April 21, 08
Davenport Power Drills For Geothermal Power 10,000 Feet Deep

Davenport Power has drilling leases in hand and the go-ahead from the Bureau of Land Management and the U.S. Forest Service to drill a series of wells to try to tap into geothermal resources. The process could take about a year, and if the company finds enough steam at a hot enough temperature, it plans to build a power plant that draws on several wells to generate as much as 120 megawatts of power, enough to provide electricity to about 100,000 homes. They plan to drill an amazing 10,000 feet into the ground using drill bits that are 17-inches wide looking for the right combination of hot rocks and water for steam generation of electricity.

The drilling began last week on Davenport’s first geothermal test well. But after burrowing 294 feet, the pipe had gotten stuck, so on Tuesday, workers blasted air and foam into the drill hole to try to free it.

“Nine times out of 10, this kind of stuff works,” said Kevin Stimson, a drilling supervisor for the project, of the foam, basically a high-end dish detergent. Workers pumped foam into the drill hole, and a mass of bubbles spilled back out of the top of the pipe, flecked with tiny bits of rock.

By Thursday morning, the pipe was almost free.

“Nervously optimistic” is how Doug Perry, the president of the Connecticut-based Davenport Power, described his feeling as the exploration phase of the Newberry Geothermal Project started. “That’s a perfect phrase.”

Searching for steam

Davenport has three different sites on the western flank of the Newberry volcano where it plans to drill a series of wells, perhaps during the span of about a year, to look for high temperatures and cracks in the rocks where hot water might be spotted.

“There’s three different (geologic) features we want to drill into to investigate to see if they have fractures on them,” said Al Waibel, Davenport’s corporate geologist. Based on what scientists find at this first spot, they’ll determine where to place the next test well.

And if the wells contain sufficient steam or hot water, Davenport could use several wells to power a geothermal power plant — it already has an agreement with San Francisco-based Pacific Gas & Electric to sell the utility up to 120 megawatts of electricity, although the plant might be built in phases, Perry said.

But first, the geologists, geophysicists and drillers have to find steam.

When the drilling rig was operating recently, it could dig down at an average of about 70 feet per hour, Stimpson said. The grinding is done by a rotating drill bit, which is turned by a mud motor. The motor is at the bottom of the hollow drill pipe and is turned, as its name suggests, by mud that is pumped down through the pipe. Once it turns the motor, cooling and lubricating the bit in the process, the mud flows back up to the surface via the outside of the pipe.

The mud also carries back to the surface the fragments of chewed up rock, which can give geologists clues about the surrounding geology.

In a trailer next to the rig, Mike Krahmer, a mud logger with Epoch Well Services, keeps track of those clues. A microscope focuses on a petri dish filled with fragments of basalt and a scrap of paper labeled “290,” which refers to the depth at which the bits of rock were found.

The basalt shows that the layer where the pipe got stuck was part of a lava flow, he said. But deeper layers can reveal more helpful information — as the appearance of quartz crystals or pyrite, for example, can signal the presence of hot water.

“As it gets deeper, they get pretty neat,” Krahmer said of the fragments.

He also monitors things like changes in the temperature of the mud and the how fast the drill bit can grind through the rock. If the drill bit speeds up, or the temperature spikes, that might mean it has hit a fracture where steam could be found.

He’ll take measurements every 10 feet, he said.

And the exploration well can go as deep as 10,000 feet into the ground, which is about as far under the surface as Middle Sister is above sea level.

It takes a lot of steel and time to drill that deep, said Perry, who said that each test well costs between $5 million and $7 million to drill.

The geologists and geophysicists have studied the rock formations deep underground and have done surface-based tests to look for areas that could have geothermal potential.

But, Perry said, “there are no guarantees.”

From the drilling site, a visitor can see the ridge trail and Paulina Peak, he said, so if a power plant is built there, people from those spots would probably be able to see it. There are also concerns that a geothermal plant would release hydrogen sulfide and other chemicals that come up with the steam, Riverwind said. He talked with people visiting the Newberry monument last summer. Many of them didn’t know about the project and were upset about it, he said.

A previous company that drilled nearby had agreed to clean up after it was done but left a sludge pond that’s still there more than a decade later, Riverwind said, adding that he was concerned Davenport would do the same.

Those issues and others need to be more fully addressed, and the public needs to be involved in the process, he said.

“When we look at the ecological importance of that area, the unique treasure that Newberry is, we’re very wary,” Riverwind said. “That may not be an acceptable location.”

But Perry said the company is supporting the BLM and the agency’s environmental analysis that was completed, and added that Davenport is committed to cleaning up the area when operations are done.

“That is certainly not the way we do business,” he said, adding that other geothermal plants have been able to blend in with their surroundings.

“They can be very low-impact neighbors,” he said.