by Celia Llopis-Jepsen, Kansas News Service
Saltwater injection. Fracking. Enhanced oil recovery.
News of protests in recent months against oil- and gas-related activity in the Flint Hills has drawn fresh attention to these and other terms — as well as some confusion.
A saltwater injection well that made headlines in recent months in Morris County, for example, was not an example of fracking — though nearly 4,000 people joined an online petition describing it as fracking. The online petition was then submitted to Kansas energy regulators last month. The same term — fracking — also appeared in a few news headlines describing that well.
So what is saltwater injection and what is fracking?
Below is a primer based on conversations with and materials from experts at the U.S. Geological Survey, Kansas Geological Survey at the University of Kansas, Stanford University and Kansas Corporation Commission, the state’s energy-regulating body.
What are saltwater injection wells?
These are wells where oil and gas companies dump wastewater for one of two purposes — either simply to get rid of it (“disposal”) or to help get more oil and gas out of the ground (“enhanced recovery”).
Disposal wells: When energy companies produce oil and gas, they churn up wastewater in the process that is primarily saltwater (more on this topic below). It needs to go somewhere. Frequently the companies put it even deeper into the ground than where they found it. These disposal wells are often near the oil or gas production wells that are churning out the wastewater. The fluid can be trucked or piped to the disposal wells. According to state energy regulators, Kansas has around 5,000 of these wells.
Enhanced oil recovery: This process is another common fate for that unwanted saltwater. The goal is to extract hard-to-reach oil (or, less commonly, natural gas) — for example, from an already somewhat depleted field. To that end, producers pump wastewater into the oil field to flush the oil there toward other wells where it can be extracted. Kansas has more than 11,000 wells where saltwater is injected for this purpose.
Though both saltwater disposal and enhanced oil recovery have been known to cause earthquakes, disposal is more likely than enhanced recovery to cause them.
Why are there so many earthquakes in south-central Kansas and Oklahoma?
Since 2008, thousands of temblors strong enough for people to feel have struck parts of Oklahoma and Kansas. The number of quakes in south-central Kansas picked up in 2013.
The most recent USGS annual report on the matter concluded that parts of these two states now face seismicity risks similar to those in earthquake-prone California.
Though an oil and gas industry practice called fracking has been shown in some cases to cause earthquakes that are strong enough for people to feel, geophysicists say the main culprit causing the temblors in Oklahoma and central Kansas is saltwater disposal, not fracking.
In Kansas, state energy regulators have since 2015 reduced saltwater injection rates for wells in parts of south-central Kansas. The number of earthquakes fell sharply.
Can we predict whether a new saltwater injection operation will cause earthquakes?
Geophysicists contacted for this article say the answer is “no” — scientists can’t predict with certainty. But they have identified statistical trends that give clues regarding the likelihood of quakes. For example, disposal wells that take in high volumes of wastewater are more likely to cause earthquakes than their lower-volume counterparts.
What exactly is a high volume? This University of Colorado research points to wells that take in more than 300,000 barrels of fluid a month, while this University of Texas study looked at wells receiving 150,000 barrels a month. Each barrel holds 42 gallons.
High volumes alone do not fully explain quakes. Other factors come into play, such as the proximity of wastewater wells to fault lines. Across the United States, most wastewater wells — disposal and enhanced recovery wells alike — have not been linked to seismic activity.
What is fracking?
Companies can use hydraulic fracturing — better known as fracking — to boost oil or gas output. It usually works like this: A company builds a well and, before starting production, injects fracking fluid at a high pressure to create cracks in the rock. Then production starts and those cracks help extract the oil or gas.
It’s a treatment that can take hours or days to complete. It’s not a continual, ongoing process, like saltwater injection, which doesn’t normally involve fracking. According to an article in Seismological Research Letters, a publication of the Seismological Society of America, companies apply the fracking treatment to tens of thousands of wells nationwide each year.
The KCC doesn’t have an online database of fracking activity in Kansas, but its website links to FracFocus, which does although the information is incomplete. That’s because energy companies can report large-volume fracking treatments to FracFocus to meet KCC reporting requirements, but they aren’t required to pick that option.
What’s in the wastewater known as “saltwater”? And what’s in fracking fluid?
This varies a lot, scientists say. In some states, the wastewater is largely fracking fluid. In Oklahoma and Kansas it is mostly brine that is trapped deep in the ground and gets pulled up with oil and gas.
When companies pump this brine back into the ground for disposal or enhanced oil recovery, it can contain chemicals — including those found in fracking fluid — and residual oil and natural gas.
The KCC describes these non-brine substances as “generally found in no more than trace quantities.”
The Kansas Geological Survey, which studies the chemical makeup of oil wastewater from sites across the state, also says it is primarily brine and that it is exceptionally heavy — sometimes many times saltier than ocean saltwater.
As for fracking fluid, the KGS says it is a mix of water and other ingredients — such as sand to prop open the cracks that are created and biocides and anti-oxidation chemicals to prevent bacteria and rust.
What about contamination risks?
In 2012, a multistate investigation by the online news outlet ProPublica into wastewater wells found the fluids being injected into them can contain a variety of hazardous substances that face more stringent regulations for handling and disposal when they occur in other industries.
The investigation suggested lack of government oversight and instances of unscrupulous dumping and contamination of groundwater raise questions about the safety of saltwater wells.
The KCC, however, says the wastewater is poured into layers of rock where it won’t endanger usable groundwater. It also says the wells are designed with three layers of casing to shield against contamination.
In the first half of the last century, contamination of freshwater by oil wastewater was a significant problem in Kansas, leading the state to legislate underground disposal procedures and ban above-ground dumping pits.
The KCC documents contaminated and risky sites that are being cleaned up or monitored by the state in an annual report that it publishes online. The report includes information on topics beyond saltwater injection.
KGS senior scientist emeritus Don Whittemore, who has studied groundwater contamination by salt and saltwater since the 1970s, reviewed the 140-page 2017 report for the Kansas News Service and said some current contamination stems from poor practices decades ago.
“As far as I can see, the injection wells that are related to contamination were older wells that were probably not constructed as well as those wells would be today, and which probably did not undergo the periodic mechanical integrity tests conducted today. … It is not apparent to me that any recent injection wells have been identified as the source of contamination.”
The report also documents a few sinkholes linked to saltwater wells that caused groundwater contamination or have created a risk of contamination. It also lists a few sites related to saltwater line leaks and to the now long-banned aboveground dumping pits. Or, in some cases, the source is unknown. (In Kansas, salt can enter groundwater from a variety of industry and natural sources, not just saltwater wells, Whittemore said.)
Whittemore also said some instances of contamination have occurred in southeast Kansas when fluid bubbled up through older abandoned saltwater wells that were never plugged at all or at least not thoroughly enough. The abandoned wells since have been plugged to stop further contamination.
In terms of fracking fluid specifically, the KGS website says cases of groundwater contamination haven’t been documented in Kansas, despite recorded instances in other states.
Celia Llopis-Jepsen is a reporter for the Kansas News Service, a collaboration of KCUR, Kansas Public Radio, KMUW and High Plains Public Radio covering health, education and politics. You can reach her on Twitter @Celia_LJ. Kansas News Service stories and photos may be republished at no cost with proper attribution and a link back to kcur.org.