CARBON CAPTURE:

Wyo. wants more carbon dioxide

MIDWEST, Wyo. -- Eight years ago, the Salt Creek oil field here was pretty much played out. It was a forest of rusting oil rigs, immobile pump jacks and a tangle of electric lines that powered them. Every day, Salt Creek was using more energy to extract less oil out of the ground. There were estimates that this century-old field -- once one of the richest in the Rockies -- would be out of business by 2015.

But then Anadarko Petroleum Corp., a Texas-based oil exploration company, moved in and plunked down $265 million to buy the company that owned the field. A few months later, big refrigerated tank trucks began showing up next to wells that were still producing. The trucks contained the magic ingredient that, when pumped down under pressure into one well, began to push up more oil into nearby wells.

It was carbon dioxide, basically an industrial waste purchased from an Exxon processing plant in Shute Creek, Wyo., where it was being separated from natural gas and vented into the air. Anadarko's experiments looked so promising that it built a 125-mile pipeline to bring in more CO2. Since then, it has pumped more than 10 million tons of CO2 into the ground, and the company now estimates that Salt Creek's production will last until at least 2050 and yield 800 million more barrels of crude.

What started out as an experiment, according to the company, is now the biggest carbon storage project in North America. Its results have rocked Wyoming. State officials, who estimate Wyoming supplies about 10 percent of the nation's fossil fuels -- including a third of its coal -- had been worrying about the potential impact of federal greenhouse gas regulations. Anadarko had demonstrated how it could produce what it calls "green oil" by burying a large amount of man-made greenhouse gas.

Basically, the company calculates, it is injecting 5,000 to 8,000 cubic feet of CO2 into the ground to produce a barrel of oil, which produces about 8,000 cubic feet of atmospheric carbon when it is burned. Thus, Salt Creek's oil is now "60 to 100 percent carbon free."

While environmental groups here are still chewing over that one, the message of getting perhaps as much as 800 million additional barrels of oil from what was thought to be a geriatric field began to resonate with businessmen and lawmakers: If "green oil" was achievable, why not "green coal"? As other oil producers quickly snapped up all the remaining CO2 supplies in the state, officials in Wyoming, which gets almost 70 percent of its income from fossil fuel production, began scrambling for ways to get more CO2.

An influential joint committee of state energy experts and business leaders issued a report in 2006 that concluded that CO2 injections could bring up as much as 1.2 billion barrels of oil in the state. It said the most likely source for generating the extra CO2 would be new coal-fired power plants equipped to separate CO2 from their emissions. For Wyoming, by far the nation's biggest coal producer, that was a very popular solution.

Rick Robitaille, a spokesman for Anadarko, notes that there is nothing terribly new or controversial about using CO2 to push more oil out of wells. The United States leads the world in this technology, and Texas companies have been using it on smaller-scale projects since the 1970s. "People had talked about using CO2 in Wyoming for years, but we're the ones who actually went out and did it."

And some of the company's success, he admits, was due to timing, not technology. "When we started this, oil was selling for $20 a barrel. When it hit $60, we looked like geniuses."

Following the tracks of the 'boomers'

The Salt Creek field produces a very high-quality crude oil. It was so light that it was first used to grease the axles of covered wagons heading west, and later, still unrefined, it was used to lubricate steam engines on railroad trains. It provided the fuel oil for the Navy in World War I.

In the 1920s, when automobiles boosted demand, producers regularly sprayed gushers over the salty topsoil here in their frenzy to bring in more production. Thousands of people came, making Midwest a work camp for those who worked in the oil fields. The locals here called them "boomers" because they shared the idea of getting rich quick. Among them were the "nitro-shooters," men who, for a fee, would dump 100 or more quarts of nitroglycerin down a well and then detonate it to further increase production.

Sometimes, according to Ed Billie, a local historian, they literally went BOOM, and their trucks would "vanish in a cloud of smoke." There were lots of other ways of making money, noted the historian, who explained in his book about the early days at Salt Creek that the field attracted "a substantial number who regarded drinking, fighting and courting 'ladies of the evening' as matters of distinction."

A refinery was built and a pipeline was constructed to send gasoline to nearby Casper. It had to be patrolled, Billie noted, because at night, "oil hijackers" would dig up the line and drain off the product in 50-gallon drums.

There was so much natural gas coming up with the oil that producing companies didn't know what to do with it. So they sent it up a pipe and set fire to it, creating a nighttime phenomenon that a local historian called "The Big Torch." It created a lovers' lane where local teenagers would park their cars and spoon under the plume.

From a geological point of view, the 9-mile-long field became a gigantic pincushion with as many as 4,000 wells drilled into the cap rock, or the impermeable layer of rock and sediment that usually covers an oil reservoir. Any of the old wells could leak the injected CO2 back into the air, where under certain conditions it can be deadly. That posed a major technological challenge for Anadarko.

The mysteries and dangers of old wells

The company set out to plug most of the wells. But just where they all were was unknown; the records had long since been destroyed. The company flew aircraft over the field equipped with Department of Energy devices initially designed to hunt for enemy submarines. They were looking for the wells' telltale magnetic signature: metal pipes extending vertically into the ground.

But during World War II, the company discovered, many of these pipes were extracted and sold for scrap. The holes were stuffed with old telephone poles and other rubble, making finding and sealing them that much more difficult. Anadarko designed a tool with a corkscrew-like fitting that reached down into the holes and fished out the poles so the old wells could be sealed with cement.

There has been a "huge amount of work" done to identify what CO2 does when it reaches some 2,500 feet or more underground, where it enters the porous rock formations that contain the oil, according to Franklin Orr, who teaches petroleum engineering at Stanford University. When oil fields age, they lose the pressure that creates gushers, so starting in the 1960s, oil companies began injecting water into the Salt Creek field to push up more oil.

But during the 1980s, production began a long decline until Anadarko began injecting its CO2 into selected wells. Underground, CO2 functions as kind of a solvent that can mix with the oil and detach it from the porous rock formations where it is trapped so it can flow out and upward into nearby wells. Because it flows much more readily than water, "it [CO2] can go places more easily and quickly than water," noted Orr.

However, if it leaks to the surface, there is the possibility that it can accumulate, because CO2 is heavier than air. "If it's a cold night and it's down in a hollow, it can be deadly," the scientist added, because it can cause suffocation.

CO2 means jobs and money

So far, according to the company, CO2 leaks have not been a problem. Anadarko workers continue to hunt for old wells, some of which have been found under houses and streets here. "Safety is one of the criteria on which this company is evaluated," explained Craig Walters, Anadarko's regional manager. The company has gone door-to-door here in Midwest (population 300) and in the neighboring town of Edgerton (population 100) to explain the risks.

It has also installed CO2 monitors in the field and given employees working there monitors that would set off an alarm if there were a lack of oxygen. Anadarko has also set up a medical evacuation unit and trained teams of its workers to deal with cases of oxygen deprivation.

So far, there haven't been any serious leaks, according to the company and local residents, many of whom work for Anadarko. But there are some suspicious bubbles coming up from the bottom of Salt Creek, near where Frank Shepperson, a local rancher, grazes his Black Angus cows. He said he has alerted Anadarko, and company technicians are hunting for the source.

Shepperson, a former world champion calf roper, said he thinks the terrain around Salt Creek is too flat and too windy for CO2 to collect. "They're good neighbors," he says, referring to Anadarko. Since the company has removed many of the old oil rigs and pumps, he's seen ducks and eagles returning to what once was a big, messy industrial site.

The second Salt Creek oil boom is much quieter than the first. Much of the new production equipment is automated. Shepperson has a few CO2 pipelines crossing his land and some wellhead fittings that vaguely resemble fire hydrants. As the gas reaches the big injection pumps, you can hear the CO2 hissing through the valves. To Anadarko, it is the sound of money. Shepperson explained that he is a big supporter of CO2 injection because it has brought jobs back to this area and could bring more.

Despite all of the fuss over man-made CO2, the rancher, like most people here, finds it hard to believe that global warming has human causes. "Nature is too powerful for man to overcome."