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2010 Oil Spill Answers (Pt. 1) May 3, 2010

Posted by Jamie Friedland in Offshore Drilling, Politics.
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Since the explosion on the Transocean Deepwater Horizon rig in the Gulf of Mexico, many people are trying to understand what happened.  Traffic to this page has spiked significantly because I recently wrote about the dangers and strong cases against offshore drilling in general.  But I have not yet addressed the current crisis.

This post and those to follow shortly will explain what has happened and is happening.  Below, you will find basic questions about this disaster and answers to them.  I will add additional questions and answers later today, but I want to get this out as soon as possible.  If any of you have additional questions, please add them as comments and I will try to address them.

These are the questions answered below:

  • What was the oil rig doing?
  • What caused the explosion?
  • How much oil is spilling?
  • Where is the oil spilling from?
  • Can we stop the spill?  How?
  • Could the spill get any worse?

What was the rig doing?

The oil rig in question was drilling an exploratory well called “Macondo” to see if that site could be used for large, commercial-scale production.  Signs were promising, and the attempt was soon to be labeled a success.  That has changed, but the site will definitely still make it into the history books.

This was a deepwater operation, even riskier than shallower “normal” offshore drilling, but at this point, the world’s oil companies have tapped all the easily accessible resources.  At that site, the ocean floor was nearly a mile beneath the surface.  The oil formation was another 3 miles underground.

What caused the explosion?

The exact causes have yet to be determined, but educated guesses can and have been made.  You may recall old time footage or photos of oil geysers shooting into the air after big oil finds in Texas.  Many oil formations are pressurized such that if a drill pierces the geological formation, the oil escapes under its own power.  This is a cheap way to get oil out of the ground since it comes up on its own.  Rigs like the iconic grasshopper oil derricks you may have seen around the country must be used if the pressure is not high enough.  For offshore drilling, the pressure is always high enough.

Anything that lies 4 miles beneath the surface of our planet exists at very high pressures.  To visualize this, imagine a huge, full water balloon encased in a block of cement.  Imagine that cement casing fits so tightly, that the balloon is squeezed beyond the bursting point but is unable to release its water because the cement is solid and there’s nowhere for the water to go.  Now imagine somebody drilled into the cement block.  When that drill pierced the chamber with the water balloon, that water would shoot back up through the tunnel the drill bored.  Depending on the pressure involved, it might do so explosively.

In the case of this oil rig, we are dealing with pressures that are hard to visualize.  What is less difficult to visualize is that instead of water, this rig had pierced a balloon full of highly combustible oil.  Furthermore, the company had been warned that this reservoir likely held pockets of volatile natural gas.

The exact cause is unknown, but we do know that in a matter of seconds, a huge blast of oil and gas shot up through the 4 miles of pipe and shot clear through the floor of the rig.  One spark lit all that fuel and suddenly the Deepwater Horizon was engulfed in a massive fireball. Drilling Ahead has a well informed and richly presented explanation of the ordeal those workers went through.

The state-of-the-art Deepwater Horizon rig goes up - and then down - in flames.

How much oil is spilling?

The ongoing oil spill in the Gulf of Mexico is worsening at an exponential rate.  BP’s initial lowball figure (and likely lie) pegged the spill rate at 1000 barrels/day. 1 barrel = 42, gallons, so 1000 barrels/day = 42,000 gallons/day.  Government officials examined the data and quickly realized that the rate was more like 5,000 barrels/day (210,000 gallons).  Since then, the spill pattern suggests that the rate is increasing rapidly.  On May 1st, experts determined that the oil could be spilling at a rate of 25,000 barrels per day (1.05 million gal/day). Unfortunately, this is only the beginning and this catastrophe stands to get far, far worse (See “Could the spill get any worse?” below).

Where is the oil spilling from?

It appears that there are three leaks: 2 from the crumpled remains of the pipe that ran from the ocean floor to the rig at the surface, and one from the point on the ocean floor where the subsurface pipe connected to that pipe that rose through the water.  It is this third site that presents the greatest problem.

Where the pipe meets the ocean floor, there is a giant valve called a “blowout preventer.”  In the event of a gusher or other dangerous, high-pressure event, the valve clamps shut, protecting the rig.  It is built with many redundancies as the last line of defense against this very kind of event.  Somehow, that valve failed, and is still leaking a high volume of oil from the reservoir.

There are 2 efforts underway to stop the spill. One has failed; the other will take months. Image Credit: Times/Picayune

Can we stop the spill?  How?

This is the question that makes this situation so dire.  A crashed oil tanker like the Exxon Valdez has a limited amount of oil that can spill.  A tapped reservoir like this has massive amounts of oil to release – it is estimated that this block could contain as much as 100 million barrels (3.1 billion gallons).  As the diagram above demonstrates, there are 2 efforts underway to stop this spill.

1)   Remotely operated submarines are attempting to engage the blowout preventer.  So far, they have been unable to do so.

2)   Another rig has moved into place to build a “relief well.”  To do this, it must drill down to the ocean floor, through the 18,000 feet of sea floor, and then they will attempt to drill into the subsurface pipe laid by the original rig.  If they succeed in doing that, they can stop the oil flow.  But this could take 2-3 MONTHS.

3) A final approach is to build a kind of dome to place over the spill site to funnel the oil up where it can be collected.  This has only been tested in shallow water.  As oil companies and the rest of the world now know, deep water is a whole different ball game.

If the current estimates are correct (and don’t get worse), within 2 months this spill will dump 6 times as much oil as was spilled by the Exxon Valdez.  In 3 months, there would be nearly 100,000,000 gallons of oil floating in the Gulf of Mexico, if not beyond.  And that’s assuming this spill rate doesn’t get continue to increase.

Could the spill get any worse?

Yes.  The blowout preventer isn’t closing like it is supposed to, but it is creating an artificial bottleneck and reducing the amount of oil that can escape at a time.  However, there is concern that behind that valve, the high pressure is circulating a mixture of water, hydrocarbons, and sand.  That sand is moving with considerable force and may be scouring the area behind the valve.  If a part of the valve or the support structure were to give way, the rate of the spill could increase by several orders of magnitude, experts say as much as 150,000 barrels/day (6.3 million gallons).  That would be an Exxon Valdez EVERY TWO DAYS.

More answers to come.  Check back later today and as this crisis develops.