This oil is worth its salt

[peejay 327]

This oil is worth its salt

Layers of the substance in the Gulf of Mexico have hidden the crude below but energy companies are finding ways to get at it in the deepest waters.

By KRISTEN HAYS

2007 Houston Chronicle

More stands between the world's oil producers and the bounty of oil and gas beneath the Gulf of Mexico's seafloor than sediment and sea life.

It's salt.

But it's nothing like the granules in the shaker on the dinner table. It's a massive, undulating series of thick canopies, sheets and tongue-shaped chunks that stretch across the deepwater Gulf far off the coastlines of Texas and Louisiana.

Oil companies that drill in the Gulf are well acquainted with the salt layer. They have to be. The Department of the Interior's Minerals Management Service estimates up to 50 billion barrels of oil equivalent or more await discovery in the deepwater regions, offering plenty of incentive to improve already sophisticated technology used to find resources that lie thousands to tens of thousands of feet below the water's surface.

That's in addition to more than 15 billion barrels of oil equivalent discovered in the deepwater Gulf in the last 20 years.

"In a sense, this salt has hidden the oil reserves across the Gulf for a long period," said Micah Reasnor, a geophysicist for BP who specializes in new developments in the Gulf.

The Gulf of Mexico has been a major source of oil and gas for about 50 years. But the Minerals Management Service said that until the mid-1980s, drilling in the Gulf generally stopped when companies encountered salt above potential reservoirs in water depths surpassing 1,500 feet.

In Gulf waters closer to shore, where 50 billion barrels of oil equivalent have been discovered to date, drillers could find oil reservoirs between salt pillars and sheets. But in the deep waters where companies are allowed to drill, it's unavoidable.

"We didn't bother to worry about the geological regime until we had the capability of putting a drilling rig in deep water," said Barney Issen, a geophysicist for Chevron Corp. "It's been an industry march, as seismic became more capable of handling it."

Seismic imaging

Companies use sophisticated 3-D seismic imaging — pioneered by Exxon Mobil Corp. — to gather images of salt, sediment and likely reservoirs of oil.

The cost of using such technology, which requires trained eyes like those of a doctor examining an MRI of the brain, runs in the tens of millions of dollars.

Such spending is necessary to avoid wasting $100 million on drilling a dry hole, Reasnor said.

However, sound waves used in seismic imaging bounce off the salt, giving scientists an even bigger challenge in finding a usable road map to oil.

"The salt almost acts like a defracting lens, as if your glasses had bumps on them," Reasnor said. "Technology had to be developed to drill in such depths, and then imaging capability. We really don't want to have to drill hundreds of wells to find a reservoir."

Both geophysicists said salt also poses a challenge to drilling. Fluids don't move through salt the way they do through sediment, so they have to pump mud into such wells to prevent blowouts.

Spindletop gusher

The famous Spindletop gusher in Beaumont that marked the beginning of the modern oil industry in 1901 blew because it was drilled into a columnlike salt dome, Issen said.

The Minerals Management Service said the deep-water Gulf's salt layer was created during the Jurassic period, about 170 million years ago, when North America separated from what is now Africa and South America.

Basins left behind when other continents broke apart — such as offshore West Africa — also have salt layers.

Issen said the layer isn't rigid, and will move or stretch as sediment piles on top of it unlike heavier rock. He called the layer a "moving blanket kind of thing."

That motion created geometric traps and heat that help form oil within rock, so salt is a critical component in the equation.

"It's the reason we're hunting around in the first place, but it's also the first challenge," Issen said.

'Source rock'

That also means companies can't just travel past the salt layer and drill, Reasnor said.

Oil is derived from organic matter that becomes trapped in "source rock" amid layers of sediment. That matter can be dead animals or other organisms that reach the floor of a body of water.

If the heat and pressure on the source rock is sufficient, oil is formed. And salt conducts heat better than other rock.

But without those sedimentary layers, which come from sediment dumped into water from a river system like the Mississippi, there's nothing to trap source rock and essentially cook oil, Reasnor said. And where the salt ends, the layers become flat.

"You have to have structures and have to have rock buried deep enough — a rock that can contain the oil," he said. "So basically the salt is there, and you have to get through it to get to the oil."

http://www.chron.com/disp/story.mpl/headli...iz/4619494.html

[Hilarious Clinton 452]

yay US oil!!!!! Every car driver should be happy.