Discussion: Gulf Oil Disaster only the beginning?

Just when you thought all the figures and photos coming out of the gulf of Mexico weren't scary enough... articles are now homing in on the possibility this may be the harbinger of an even greater gulf (and possibly global) disatser.

First - some science background. Yes, you heard me...

I'm going to talk about methane... (cue jokes about me talking 'a load of hot air' but anyway...). It's the centrepiece of this blog, and I think before I do it may be important to briefly cover the basics of what it is and what's normal about it in the oil extraction process.

Oil and natural gas (including methane) are both created in the same general process, when organic matter is buried in sediments millions of years ago, and gradually compressed as layers continue to be deposited on top of them. If the conditions are right (anaerobic organisms being present) the organic matter eventually turns into methane, which becomes trapped if the rocks above it are impermeable, ie impassable.

A picture that shows rock grains (called
reservoir rock) with oil trapped between
each grain - this pic and more info from here

If the methane passed through permeable rocks and then got trapped by impermeable ones above them, then the methane is trapped in these rocks and eventually becomes oil. As a result, oil is usually found trapped between sedimentary layers, with a layer of methane on top. It is therefore extracted along with the oil, and the flame often seen on oil rigs is this methane being burned away.

As discussed in the text above, oil is usually found trapped between sedimentary layers, with a layer of methane on top - this pic and more info from here

So, methane and oil are closely connected and both part of the oil extraction process. In normal deposits, oil deposits contain about 5% methane.

Now back to why this is important...

Because current measurements indicate the oil emanating from the gulf contains about 40% methane...

Hints appeared earlier in the month, after fieldwork by Samantha Joye in the area of the rig discovered methane levels 10,000 times above background levels in a plume emanating from the site. This was updated this week when this article in Reuters reported that "as much as 1 million times the normal level of methane gas has been found in some regions near the oil spill." This comes from the work of an oceanography professor, John Kessler, who's just come back from a 10-day research expedition taking water samples at the surface and about 8km depth in the vicinity of the wellhead in the Gulf.

The presence of methane, and the microbes it attracts, acts to essentially completely neutralise all oxygen in the water - killing all life that may be present. Kessler's investigation showed a sporadic depletion effect in the area, in some places as much as 30% whist other areas were barely affected. He concluded that these depletion levels were currently not critical, but if the oil (and gas) continued to spill into the gulf at that rate then there could be serious consequences for the life there.

This is not, however, a discussion on the current impacts of methane. They make another addition to the lethal processes occurring in the gulf as a result of the oil spill - for example I've discussed the oil plumes at depth and the deadly consequences of the dispersant they've been using in an earlier blog.

So what's the big deal then?

The greater implication seems to be what these higher levels of methane are actually indicating. From what I've read this might be the equivalent of everybody worrying about the earthquakes on a slope of a volcano, when they're actually a sign of the much more serious eruption soon the follow.

According to the Helium Earth Sciences blog, the location of the Deep Water Horizon rig was criticised over a year ago as an accident waiting to happen. Measurements had proposed the area contained a huge subterranean reservoir of methane, between 15 and 20 miles across. At that depth it has been calculated to be under pressure of roughly 100,000 psi (per square inch) - which current engineering technology cannot actually yet contain.

The Horizon was sunk when a methane gas bubble at the wellhead exploded upwards and the BOP (blow out protector) on the rig failed to clamp down as it should. But this may simply be a precursor of a deeper issue, indicated by the cracks and fissures recently appearing on the ocean floor - that the horizon has poked a hole into a rather dangerous balloon and the pressure is releasing through this new hole...

If this bubble bursts, it will "erupt with an explosive fury similar to that experience during the eruption of Mt. Saint Helens", depleting the oxygen in the water it touches, sinking all ships in it's blast radius and causing devastating tsunamis across the Gulf region. This is not an unknown phenomena - it has been proposed to have caused heating of the Earth, mass extinctions in prehistory, and even theorised to be behind the disappearances of ships and planes in the Bermuda Triangle.

So if those fissures that have been seen really are a precursor for something bigger, we could all be in trouble... we need to pay attention.