In mid-November, the Wah-Zha-Zhi #1-Deep well began drilling toward basement in Oklahoma’s Osage County.
It’s not going to stop.
The bottom of the sedimentary section in Osage County is at about 4,500 feet. Plans call for the well to go twice as deep.
And it’s not going to stop there, either.
“This is actually quite exciting. It’s very cool. We’re either going to learn a whole lot about basement, or we might even find something economic,” said AAPG member Kurt Marfurt, professor of geophysics at the University of Oklahoma.
Osage County recently has been home to the likes of actors Meryl Streep and Julia Roberts and even George Clooney, on site for the film version of the prize-winning play “August, Osage County.”
But now, Osage County also will be home to one of the most historic – and geologically interesting – wells in the United States.
Spyglass Energy Group in Tulsa is operating the Wah-Zha-Zhi well, drilling to 10,000 feet true vertical depth south of the town of Foraker, about 50 miles northwest of Tulsa.
“We acquired a 3-D seismic survey several years ago, said AAPG member and Spyglass Energy principal Charles Wickstrom. “In interpretation we discovered a basin with mapable reflectors below the rhyolite basement.”
Marfurt confirmed that something is there, definable by the 3-D seismic work, structurally highly deformed and with steep dips up to 30 percent.
“We see reflectors like that through several surveys of Osage County, Oklahoma. It’s clearly not a seismic artifact. It’s not a multiple,” Marfurt said.
“It could be a Precambrian sedimentary basin. It could be a volcanic intrusion, a sill,” he added. “We don’t know.”
Ultimately, there was only one way to determine what the feature is and what it might contain:
Drill a hole into it.
Wickstrom said Spyglass has chosen Native American names for several of its recent wells. “Wah-Zha-Zhi” is the original Osage language word for “Osage,” he noted.
The well should reach target depth some time in December.
“We’re going to drill with air as far as possible, but we’ll be able to switch over to a rotary mud system if necessary,” Wickstrom said.
While the idea of discovering hydrocarbons that far into basement is intriguing, Spyglass Energy has a somewhat more exotic possibility in mind.
“The attraction is really that we are in a helium province,” Wickstrom said. “We’re looking at this as a helium play that could have natural gas or oil associated with it. Or CO2. We’ll take any of the above.”
Gas produced from the shallower sedimentary sections in Osage County has shown about three-quarters of 1 percent helium, Wickstrom noted.
The attraction of helium comes from both its growing scarceness and its price. Helium prices have risen sharply in recent years, climbing past $80 per thousand cubic feet.
The Federal Helium Reserve near Amarillo, Texas, is a major commercial source of helium. The U.S. Bureau of Land Management has announced that the government’s open sale helium price for fiscal year 2013 will be $84/Mcf, up from $75.75/Mcf in 2012.
Only a handful of companies target helium production. Wickstrom said helium is used as a background gas in spectroscopic analysis of natural gas, and requires special testing to identify and quantify.
Wickstrom thinks hydrocarbon production also is a real possibility, even though the identified basin is more than 5,000 feet below the theoretical basement top. He said shale could be present as a source rock, or sourcing could come from Arkoma Basin shales.
“Downdip you’ve got Woodford Shale all over the place. I don’t think there’s a difficulty getting source into there,” Marfurt said.
Of course, if the Wah-Zha-Zhi finds oil, the crowd will go wild.
That possibility isn’t completely far-fetched, said AAPG member G. Randy Keller, director of the Oklahoma Geological Survey in Norman.
“Those images below – where the basement is – were striking. It looks like a basin down there,” he said.
“One could imagine a purely traditional play,” he added. “We have no idea what those reflectors are, but they look sedimentary.”
Keller described the shallower Osage County layers as a series of sedimentary zones that have been highly productive for both oil and natural gas. That history of prolific production extends back to discovery of the giant Burbank oil field in 1920.
“Then you get to the Precambrian basement,” he said, “which we have the bad habit of assuming is just a big layer of granite, in the most basic sense of the term.”
Production out of basement rock does occur in other parts of the world, notably offshore Vietnam and in North Africa. And wells have produced from fractured Precambrian basement rock in central Kansas.
“I’ve been studying Precambrian production around the world for several years now,” Keller said. “They just found Precambrian oil in Australia.”
A pertinent paper on the Osage County basement structures appeared in the AAPG BULLETIN in 2011, Wickstrom said. Authors were Olubunmi Elebiju and AAPG member Shane Matson, along with Keller and Marfurt.
Matson is an employee of Spyglass Energy. Elebiju was a University of Oklahoma student who now works for BP.
Their work proposed that a regional episode of extension could have occurred in the early development of the 1.4 billion to 1.34 billion-year-old magmatic province, with basin formation during that interval.
Osage County is bounded by the southern Nemaha Uplift to the west and the Ozark Uplift to the east.
“We are in a very tectonically active area. The shallow structures have been produced for 100 years. The largest structures are related to wrench-fault tectonics, all of them related to the Nemaha Ridge,” Wickstrom noted.
Spyglass Energy used a combination of seismic, gravity and aeromagnetic data to analyze the play area, he said. Wickstrom had studied the Mesoproterozoic Midcontinent Rift System (Keweenawan Rift) and understood the potential for early basin formation, but was still surprised when the Osage basement basin emerged from the analysis.
“I’ve always been intrigued by the Midcontinent Rift, and we were aware of the possibility that deeper basins could exist,” Wickstrom said.
”I can tell you, we weren’t expecting it,” he added.
If nothing else, the Wah-Zha-Zhi well should reveal significant new information about the northeast Oklahoma basement.
And then there’s the exploration potential. Geoscientists in Oklahoma are pumped, or glowing, or chuffed, or whatever word you want to use.
“As a scientist, I’m certainly very excited,” Keller said. “It’s a real wildcat thing.”