Deepwater well control: where's the fire?

True test will come with blowout, but practical solutions are available

William Furlow
Contributing Editor, Houston

Some of the biggest names in the business - Wild Well Control, International Well control, and Cudd Pressure Control - just shake their corporate heads when the subject of ultra-deepwater well control comes up.

"As far as I'm concerned, it's like drilling on Mars," said Brian Krause, president of IWC.

"The true test is going to happen when the first ultradeep subsea blowout occurs," said Peter Atkins, manager of special projects for Wild Well Control.

"Nobody has any real answers," said Steve Mayo, director of business development for Cudd Pressure Control.

Like all operations at the leading edge of technology, it is going to be very expensive to find out how one fights a blowout more than a mile below the ocean's surface. The dilemma is not a matter of fighting a fire on the surface, but of capping and controlling the spill at the seabed.

Mayo admitted his company does not have all the answers when it comes to ultradeep subsea. "We're like everyone else," he said. "Nobody has any real answers, but the industry has come together as a whole (in recognition of it)."

Ultradeep environment

What makes these well blowouts different from all the rest?

Ultradeep wells are usually located in remote and hostile environments, such as West of the Shetlands or off the Continental Shelf of the Gulf of Mexico.
There is a very limited number of rigs available to drill such wells and the likelihood that one would be available for drilling a relief well or other well control activities is remote when utilization is 100%.
The research into a deep water solution is so costly that only a collaborative effort by the major oil companies, or their governments, could afford to come up with the capital. Unfortunately, most experts believe the real test will come when the first of these ultradeep blowouts occurs. Atkins said he believes the first of these blowouts will be in the Gulf of Mexico, where experienced crews are spread thin and ultradeep exploration is booming.

The experts agree on one other point - they all want to be there when the first such event occurs.

Practical solutions

Amongst the apprehension and hype of ultradeep well control, Larry Flak, engineering manager for Boots & Coots, now owned by IWC, said he has some practical solutions that should put operators minds to rest.

Flak agreed that ultradeep well control offers some unique challenges, but also offers some advantages over conventional subsea well control. From his point of view the trick is to think outside the box. "How can I kill a well at 10-15 bbl per minute? You don't," he said.

Rather than using traditional dynamic kill methods, which requires pumping at a very high rate, and injecting a massive volume of fluids with very powerful pumps, Flak advocates using reactive fluids that solidify quickly, requiring less volume, and avoiding the prohibitive friction pressure of high volume conventional fluids.

As far as an alternative rig to drill a relief well, Flak said operators have established a verbal agreement that whichever rig is best able to shut down and move on to assist with the relief well will do so. This may not be the nearest rig, but it will be a rig capable of drilling in ultradeep water.

Blowout flow offset

A second option, that takes advantage of the ultra-deepwater column would involve plugging the blowout from the existing rig. Flak said these blowouts would have two distinct advantages over blowouts in conventional water depths:

There is a tremendous hydrostatic column putting pressure on the formation and choking down the flow of oil. This means the blowout will spread more slowly.
The more dramatic advantage is the great distance the oil condensate will travel before reaching the flash point, at which the explosive natural gas drops out of solution. It is this gas that makes a subsea blowout so dangerous.
If the gas collects under the rig then a catastrophe is imminent. This generally leads crews to abandon platforms or rigs immediately and is often the cause of explosions at sea and massive loss of capital investment and production cash flow.

Flak said the condensate will drift so far during its mile-long rise to the surface that by the time the gas is released it will be safely clear of the well site. In such an event, the rig could hang the drill pipe and riser, move off the well, wait to see where the oil and gas surface, then return to try and remediate the blowout by moving the drill pipe up and down or pump the kill fluids down the drill pipe.

Using one of the "A-B" dynamic gel mixtures means the rig itself could carry enough chemicals on the deck to kill the blowout.

"You don't have to mix large volumes of them," Flak said.

The lower volume needed with these dynamic fluids means using the rig's drilling fluid pumps and a few skid-mounted stimulation pumps. The large fluid pumps already in place on ultradeep class rigs is another advantage that can be brought to bare in a blowout situation.

Flak said the downside to this method is the volatility of these reactive chemicals. If they mix anywhere but in the blowout wellbore, such as at the surface plug flow line, it will cause serious problems. Also residual materials may remain in the drill stream posing a threat if they are allowed to mix.

But even with these caveats, Flak said he believes the situation is much less dramatic after thought is given to the natural forces that affect blowout plumes and the blowout fighting resources already available at the drill site.