Monday, May 03, 2010

Oil Expected To Gush From Deepwater Horizon Site In Gulf Of Mexico For Another Week; SkyTruth Calculates Oil Spill Totals Of 12.2 Million Gallons


Larger version of forecast oil spill trajectory chart available HERE; access to page on NOAA site HERE


The uncontrolled gusher spewing massive amounts of oil into the Gulf of Mexico from the remnants of the Deepwater Horizon rig is expected to take at least a week to cut off, and that is considered a highly optimistic estimate. The Coast Guard and BP have said it's nearly impossible to know exactly how much oil has gushed since the blast, though it has been roughly estimated to be at least 200,000 gallons a day. SkyTruth is estimating that as of May 1st, a total of 12.2 million gallons of oil have been spilled, surpassing the Exxon Valdez disaster. The New Orleans Times-Picayune has published a number of detailed stories on the latest developments:

-- "Gulf Coast town has little to do but wait after Gulf of Mexico oil spill"
-- "President Barack Obama talks to Louisiana fishers about Gulf oil spill disaster"
-- "Gulf oil spill phone numbers and websites are available"
-- "Gulf oil spill has our full attention, President Barack Obama assures Louisiana"

Here's a graphic which shows a good vertical depiction displaying the situation

The latest curtailment plan entails lowering 74-ton concrete-and-metal boxes into the gulf to capture the oil and siphon it to a barge waiting at the surface. The containment boxes will be 40 feet tall, 24 feet wide and 14 feet deep. This plan will take six to eight days to implement because welders have to assemble the boxes. The downside -- although this technique has been used successfully in shallow water, it has never been tried in deep water. Engineers are still examining whether the valves and other systems that feed oil to a ship on the surface can withstand the extra pressures of the deep. If it doesn't, and efforts to activate a shutoff mechanism called a blowout preventer continue to prove fruitless, the oil probably will keep gushing for months until a second well can be dug to cut off the first.

According to the Times-Picayune, teams are working simultaneously on five possible solutions to stop or at least minimize the oil spill in the Gulf of Mexico.

* Injecting dispersants at the sea floor to break up the oil.
* Closing the blowout preventer that for some unknown reason failed.
* Deploying steel boxes atop the flows to contain oil and redirect it through pipes to a ship on the sea surface.
* Installing new pressure control equipment at the well.
* Drilling two relief wells

More than 6,800 square miles of federal fishing areas, from the mouth of the Mississippi to Florida's Pensacola Bay were closed for at least 10 days on May 2nd by the National Oceanic and Atmospheric Administration. NOAA Administrator Jane Lubchenco says government scientists are taking samples from the waters near the spill to determine whether there is any danger. Fishermen have been out dropping miles of inflatable, oil-capturing boom around the region's fragile wetlands and prime fishing areas, but unfavorable weather is undermining these efforts. Alabama Gov. Bob Riley said 80 percent of the booms laid down off his state over the previous three days had broken down, and boom along other coasts is breaking down also.

What these stories don't provide is a detailed plain-language description of what went wrong. Despite rumors of sabotage or even foreign enemy attack, equipment failure is still considered the most likely cause. An individual who is an experienced professional diver and who has been on countless rigs and platforms has posted his analysis on The Tree Of Liberty Forum (begins after the jump):



Let's work through what we know...and what we think we know...so far. The BP rig was doing cutting edge drilling in extremely deep water. 5000 feet is way beyond the practical ability of divers to work, so everything is done by automated systems and remotely-operated vehicles at those depths. These are fantastic examples of technology, but their use is far less efficient in many ways than human divers. The simplest tasks often become exercises in patience, futility and frustration.

Further, 5000' is only - literally - scratching the surface of the drilling rig's work. The actual well, according to news reports, went 30,000' below the seabed. Combined, we're talking roughly the height of Mount Everest!

To date, the Blow-Out-Preventer has not been able to cease the flow and various reports indicate that the BOP had a maximum working pressure of 20,000 PSI and a gas kick of 60,000 PSI may have caused the explosion (and possibly the failure of safety systems).

I'm not a drilling expert, but did work as a commercial diver in the GOM for many years. I've been on countless rigs and platforms. Let's take a brief look at pressure:

The air you are breathing at the moment is approximately 14.7 PSI (absolute) if you are anywhere near sea level. A lot of auto tires hold around 32 PSI. The compressor at the station where you fill your tires might produce between 100 and 150 PSI. SCUBA tanks hold air or mixed gasses at extremely high pressure. Various steel tanks hold between 1800 PSI and 2500 PSI. Common aluminum tanks hold 3000 PSI. The racks of big gas cylinders you often see on a mixed gas dive job or saturation diving system often hold between 1800 - 2250 PSI. A common high powered rifle, such as a 30-06 *might* generate 60,000 PSI at the moment of firing, but even the venerable 30-06 is usually loaded at somewhat less pressure. 20,000 PSI is just a little more than what a hot .38 Special round generates.

The challenge of the leak mitigators now is to plug a hole, which may be surrounded by debris from the sunken rig, at pressures reported to be north of 20,000 PSI, sitting under 5000 feet of sea water. They can't use divers to even assist in the process at that depth. Further, 5000' is only the beginning. If the leak cannot be stopped at the seabed well head under those unbelievably difficult circumstances, they may have to drill down an additional 30,000' to plug the well from the bottom. There is no certainty that this can be done and even if it can be done, it may take an extraordinary amount of time. They're currently talking months, but we must assume that any public pronouncements at this point in time tend to the optimistic.

Now, let's look at the leak volume estimates. I believe they started with estimates of 1000 gallons per hour, then it went to 5000, then - according to some sources - 20,000 and I've recently seen estimates of 200,000. I have no more clue than anyone reading this post, but my scientifically impeccable methodology comes up with the precise figure of, er, uhhhhm... a lot!

But it all gets better...or, actually, worse. You see, no one knows with any certainty how large this oil reservoir is. It could slow and stop in a week or so, or it may, in practical terms, never stop.


What about Alaska? While no company's been told to stop work in Alaska, prospects for future Alaska offshore drilling may be uncertain. Alaska's offshore drilling projects face a lower risk of the dangerous high-pressure build-ups that may have been a big factor in the Gulf rig disaster. That's because Alaska's current offshore prospects in the Arctic are located in 200 or less feet of water. The Alaska Oil and Gas Conservation Commission regulates oil-well safety, and some of its top officials said they also hope to learn soon about the cause of the Deepwater explosion. The commission could consider new regulations, depending on what lessons are learned from the disaster. For example, the commission does not require drillers to have a second rig available to drill a relief well if something bad happens to the first rig. A couple of the commissioners said on April 30th they'd look into that matter.

Shell Oil hopes to drill in both the Beaufort and Chukchi seas this summer if it can get the federal permits it still needs and withstand legal challenges from environmental groups and several North Slope villages. But Shell doesn't have all of its authorizations yet, and federal officials have the power to cancel its project.

No comments:

Post a Comment