Relief Well Getting Close

According to the latest reports, BP's relief well drill is getting very close to the pipe of the leaking well. However, it is still uncertain how long it will take to bore through the pipe and plug it.

The first of two relief wells is within striking distance of the Macondo, about 15ft (4.5m) away from the pipe and 600ft or so (200m) above the reservoir, after weeks of drilling. The second, ordered by the Obama administration as a safety back-up, is some weeks behind....

The most important thing is establishing a clear connection with the Macondo so they can begin pumping in the heavy drilling mud according to Mark Proegler, a BP spokesman. A nick risks starting a new small leak or possibly even a collapse of a section of the pipe given that it was damaged in the explosion in ways still not fully understood.

Those challenges are still some days away as BP continues to find the optimal point to break into the well, a process known as ranging. "We have many days ahead of us of ranging runs," said Proegler. The process involves lowering a device down the relief well that bounces electromagnetic waves through the rock to try to measure the distance to the metal pipe of the Macondo, a target barely seven inches (18mm) in diameter.

There are still a few things that could go wrong when the drill bit meets the pipe.

The intercept could be complicated if it turns out that the oil is flowing around the pipe, between the pipe and the cement of the well bore.

Engineers also have to be spot-on in their calculations as to how much drilling mud – or pressure – to exert on the well to choke it off. A vessel containing 44,000 gallons of mud is on standby.

The mud must be viscous enough to flow down the pipe but also dense enough to slow down the oil bubbling up from below.

From what I have read, BP has basically one chance to stop the flow once they puncture the well pipe. This procedure should work, and it has worked for other wells, but the spill could get worse if it is not done correctly.