Lessons learned more than a century ago from the 1906 San Francisco earthquake are helping a team of researchers at Oklahoma State University make oil and natural gas drilling in Oklahoma more efficient.
Priyank Jaiswal, assistant professor of seismology at Oklahoma State University’s Boone Pickens School of Geology, and his research team are studying hydraulic fracturing, or fracking, by using high pressure water and other fluids to shatter simulated rocks made of concrete and other materials.
Lessons learned more than a century ago from the 1906 San Francisco earthquake are helping a team of researchers at Oklahoma State University make oil and natural gas drilling in Oklahoma more efficient.
Earthquake research has shown that seismic activity temporarily turns the consistency of rocks around a fault into something like plastic, reducing the ability to experience additional seismic activity for some time. After the San Francisco earthquake, the affected rock did not experience another earthquake for three decades.
OSU researchers have found that hydraulic fracturing, or fracking, can cause a similar effect, though on a much smaller scale.
When companies shatter rock deep below ground to boost oil production, the nearby rock can become resistant to fracking for some time. In some cases, the plastic-like rock can open just enough to let water through to the well bore, but not enough for larger oil molecules, said Priyank Jaiswal, assistant professor of seismology at OSU’s Boone Pickens School of Geology.
Jaiswal and his research team hope to help companies produce more oil and less water from their drilling and production operations.
“The most important thing we’ve learned so far is that fractured spacing cannot be uniform, as is the normal practice of industry,” Jaiswal said. “It may be that the first and second fracture need only be spaced 30 feet apart and the next two might need 90 feet. But it is definitely not uniform.”
Evolving technology
While oil and natural gas companies have used hydraulic fracturing in varying applications for more than half a century, the process combined with horizontal drilling has become the dominant drilling technique throughout the country only over the past decade.
Fracking is completed by pumping large amounts of mostly water and sand at high pressure into shale or other dense rock. Companies continue to experiment with how many fractures to make on each well and how closely those fractures should be placed.
If the fractures are too close together, Jaiswal said, they could counteract each other and reduce the efficiency. Spaced too far apart, companies could miss out on nearby oil and natural gas that never makes it to the surface.
“Our frack spacing is not optimized,” Jaiswal said. “We should optimize it based on the expected composition of the rock and the expected fabric of the rock.”
A second look
Jaiswal also is looking at the effort to refrack a well. With traditional vertical wells, companies recomplete wells from time to time by redrilling the hole or adding pumps and other mechanisms. The modern use of hydraulic fracturing is new enough that there is no consensus about whether refracking a well would be useful.
Jaiswal’s research indicates it depends on whether the rock around the first set of frackings has turned to a plastic-like consistency and whether it has become brittle again.
“The technology of hydraulic fracturing is amazing, but there is still a whole lot to learn about whether we are wasting our resources or utilizing them in the best possible way,” Jaiswal said.
The first phase of the research was funded with a grant from the Oklahoma Center for the Advancement of Science and Technology. Jaiswal is applying for funding for the second phase of his research and is hoping to partner with an oil company for the work.
Student researchers
Jaiswal’s team is made up of three undergraduates and one graduate student. The students are mechanical engineers and material scientists — not geologists — because the researchers are not studying rock as much as they are how fluids move through and around the rock.
“Before I started this project, I didn’t know how fracking was done,” said Josh Musto, a mechanical engineering senior. “We learned about utilizing pressure vessels and pressure specimens and the material science behind concrete and other samples. It was a design process for us as undergrads: How are we going to fracture the concrete in the simplest, most effective and safest manner?”
Besides working to improve one of the largest industries in Oklahoma, the research team members said they also hope for other, more immediate benefits.
“It’s all over my resume,” Musto said of the project. “It definitely seems applicable to the things I could be doing in my career. I don’t see how it wouldn’t help me going forward.”
Source:
Adam Wilmoth
The Daily Oklahoman
http://newsok.com/osu-researchers-hope-to-improve-oil-production-by-better-understanding-rocks-and-engineering/article/5371441
