DALLAS -- Saturday's Oklahoma earthquake that shook people from Texas to North Dakota put a new dent in the idea that fracking-linked temblors were too small to matter. Oklahoma and federal officials quickly ordered the closing of water disposal wells that may have caused the largest quake ever measured in the state.
Now, industry experts are left with the task of finding new ways to process that wastewater.
Experts say there are some answers. Some are already being tried. Some could be expensive. But either the water gets managed, or there's the risk of shutting down thousands of oil and gas wells in Oklahoma and in other states, including Texas, where scientists have drawn links to earthquakes.
"The answers are not easy, by any means. There is a whole lot of economy at stake," said John Veil, a consultant who started studying the connections between water and oil and gas production when he worked for the Argonne National Laboratory.
Saturday's 5.8 magnitude quake was the biggest ever measured in Oklahoma and was felt in neighboring states. Pawnee was most affected, but other towns reported damage ranging from cracks in walls and foundations to food on grocery shelves tossed to the floor. Two smaller quakes were reported Tuesday.
The state ordered 37 water wells to be closed. Federal authorities expanded the closure to 17 wells on American Indian land nearby that the state has no authority over.
"This was an emergency response," said Matt Skinner, spokesman for the Oklahoma Corporation Commission. "We don't consider this a final step."
The commission oversees much of the state's regulation of the oil and gas industry. Earlier this year, it had called for a phased reduction of the amount of water that can be injected in wells considered most significant in increasing the risk of quakes.
Oklahoma has experienced a sharper rise than Texas in the number and strength of earthquakes. But both states have experienced significant increases over the past decade, as the number of oil and gas wells has increased.
The chain that many scientists say connects petro-production to earthquakes has several links.
Geologists say the shaking is not connected directly to the oil production process called hydraulic fracking. Wells using that system push treated high-pressure water and sand underground to blow cracks into rocks where oil and gas are trapped. Some of that water comes back up the well as "flowback." But much, much more water that had been trapped with the oil and gas also comes to the surface.
Geologists estimate that as much as 10 times more water-based fluid comes out of U.S. wells during their lifetimes as oil. And while conventional wells have produced water for years, the boom in fracking has vastly increased the number of active wells in the U.S.
"If it weren't for fracking, we would not be here talking about these earthquakes," said Johnson Bridgwater, head of the Oklahoma Sierra Club. Earlier this year, the club filed a federal lawsuit against three oil and gas production companies because of the Oklahoma earthquakes.
Veil did a study of what is called "produced water" from 2012. He estimates that about 20.3 billion barrels of water came out of onshore wells that year. Much of the waste is a greasy brine carrying the salt of ancient oceans plus toxic minerals dissolved over millions of years. So it can't simply be dumped into a lake or river.
Nationally, about 46 percent of that water got recycled directly in the oil fields. A lot of it is used to increase the pressure near conventional wells, which increases the oil and gas flow. Some of it can be processed and used to frack another well. Neither of those have been tied to earthquakes in Texas or Oklahoma.
Some states reuse much more than others. Ohio, for instance, is recycling almost all of its oilfield water, said Brian Schwanitz, a consultant with Welltec, an oilfield service company.
But about 47 percent gets injected into wells that are much deeper than the oil formations and underground drinking water reservoirs.
Deep injections had been considered a safe way to get rid of the water. But as fracking vastly increased the number of wells drilled in Texas and Oklahoma, producing more water needing disposal, seismologists noticed a rise in the number of earthquakes. Scientific studies indicate that the deep injection wells can put pressure on faults underground. When the faults slip, that creates earthquakes.
While Texas officials continue to deny the connection, Oklahoma has supported the scientific consensus for several years.
"It's not coincidental that the data indicates the earthquakes have increased along with the number of wells," Skinner said.
Several companies across the country have developed options for disposing wastewater beyond injection. Clane LaCrosse, head of Fort Worth-based Bosque Systems, said his company has solutions.
His company processes about 30 million barrels of fluid a month in oil fields across the U.S. All of it goes back into the ground for newly fracked wells. And as long drilling stays active in the fields, he said, a lot of the produced water can be reused.
"In the Permian Basin, you can reuse 100 percent of the water," he said.
The drop in crude oil prices has slowed drilling. But today's fracking uses a lot more water than similar wells from a few years ago. And that means it takes far fewer rigs in the field to generate need for water, LaCrosse said.
Paradoxically, the increase in fracking may eventually reduce the amount of water that needs to be managed, Veil said. From 2007 until 2012, fracking increased oil and gas production in the U.S. by more than 20 percent. The volume of produced water barely budged, Veil said.
Conventional wells produce more and more water over time, he said. Fracked wells have an initial quick flowback. But the ratio of water to gas and oil actually drops as the well ages.
While the technology to reuse water has gotten better, the incentive to use the systems hasn't, Schwanitz said. Without pressure from new regulations, that's not likely to change, he said. But low oil prices may actually nudge some operators into considering recycling if the cost of reusing water goes down.
"When the price was high, they were drilling so many wells so fast, it was all about getting the well down and getting the production. Now they need to do real reservoir engineering," he said. "There's a business opportunity there."
Business on 09/09/2016
Print Headline: 5.8 temblor renews search for ways to dispose of oil-, gas-well wastewater