Kate Mackenzie The new cap heralds a test for BP’s well casing

BP share price 5-day chart

BP announced a few hours ago it had successfully placed a new capping stack over the lower marine riser pipe (LMRP) of its gushing Gulf of Mexico well, Macondo.

Investors, who have in the past week rewarded the company’s improved oil capture and new cap plans, are impressed, with shares more than 2.5 per cent higher in early morning trade.

Oil continues to flow from the well at pixel time (see image below right). Although the caps have been placed, their valves have not been sealed. BP will attempt to close them today, as a way to test the integrity of the entire well.

As the FT noted earlier this week, BP’s second-quarter results presentation on July 27 will be a pivotal point for the company.

But another sort of test is due sooner. BP’s statement says a “well integrity test” will begin today, now that the new cap stack is fitted. And closing the cap is actually part of it:

For the duration of the test, which will be a minimum of 6 hours and could extend up to 48 hours, the three ram capping stack will be closed and all sub-sea containment systems (namely, the Q4000 and Helix Producer) will be temporarily suspended, effectively shutting in the well. It is expected, although cannot be assured, that no oil will be released to the ocean for the duration of the test. This will not however be an indication that flow from the wellbore has been permanently stopped.

What are they testing? Well pressure, according to the latest briefing from BP’s Doug Suttles:

“…the purposes of the integrity test is to determine if we believe we have the flow contained within the casing of the well. So in this particular case, if we see high pressures it’s a good sign. It actually means that the flow and the oil is fully contained in the existing well.

And if not?

“If we see low pressures, then that would indicate that potentially oil is escaping out of the casing at some point. So in this particular test what we’re hoping to see is full shut in pressures. Which would indicate that the casing’s intact.”

So there is a hint that if the new cap might remain successfully closed for some time (though BP does reiterate that the relief wells “remain the sole means to permanently seal and isolate the well”).

However an anonymous technician quoted by the New York Times believes that keeping the cap sealed will probably be too risky; even if the pressure tests indicate good wellbore integrity:

“Do I want to make that bet that there’s sufficient inherent strength in that well path to keep that well contained?” said the technician, who spoke on the condition of anonymity because he was not authorized to comment on the work. “Why would we take that chance?”

Either way, BP says that if the cap cannot remain closed, it will simply resume its various efforts to improve the collection of the oil and gas spewing from the well.

Related links:

The Oil Drum latest discussion thread
BP’s Kent Wells’ technical briefing video – installing the 3 ram capping stack