Friday, April 17, 2009

Piceance Basin: Learning How to Drill for Natural Gas

The tour of natural gas operations in the Piceance Basin, Colorado was a whirlwind one. It was organized and paid for by the American Petroleum Institute and there were about 11 of us bloggers and traditional media in attendance: Brad Jones (Face the State), Bob McCarty (Bob McCarty Writes), Andy Kear (The Oil Drum), Tim Hurst (Red, Green and Blue), Judith Kohler and David Zalubowski (Associated Press, Denver bureau), Dennis Webb (Grand Junction Daily Sentinel), Josh Nichols (Grand Junction Free Press), Guntis Moritis (Oil and Gas Journal), Susan Klann (Oil and Gas Investor).

Not knowing much at all about natural gas, this was quite an education for me. And I’ll admit, some of the technical drilling and geological information was Greek to me but everyone was patient enough to put the processes into layfolk terms for those of us not schooled in natural gas technicalities.


The tour was hosted by Williams Companies, the largest natural gas producer in Colorado, with other operations around the country. The Piceance Basin (pronounced “Pea-aunce”), where I was, has one of the biggest accumulations of natural gas on the entire continent. Williams is also one of the most technologically advanced producers. They were the first to apply offshore drilling technology to land for some of their operations – specifically, “S” shaped drilling that allows for up to 16 natural gas wells to be drilled from one rig, compared to the traditional four wells. It also means a smaller footprint, using 75% less surface than traditional methods of drilling.


How natural gas is drilled

A rig is used to drill natural gas wells - the one we saw uses a 6½ inch pipe to hit a natural gas well 7,000 - 8,000 feet underground and fifty feet in diameter . The rig we toured is also able to “skid” – move forwards and backwards, side to side – on tracks. This allows the rig to drill many wells and in an “S” shape. That is, the rig doesn’t drill straight down, but drills at an angle for about 1,000 feet or so and then down another approximate 7,000 feet to the natural gas reserve.


It takes about two weeks to drill a 7,000 foot well, and then another few weeks to get all the equipment for extracting and cleaning the natural gas up and running.

Controlling the rig:


A worker ads another length of pipe to complete the last few hundred feet of an 8,000-foot well:


Next, Williams pumps cement down the well, which fills up and around the outside of the pipe casing. Then what takes place is a process called “fracing” (no, it’s not what you Battlestar Gallactica nerds think it is…)
.

Fracing is what a company does to create fractures in the natural gas well. A line with an explosive is dropped down the well and the charge is set off, perforating the well and the cement casing, fracturing the surrounding “zone.” Gas is then freed up to enter the pipeline from many paths in the zone and carried to the surface.


Fracing has been a controversial process, as there are chemicals and large amounts of water involved that are pumped into the well after the explosives are set off. Williams told us that there is a very small amount of chemicals used compared with the amount of water pumped down the well. One chemical is like a soap, the other is a lubricant, another is a bug killer (likened to what you would use in a pool to keep algae away), and other is a cleaner (likened to what is used in a wastewater treatment facility). Also pushed down the well are sand particles ("proppant") that will hold open the cracks in the sandstone caused by the explosives.

The water used to pump these materials down comes back up the pipe under its own pressure. That water is then dumped into a holding pond like the one below and reused on other wells:


In other areas of the country like Wyoming, companies use diesel in the fracing process and there have been concerns about ground water contamination. Williams explained that in Colorado, diesel is not used in fracing. Furthermore, the potable water in the area only goes down about 400 feet and fracing begins around 5,000 feet.


The well site we toured is expected to produce for 30-40 years.

It should be noted, too, that Williams made it very clear that the rig we toured was a state-of-the-art, super-efficient machine. Not every natural gas operation is like this. Every well is different, every company is different, and while the general processes may be similar, the technology and use of materials will vary.

Stay tuned for next posts: What happens after a well runs dry and the recycling of waste heat/CO2 at the gas plant.

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