, however — a technique that gives them a precise three-dimensional map of what's under the seafloor. And instruments near the drill bit measure exactly how far and in which direction the bit is moving during drilling. It's a bit like plotting a boat's position by knowing where the starting dock was on a chart, and calculating every few minutes how long and how fast you've sailed.

According to Iraj Ershaghi, director of the petroleum engineering program at the University of Southern California, finding the noodle — the Deepwater well bore — is a matter of magnetism. Instruments at the end of the relief well create a magnetic field. Rock doesn't normally show up; the steel well bore does. That way, the drillers can home in on it.

Once the relief well reaches the original well bore, engineers will drill a hole in it and start pumping down drilling mud and cement through the relief and into the Deepwater well until they plug it up permanently. Ershaghi says this too is tricky; if they drill into it from a 45-degree angle, they may not be able to push the cement down hard enough to overcome the force of the rising oil and gas. He says the relief well probably should connect at an angle no greater than about 20 degrees from directly overhead.

BP officials say it could take until August to drill the relief wells.

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