Gulf of Mexico Environmental Disaster: A Subsea Blowout Not Oil Spill, And Other Hard Facts

A commentary by George H. Croy, author of "The Energy Trail - Where It Is Leading"

Singapore, 26 July 2010.  Much has been said, even more has been written about the oil leak in the BP well off the US Gulf coast, mostly by people who have little or no experience in the oil industry, leading to a lot of misconceptions. People talk about ‘Doomsday Events’, the ‘End of the World’ and such like. These are the ones that should be ignored. Especially these people. Like CNN’s Anderson Cooper. You cannot make realistic comments when you know nothing to begin with, or have a few choices phrases picked from news media - whose job it is after all, to sell papers. Sensationalism sells newspapers. The truth has little to do with it.

Knowing the truth however puts things into a completely different perspective. In the first place, it was not a ‘Spill’. A ‘spill’ suggests something preventable, an error of judgment, a mistake in calculations, something like that. When you are driving down the road and all of a sudden you run over something and your tyre goes ‘bang’, you don’t call it a ‘spill’, you call it a ‘blowout’, right? Well, what happened in the Gulf was a subsea blowout. There is a world of difference between a spill and a blowout.

When oil companies drill into the earth in search of oil and gas, they know roughly what to expect. A hundred years ago, our ancestors didn’t know what to expect and there were frequent blowouts with fire, lose of life, widespread pollution. But they learned, and refined the drilling process to the stage that today’s drilling and completion industry uses highly sophisticated technology every step of the way to ensure the safest possible conditions.

The Deepwater Horizon was an ultra-modern, ultra-deepwater drilling semi-submersible. Built in 2001 by Hyundai in Korea, it was on long-term lease to BP to drill some of the deepest holes in the oil industry. In 2009 it drilled the deepest hole in history when it completed the measured depth Keathley Canyon Block 102 well of 35,055ft (10,685m), a total vertical depth of 35,050ft - in other words virtually straight down - in a water depth of more than 4132ft (1259m).

In April, while the rig was drilling another prospect, this time in 5000ft of water (1500m), an explosion on the rig caused by a blowout set fire to the rig and killed eleven people. This was on 20 April. The fire raged for two days before the rig finally sank, releasing the oil and gas into the Gulf waters. The blowout came from the marine riser, a large pipe suspended between the rig and the seabed blowout preventer (BOP), used for containing or handling drill pipe, hydraulic and telemetry lines.

It appears that the rig had just finished cementing in the bottom hole casing or liner. They had circulated out the remainder of the cement and the drilling mud and replaced them with seawater. This is not the best of conditions to be in, as the open drill pipe is an invitation for pressure to escape. They also waited 20 hours for the cement to set. All this is consistent with the path towards a blowout, as the reservoir has a high gas/oil ratio.

The well is filled with drilling mud which is heavy enough (in this case, about 14 pounds per gallon (lb/gl) – water is about 8.3lbs/gl) to hold in the reservoir contents until the liner can be cemented. Cementing the liner, a 5-ins or 7-ins diameter piece of pipe, requires specialised cement, pumped by highly sophisticated pumps down through the drill pipe and liner, round the bottom of the liner and up the annular space between the liner and the rock face.To prevent damage to the rock face, the cement is frequently lighter than the drilling mud.

Not much information on this has been released, but it is realistic to surmise that the cement was nitrified (had nitrogen gas injected along with it to lighten the weight of the cement), and the lighter weight allowed gas to migrate into the wellbore. Gas built up in the wellbore and finally blew the seals on the BOP and headed for the rig floor where it erupted like a geyser before exploding.   

All the facts may never be known for sure, but much will come out in the wash when in-depth investigation take place but one fact would appear obvious, that a fault in the BOPs prevented them from being closed. Not only that, it appears that gas successfully migrated up the outside of the well casing. That’s what cementing is supposed to prevent. It’s one of the cheapest commodities in oilfield supplies and yet it appears that they skimped on their cement jobs, with insufficient sealing around casing crossovers and micro-annuli (where the cement does not seal to the casing because it shrinks during setting), allowing gas to migrate up to the base of the BOP.

The ensuing fire caused the rig to sink, dragging with it the riser and drill pipe, back to the seabed. The blowout then was released into open water. The work done so far in trying to mitigate the disaster should not be belittled in any way. What went before is irrelevant. All will be dealt with in due course. What happens now is what is important. Just imaging trying to thread a very fine sewing needle - from ten feet (3m) away – that’s the level of challenge facing the people trying to get this blowout under control.

Environmental damage

A lot is being said about environmental damage but, in reality, it is not the worst oil spill there has ever been. Sure, it brings with it the anguish of seeing wild creatures suffocated or poisoned by it, lots of people have lost their livelihood where fishing has been devastated. But this Earth has been oozing oil from its pores since time immemorial, much more than is now threatening the shores of the Gulf. The biggest source of oil pollution is not tankers pumping overboard their waste during tank washing, or fishing boats pumping out their bilges, or rigs, or subsea blowouts, it is oil seeping from fissures in the seabed. And this has been going on for millennia. And the oceans survive.

 The oil from the Gulf blowout will decay over time. It will break down. There are creatures that will feed on it, there are bacteria that will consume it with glee. In the face of what has happened this is a monumental disaster for the people of the Gulf, especially those who rely on fishing beds for their livelihood. But on the grand scale of things it isn’t such a big deal.

The Americans continue driving their SUVs and gas guzzling monsters even as they squeal ‘Foul’. They didn’t utter a word as the production facilities to provide the gasoline to drive their vehicles plundered and polluted other areas of the world, like Indonesia, Burma, Thailand, Vietnam, Philippines, South America – anywhere that oil could be found. Where were the American cries of horror at the mess that was being made of other countries? It’s only because it is at their own front door that they have suddenly become so vocal.

If CNN’s Anderson Cooper had visited those other lands, seen the devastation caused and ‘Kept them honest’ like he says he’s doing now, maybe we could have more sympathy for his present efforts. But my advice now to the people of the Gulf is just to sit tight and wait. Your time has come. It’ll clear up eventually. And then you’ll understand what many of the rest of us have had to put up with for more than half a century, except we got no compensation from the oil companies, or the governments.       


Other articles by George H. Croy on Gaia Discovery:

Part One - The ABC of Energy: What is Energy

Part Two - The ABC of Energy: The Definition of Energy

 Part Three - The ABC of Energy: Energy Sources