New Cap Could Seal Well as Relief Drilling Continues

Efforts to place a new containment cap over the Gulf of Mexico oil well could nearly halt the spill as early as Monday, according to U.S. officials. Meanwhile, advanced technology has been guiding the drilling of two relief wells in an effort that has been BP's long-term back up plan to halt the gushing oil.

Admiral Thad Allen, who oversees the government's spill response, told AFP that an operation to swap in the new cap could begin Saturday and the entire process would take "about three to four days."

Current government estimates of the spill range from between 35,000 to 60,000 barrels a day, based on interpretation of a live video feed of the leak. The new cap could capture nearly all of the crude spilling into the Gulf and allow it to siphon up to container vessels on the surface, Allen told AFP.

If the cap doesn't work, engineers are hopeful relief wells will do the trick.

For over two months, engineers have been drilling through thousands of feet of water, mud, and rock using a sophisticated suite of high tech sensors. The first relief well is now hundreds feet from the blown well, while the second well is still a good distance away, according to BP.

The first relief well will stop when it hits a hollow, seven-inch target more than three miles beneath the surface of the Gulf of Mexico. That might sound like a difficult target to hit, but it's key. The idea is to drill the relief wells so they intersect the original well below the seabed on a diagonal. Then engineers can flood the relief wells with mud and concrete to stop the uncontrolled flow.

And Jerome Schubert, a petroleum engineer at Texas A & M University, points out relief wells have been used for decades to stop problematic wells.

"I've got a telegram from Western Union to Kodak about a relief well being drilled in Texas in 1933," said Schubert.

The pipes might be longer, and the pressures greater, but the technology to find a gushing oil well has also improved dramatically. Decades ago, drillers would lower a compass and camera into a well and take a picture of the needle. After the film was developed, the drillers adjusted the drill accordingly to keep it on track.

Today drillers still rely on magnetic fields to determine a pipe location, along with a suite of other sophisticated sensors. Magnetometers and accelerometers will determine the relief well's position, angle, and direction. The magnetometers will also determine how close the relief well is to the steel pipes of the blown well.

These tools give information about the drill. But drillers also need to know about the environment they are drilling through. Other sensors, embedded in the wall outside the drill and shaped like torpedoes, determine whether the drill is in rock, sand, or oil, how viscous that oil is, and other information that is relayed back to the drill operators.

All this information is critical to ensure the drill goes where its needed. Without reliable information, the drill could hit rocks of different hardness or bend under the pressure and veer off course. If the relief well is off target for any reason special pressurized pads on the drill head can be inflated to steer the drill in the necessary direction.

These sensors have gotten the drill to its current location, less than 20 horizontal feet and less than 1,000 vertical feet from the blown well. As the relief wells get closer and closer to the blown well it should get easier and easier, said Andrew Wojtanowicz, a professor at Louisiana State University and editor of the Journal of Energy Resources Technology.

Hitting the blown well with the relief well will be like steering a boat towards a weir in a river, said Wojtanowicz. Point it in the right direction, and let the current do the rest. The flow of oil and the formation of the rock will naturally pull the relief well towards the blown well.

According to a recent statement from BP, the two wells could intersect as early as July 20th. That's one week before analysts expect BP will report its second-quarter earnings to investors. That date could be delayed however, if technical problems or storms in the Gulf of Mexico force them to suspend drilling operations. In any case, BP revised date is sooner than its early estimate of an August interception.

Once the relief well intercepts the the blown well, heavy drilling mud will be pumped into the blown well. equalizing the pressure between the salt water above and the oil below. Then cement will permanently seal the blown out well.

One way or another BP will eventually seal the well, said Wojtanowicz, but, he added, the task of cleaning up will continue.

"What happens next, once they've killed the well, that is a completely different task," he said.