From “Ten Ni Michiru Seimei,”
NHK Publishing, 2001

Background: The first episode of the Space Millennium series on NHK TV looks at how the earth — evolution has been affected by comet and asteroid impacts. As field producer, I scouted the story of the Ames crater — a site in Oklahoma where a 400 million year old impact almost 2 miles underground turns out to be a perfect collection point for oil. Photos are my own. — CF

In Northwest Oklahoma, huge farms stretch out to the horizon. Buried under this agricultural belt is one of America’s biggest single oil deposits: the Ames oil field.

At 14:20 hours on June 16, 2000, crude oil spurted vigorously from an oil well which had been more than three weeks in the digging. The quality of the oil was immediately checked using a centrifuge: 99% pure. This was very high grade crude.

The Ames oil field is new; full-scale extraction started in the 1990s. Why was so productive a field ignored until the end of the 20th century in the State of Oklahoma, where oil well development has been hotly pursued since 1928?

Almost 100 oil wells have been now been dug in the Ames field. Plotting the positions of these wells reveals an interesting circular pattern. And this latest well, too, fits inside the ring. Why are the wells arranged in this way?

A 3 dimensional representation of the crater as it would look if almost 2 miles of sea sediment which bury it could be removed. Data comes from well logs, courtesy of Continental Resources, Inc.

All-out construction of new wells at the Ames site really got going in 1991, after an oil well known as the Gregory came on line. Until the Gregory, the only oil extracted in this region was from shallow accumulations. Capillary wells were used, with very low production volumes. Deeper down in the Ames area was known to be very hard granite — not a place where anyone expected to find oil.

The drilling of the Gregory was a stroke of luck. In fact, there had been a well here before, but it had petered out and been ignored for many years. However, [oil geologists] were finally beginning to understand the area’s underground structure. Based on this data and his own winning instincts, Harold Hamm — president of Continental Resources, a local company which owned the rights to the Gregory — began to think there might be oil deeper down. He ordered a test well dug to find out.

CF interviewing Harold Hamm,
developer of the Ames crater oil field

Until that time, it was common knowledge that a thick layer of granite lay at about 9000 feet (2750 meters) below the surface, which would make drilling very difficult. But the rock-crunching drill bit advanced like a hot knife into butter even after penetrating the granite. Strangely, it seemed that this underground rock had been finely pulverized. And then the drill passed into a deeper granite layer, which was brimming with oil. What was going on here?

It’s mostly in the movies that oil rigs strike a gusher; it wasn’t supposed to happen this way. But because of the massive dislocation and settling of blocks underground, local pressure at any given point over the crater is unpredictable, so the well head which was first installed here turned out to be inadequate and had to be changed. The Mexican riggers let me know we were about to get a rare chance to see a real gusher.