From David E Brown at 'The Oildrum' a good summary of the present situation - with a minor weight/volume mix up at one point ;-)

"There's a hold on the Relief Well for the moment, although it seems likely that they have instrumentation down there to monitor as best they can from that location what's going on in the blown out well, since that well is about 3.5" from the blown out well, and, if I remember correctly, about 800 ft. above the reservoir.

They have placed a cement plug in the bottom 5,000 ft of the blown out well, probably including the well bore annulus in the part of the well below the reservoir, thus sealing off the production casing from the reservoir.

It is possible that the placed cement also sealed off the reservoir itself and the well bore annulus above the reservoir, but I doubt that they have any way of being sure of that.

Their pressure tests have suggested to them that there is no current unsealed communication between the reservoir and the well-head, although they apparently can't be sure of the status of the annulus outside the production casing, or the annulus between the well bore and the main well casing, beyond determining that there is no active flow through those spaces. They are also not sure whether there is mud, or oil, in either annulus.

They can't be sure that that the original cement seals that were placed outside the casing at the joint of each change in casing diameter as the well was being drilled are still intact.

They cannot be certain about the condition of any of the casing hangers, or their respective seals.

The wellhead has no lockdown sleeve, that device having been apparently deliberately omitted, before the blowout.

The condition of the seals at the wellhead is uncertain, and there is some concern that if excessive pressure is applied inside the well, those seals might become compromised by a lifting of some components of the well casing relative to other parts of the casing.

The original, failed, blowout protector is still in place, with another ram assembly mounted atop it (used to finally cap the well by closing one of its rams), and a riser connecting that to the drill rig.

Mud fills the well above the cement seal at the bottom of the well, sufficient to hold the pressure differential at the mud line (sea bottom) at approximately zero, relative to the pressure in the water at the mud line outside the well assembly.

They have flushed out the mud above the original blowout protector, and probably some of the mud inside that assembly as well, and replaced it with seawater.

There remains inside the well, apparently hanging from the partially closed shear ram and, presumably, any rams below the shear ram, a drill pipe, which is about 3500 ft long, the bottom end of which is some 10,00 ft or so above the cement seal that was just placed at the bottom of the well.

Before replacing and preserving for evidence the original blow-out protector, they would like to extract that drill pipe, to make the removal of the blowout protector less complicated.

In order to "fish" that drill pipe out they need to reach down inside the well with drill pipe with a fishing tool attached at the bottom end until the tool can be attached to the old drill pipe's upper end, having opened the shear ram (if possible) to provide additional access to the old drill pipe for the fishing tool if necessary, but leaving the ram(s)s below the shear ram closed to hold the pipe in place,

The old drill pipe is damaged at the upper end, by being flattened and perhaps partially sheared by the shear ram (probably at a joint between two sections). I don't know whether they have a tool that can be attached to such a damaged end, although it wouldn't surprise me if one were already available for just such circumstances. In any case, even if they don't have a tool for that, they can either cut off that end, or mill that end of the pipe down until they reach the undamaged part of the pipe, attach the extraction tool securely to the lower drill pipe, open the remaining rams on the blowout protector and extract the old drill string, by drawing it up to the drill rig.

While drawing our the old drill string, which is hollow, and therefore will be less likely to create any significant suction effect, at the speeds at which they will extract it, they can replace its weight with mud via the choke and/or kill lines which are attached below the rams.

THen they can remove the new top ram assembly, remove the old blowout protector (although there apparently is some concern about the condition of the latches which attach that to the well head), install a lockdown sleeve if they wish, install a new (thoroughly tested, one would hope) blowout protector, then proceed with the relief well, if they wish to confirm the contents and other conditions within the annulus, and perhaps set a cement seal in the 800 ft or so between the intersection point and the reservoir, while the new blowout preventer reduces the chances of any mishap, especially from any overpressure situations.

With the new blowout preventer they also have the option of perforating the production liner (and casing?) from inside the well to both determine the condition of the annulus, and place any cement that they wish to insert in various parts of the annulus.

When they have thoroughly determined the condition of the well, and remedied any potential problems, they can do a standard plug and abandon by setting cement plugs at several points in the upper part of the well, and testing each one thoroughly before moving on to the next.

Then they can remove the new blowout protector, gather and store away their toys, remove any debris they have left on the sea bottom, cut off the well head below the mud line and sail off into the sunset, leaving the conspiracy theorists (hopefully-in either or both usages of that word) to gnash their teeth and find other grounds upon which to sound the alarm and rally the troops..
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