Features Reporter
“Geology does not do well on its own,” said Dr. Rex Cole, professor of geology at CMU, to open his lecture about the formation of gas wells. However, understanding how the earth came to be and how long it took is the major factor in determining where gas wells are placed.
Cole spoke about the stratigraphic formation of oil and natural gas. His research involved the Piceance Basin of the Colorado Plateau.
“It’s like we’re building a car,” Cole said. “It has to have an engine, it has to have tires, it has to have a braking system. That’s why it’s called a system. These components have to be together.”
The formation of oil and gas all depends on the geology of the surroundings.
“If the appropriate geology is not there, the resources are not there,” Cole said.
In geological terms, there are five specific elements that are necessary for the natural synthesis to occur, along with dramatic temperature increases further underground.
“Like baking cookies, it has to be at the right temperature for the right time,” Cole said.
The first element necessary is source rock, usually shale, as the producer of the oil and gas. On top of the source rock, reservoir rock is the porous rock that is drilled into. Seal rock is the surrounding rock that “plugs” the porous openings so that water, gas and oil do not migrate to the top. They have the tendency to migrate upward due to extreme pressure oil’s property of staying above water. Overburden rock is essential to keep the fractures formed in the reservoir rock closed. Geological timing is vital.
“If events don’t occur in order, then game over,” Cole said. These five elements take millions of billions of years to produce. The most challenging part to Cole is “trying to get people used to thinking about millions and billions of years.”
Alone, however, these geologic features are not what create oil, they just provide the setting and trap. Organic material is needed. Over time, mud sinks and is eventually covered by reservoir rock. This mud heats up as it descends. Heat “cooks” the mud, which is full of organic material like algae and bacteria.
“It’s kind of a misconception that all oil comes from dinosaur belly button lint or something,” Cole said.
Trapped by the seal rock, the oil and natural gas can be extracted. Locally, this is done in the Piceance Basin. The prominent source rock is Green River oil shale. According to Cole, this oil shale is a “world- class source rock,” because 30 percent of it is organic material.
Alexandra Price, a CMU senior studying geology, said the most important takeaway from the lecture was “the stratigraphic limits and resources in each one.” As Secretary of the Earth Honor Society, Sigma Gamma Epsilon, Price is extremely interested in how landscapes form, especially the Colorado Plateau.
caoconno@mavs.cooradomesa.edu
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