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Environmental Impacts

Hydraulic Fracturing: Impacts from Produced Water

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Today is my final post covering the U.S. Environmental Protection Agency’s (EPA) December 16, 2016 report: “Hydraulic Fracturing for Oil and Gas: Impacts from the Hydraulic Fracturing Water Cycle on Drinking Water Resources in the U.S.”  I reviewed EPA’s analysis of the potential for drinking water contamination during the oil and gas industry’s management of produced water. EPA includes within the definition of produced water both the fluid which has been injected down a well to hydraulically fracture oil and gas rock formations and the normally salty water contained within the rock formation itself. Once rocks are fractured and the pressure is released on a well undergoing hydraulic fracturing, part of the hydraulic fracturing fluid and some of the salty formation water flow back up the well to the surface. The management of the produced water once it reaches the surface is important to safeguarding drinking water resources.

 

Spills are probably the number one problem with waste handling in most industries, so it is not surprising that there are multiple ways produced water is spilled at oil and gas wells being drilled or hydraulically fractured. We are all too familiar with the blowout and spill which occurred in the Gulf of Mexico in 2010. Who did not see the underwater videos of oil and brine pouring out of the well on the sea floor? After all it went on for 5 months. Blowouts occur on-shore as well. When they occur at a well being fractured, it can result in oil and gas, formation water, and hydraulic fracturing fluid all coming back up the well and being released at the ground surface. If the well casing is damaged during the blowout then there is also the potential of produced water being released into rock formations with groundwater aquifers. Fortunately blowouts are very rare. When blowouts occur on-shore, it is easier to stop the flow and to clean-up the mess. Just as problematic, though not as spectacular, are the spills of produced water from day to day management activities.

 

When oil and gas wells are new, they produce more water. Horizontal wells produce more water than vertical wells. More hydraulic fracturing chemicals will be in the produced water during the early life of a well. Over time the produced water will be composed predominantly of the salty formation water from the oil and gas formation. Unfortunately the formation water is not benign. It is brine and full of chlorine, bromine, metals, organic oil and gas constituents, and naturally occurring radioactive minerals. There is a lot of this produced water coming up from active oil and gas wells all over the United States, whether they have been hydraulically fractured or not. EPA estimates horizontal wells produce 1100 gallons of produced water per day and vertical wells about 500 gallons a day. But the exact volume depends on the actual formation being fractured. The rock formation also determines what the composition of the produced water will be. For example in the Marcellus Shale, the produced water contains more barium and strontium. But even within a single rock formation like the Marcellus, the composition can vary widely. EPA has documented salinities of between 1500 and 300,000 milligrams per liter in the Marcellus Shale. The produced water characteristics of hydraulically fractured wells are not substantially different from produced waters out of wells which have not been hydraulically fractured. The main difference between the two types of water would be the chemicals used in hydraulic fracturing; chemicals like ethylene glycol, propylene glycols, toluene, xylene, 2-butanone, acetone and many others. Chemical additives are a small amount of the total fluid used for hydraulic fracturing, on average less than 1 percent. Most of the fluid used to fracture a well is simply water.

 

When the produced water reaches the surface, it must be managed. Either it is collected in tanks or discharged into pits. Thank goodness state governments have ended the practice of allowing discharge into unlined pits. According to EPA, unlined pits have been the source of contamination to water in a number of cases in New Mexico, southwest Pennsylvania and possibly in Texas. But lined pits can leak too if the liner isn’t installed adequately. Produced water is often piped to pits or storage. There have been a number of incidents where pipelines have broken or valves have been accidentally left open. In 2015, North Dakota had one of the largest pipeline spills of produced water. About 2.9 million gallons of produced water were released.

 

Of course pipelines sometimes leak. So does other equipment the produced water passes through, such as hoses. Even storage containers leak. The best data that EPA was able to come up with in examining the various sources of spills was from North Dakota. There were 552 leaks or spills between 2012 and 2013.  EPA says that was somewhere between 5 – 7 releases of produced water per 100 active production wells. Most of the produced water spills were the result of equipment leaks and overflows of tanks. This seems like a lot of spills to me. Of course not every spill was a big one; they ranged from 170 gallons to 74,000 gallons.

 

Pits and storage containers are not the final resting place for produced water. With the amount of water being produced over the lifetime of an oil and gas well, the water has to be permanently disposed of somewhere. Most states have lots of disposal injection wells permitted under the Underground Injection Control regulations. So in the majority of oil and gas producing states, the produced water is piped or trucked to an injection well for disposal. Injection wells are installed into permeable rock formations at great depths and are specifically designed for final disposal of liquid waste. EPA says in 2012, there were 26,400 disposal injection wells and 65 % of them were located in Texas, Oklahoma and Kansas. EPA cites a study that estimates 93 % of all produced water in the U.S. is injected into disposal wells.

 

Interestingly enough Pennsylvania only has 9 permitted underground injection wells in the whole state. Trucking produced water to another state where there is a disposal well is pretty expensive, except in southwest Pennsylvania. At one time produced water in Pennsylvania was being sent to Publically Owned Treatment Works (POTWs). These facilities treat municipal waste. Produced water was also being shipped to commercial facilities called Centralized Waste Treatment (CWT). This is no longer allowed in Pennsylvania because neither POTWs nor CWTs were able to treat the produced water from the Marcellus adequately and it was causing problems for downstream drinking water suppliers. Today over 80 % of produced water in Pennsylvania is being treated and reused as water to hydraulically fracture oil and gas wells.

 

In the 10 years it has taken EPA to write their report on the impact of hydraulic fracturing on drinking water resources, a lot of improvements have been made in management of produced water which consequently has reduced potential impact on drinking water. It looks like more improvements could certainly be made in produced water management. Many of the produced water spills are caused by human error or equipment failure. EPA was unable to quantify the number of spills of produced water nationally or the affects on drinking water sources. However, they did examine a few states which keep spill records. EPA found that of 575 produced water spills in California between 2009 and 2014, 18 percent impacted surface water. Quality improvement in produced water handling could reduce the number of spills and impacts on drinking water resources.

Environmental Impacts

Hydraulic Fracturing: Movement of Gas and Fluid in the Subsurface

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Today’s post looks at ways injected hydraulic fracturing fluid might move through the subsurface and contaminate groundwater. The information in this post is based on the U.S. Environmental Protection Agency’s (EPA) December 16, 2016 report: “Hydraulic Fracturing for Oil and Gas: Impacts from the Hydraulic Fracturing Water Cycle on Drinking Water Resources in the U.S.”

 

Wells are constructed to withstand the pressures applied during injection of hydraulic fracturing fluid. The fluid is mostly water and sand with on average about 1 % chemical additives. Wells are constructed by inserting steel casing down a borehole and cementing it next to the rock formation. The cement prevents fluid and gas from coming back up along the sides of the casing. State regulators generally require protection of groundwater resources and so casings are cemented (at a minimum) from the surface to below the groundwater zones. The goal of hydraulic fracturing is to inject solution down the hole under enough pressure to produce long horizontal and vertical fractures in the oil and gas formation. The sand in the solution then props the fractures open, so the gas and oil can flow out of the rock and up the interior of the casing to the surface. Once the pressure on the well is released, most of the hydraulic fracturing fluid comes back up the well and is captured in tanks for disposal. It is the fate of the fraction of fluid lost in the fractures which is a concern in EPA’s study. There are fluids and minerals already existing in the oil and gas formation. Some of these fluids and minerals come back up the well with the hydraulic fracturing fluid. EPA’s report examines whether these naturally occurring fluids and minerals can be activated by the hydraulic fracturing process and move through the subsurface. EPA is also concerned with whether the hydraulic fracturing process might cause gas in the targeted oil and gas formation or in the overlying rocks to move through the subsurface into groundwater.

 

Unfortunately the EPA has only been able to identify a limited amount of research on fluid and gas movement once an oil or gas well has been hydraulically fractured.

As a result there are a lot of limitations on EPA’s ability to provide any definitive conclusions on fate and transport of gas, hydraulic fracturing fluid, or naturally occurring groundwater and minerals through the subsurface. EPA examines two pathways fluids and gas might move into groundwater during and after hydraulic fracturing. The first pathway is a result of the age old method of human frailty, in other words, a bad well design or poor construction of the well. Also included in this pathway is the lack of permanence of human construction or your basic entropy – the eventual degradation of the steel casing or cement. The second pathway EPA examined is the movement of gas and fluid through the fractures created by hydraulic fracturing into naturally existing fractures, faults, and nearby operating or abandoned oil and gas wells, or in other words, unintended consequences.

 

What kind of scientific or technical evidence did EPA find to support the existence of these two pathways? First there’s the technical data EPA collected from the oil and gas industry, although it is incomplete. There is the research by non-EPA scientists who have examined data collected from the oil industry or who have produced independent data themselves, and then there is groundwater modeling. As someone who has conducted and used groundwater models, I always caution on the usefulness of this methodology. There are so many variables in the subsurface; it is often hard to use models as more than just a tool to assess the many probabilities which might occur. But in this case, groundwater modeling has provided some interesting and pretty definitive insights into what can happen to fluids and stray gas during and after hydraulic fracturing.

 

So did research show there are subsurface pathways through which groundwater contamination can occur during and after hydraulic fracturing takes place? EPA reviewed data collected from the oil and gas industry and found that in roughly 3 % of wells hydraulically fractured, there was a mechanical failure of the well. This means some fluid or gas may have escaped along the outside of the casing during the hydraulic fracturing process. Where it went is a guess. Just because the casing or cement failed, it doesn’t mean fluid or gas moved into groundwater. Only in about 0.5 % of these cases did the well not have cement or some other type of barrier protecting the groundwater. Of course there are some notable well failures which have contaminated groundwater, like the ruptured casing resulting in a large surface spill in Killdeer, North Dakota during 2010. Based on groundwater chemistry, scientists think there are also some hydraulically fractured gas wells in the Marcellus Shale in Pennsylvania which have contaminated drinking water resources with natural gas as a result of poorly cemented casing. And there’s another incident in Ohio where gas moving up the exterior of casing into groundwater was thought to have been caused by poor cementing. A number of oil and gas wells being hydraulically fractured are not new wells. Of the oil and gas wells EPA examined about 19 % were older wells. They ranged in age from 8 days to 51 years. EPA noted there were more casing and cement failures in these older wells. So yes there is a limited amount of data showing oil and gas wells being hydraulically fractured can fail and be a pathway for groundwater contamination.

 

What about movement of fluid and gas through new and existing fractures? What technical evidence did EPA find to determine if this was a clear pathway for contamination? Studies have shown that hydraulic fracturing results in vertical fractures in rocks at depths greater than 2000 feet and horizontal fractures in rocks shallower than 2000 feet. EPA was interested to know if fractures can extend out of the rock formation being fractured and into overlying rocks containing groundwater. EPA cites studies showing vertical fractures from hydraulic fracturing operations can extend several thousand feet upward, however fracture length is really dependent on the rock formation being fractured. For example in the Marcellus Shale, most vertical fractures only extend for a few hundred feet. EPA argues the depth of most oil and gas rock formations and their great distances from overlying aquifers prevents movement of fluids and gas along induced fractures into drinking water. Based on the data reviewed by EPA, only 20 % of wells had less than 2000 feet between the shallowest point where fractures could extend upward and the base of the drinking water formation.  This doesn’t mean fractures are not a pathway through which groundwater could be contaminated. It just means it is highly unlikely in most cases. EPA has more concern about this potential pathway for contamination when hydraulic fracturing is either in the same formation as a drinking water resource or a drinking water resource is less than 200 vertical feet from the oil and gas formation, as occurs in several places in Wyoming and California.

 

EPA examined several studies assessing the likelihood of what happens to hydraulic fracturing fluid which does not come back up a well once a well is depressurized. These fluids are called “leak off” and most studies show they are absorbed onto clays or are inhibited from moving out of the local area of the well by various physical forces in the subsurface. You’ve got to remember, the rocks being fractured lack permeability (the ability of liquid and gas to move through them.) It’s why the rocks are being fractured in the first place. But then again, some studies have shown the “leak off” fluid can displace gases in the pore space, which means until the oil and gas well starts operating and sucking up all the oil and gas in the area there is a period when you might have some movement of the gas into and along the fractures. Most modeling studies show the gas shouldn’t reach overlying drinking water resources without a direct conduit upward like a fault or an abandoned well. And then there are a few conflicting studies, where natural gas from underlying oil and gas formations has been found in shallow aquifers and EPA has been unable to identify a clear subsurface conduit.

 

So has EPA proved the potential of poorly constructed and damaged wells to transmit gas and fluid to drinking water resources – yes and no. They have certainly shown a few documented cases where contamination has occurred as a result of poor well construction and well failure. EPA has not however provided a good thesis for how frequently contamination along this pathway occurs. Not their fault – there is simply not a lot of available data which EPA could rely on to make such a determination. How about the potential pathway along natural fractures, faults, and abandoned wells? Has EPA proven or disproven the existence of such routes for fluid and gas movement and the degree of impacts groundwater is suffering as a result? Again yes and no – EPA has cited a couple of studies which have shown direct movement of gas up uncemented casing into natural fractures and other subsurface features then into ground and surface water. But then the modeling of such scenarios presented in the EPA report pretty clearly shows that once production starts all gas and liquids should flow into the production well and not be migrating elsewhere.

 

EPA states “The limited amount of available information hinders our ability to evaluate how frequently drinking water impacts are occurring, the probability that these impacts occur, or to what extent they are tied to specific well construction, operation and maintenance practices. This significantly limits our ability to evaluate the aggregate potential for hydraulic fracturing operations to affect drinking water resources or to identify the potential cause of drinking water contamination in areas where hydraulic fracturing occurs.”

Environmental Impacts

Hydraulic Fracturing Impacts on Drinking Water – Chemical Spills

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I have been writing a series of posts over the last month on the final report from the U.S. Environmental Protection Agency (EPA) covering the environmental impacts of hydraulic fracturing of oil and gas wells on drinking water resources. The report is entitled:  “Hydraulic Fracturing for Oil and Gas: Impacts from the Hydraulic Fracturing Water Cycle on Drinking Water Resources in the United States” (EPA-600-R-16-236Fa, December 13, 2016.) Today’s post concerns the potential impacts of chemical spills during the hydraulic fracturing process. This is my fourth post on the report overall and I will admit up front, it’s the worst post I have ever written. Not my fault. Unfortunately, there is just a total lack of quality data in the part of EPA’s report which covers chemical spills at oil and gas well sites being hydraulic fractured.

 

Hydraulic fracturing is not the only industry where mixing and transferring chemicals and fluids create spills. Spills happen in all sorts of industries and with all sorts of transportation. If you have worked in the environmental field for a while then you know chemical spills are still a problem throughout the United States, even though regulators and companies alike have worked aggressively to prevent them over the last forty odd years. I thought hazardous materials spill responders would all be out of a job by now. Hah, not so. The reason they’re not all collecting unemployment is mostly due to the human element involved in the process of mixing or transferring chemicals – in other words you and I screwing things up.

 

For their report, the EPA has sought to quantify the number and type of chemicals spilled at well sites which have undergone hydraulic fracturing and to determine the causes of the spills. EPA used data gathered by state governments and industry over a period of six years starting in 2006. EPA sorted through all this data and drew some conclusions.

 

For example, EPA learned through their data analysis that the combination of chemicals used in hydraulic fracturing is based on local conditions. Local conditions are such things as the type of rock formation being fractured and the type and quantity of fluid with which the chemicals are mixed.  The variability of chemical mixtures from site to site results in there being very little in common nationally in the types of chemicals spilled at oil and gas well sites. The chemical formulation of a fracking fluid in Pennsylvania can be completely different from the fracking fluid formula in West Texas or North Dakota.

 

The state and industry data also showed human error as the cause of the greatest number of spills at well sites, followed closely by equipment failure (such as hoses transporting chemicals) and failure of  containers storing chemicals. Out of approximately 36,000 spills reported in the state and industry data, EPA identified only 457 that were at or near the actual well site being fractured. Of these 457 spills, 151 were a result of chemical mixing operations at the well site. Of the 151 spills, 54 came from storage containers. Sixteen of the spills were actually caused by holes and cracks in the containers. In fact, storage containers were the number one source of spills which reached a drinking water resource. Storage container failures resulted in the most concentrated chemical spills and the largest volume of chemicals spilled, because the chemicals are generally being stored in a concentrated form. Once the chemicals leave storage and are mixed in tanks with fluids (generally water) for use in hydraulic fracturing then they become diluted and the impact of a spill is not as severe. One of the problems with the state and industry data collected by EPA is that there’s little actual information on the exact chemicals spilled at the well sites. There are just general descriptions, such as: oops we spilled some acid or a biocide. There’s better information on the volume of the spills though. The amount of chemicals spilled as a result of the mixing process ranged from 5 to 19,000 gallons.

 

Of the 457 spills which occurred at an actual well site, 225 were of produced water. Produced water consists of the natural groundwater in the oil and gas formation plus the remnants of the hydraulic fracturing fluid. Once hydraulic fracturing has taken place and pressure is released at the wellhead on the surface, then produced water comes back up the well bore. Usually it is collected in tanks, but obviously there have been spills. Produced water contains only very dilute amounts of the hydraulic fracturing fluid chemicals.

 

I know what you are thinking. You saw the big number of 36,000 spills. What the heck are all those spills? Sorry it is a bit of a mystery, because the data used by EPA is so bad. Other than the 457 spills mentioned above, EPA couldn’t determine where approximately 12,000 of the spills occurred. On top of that, 24,000 of the spills weren’t at the oil and gas well sites at all.

 

Did any of the identified 457 spills at the well sites cause contamination? You bet, 101 of the spills contaminated something, mostly soil (97 of the spills). Thirteen spills reached surface water and 9 of the spills contaminated both soil and surface water. There was no reporting on whether groundwater was contaminated because nobody is monitoring groundwater at hydraulic fracturing well sites.

 

What does this all mean? I don’t know. It’s the reason I called this post the worst I’ve ever written. The weak data on which the report is based makes it hard to say anything about the state of drinking water contamination caused by surface chemical spills at hydraulic fracturing well sites. Obviously there is a big gap in EPA’s analysis. But you know, it is hard to effectively quantify spills from incomplete and inconsistent data.

 

Probably the most interesting part of EPA’s report on chemical spills at hydraulic fracturing well sites is their analysis of the potential for chemicals used in hydraulic fracturing to migrate into water. Not all chemicals are equal in their ability to move through soils or water. EPA uses a set of chemical properties (for example the ability of the chemical to volatilize into the air and the ability of a chemical to dissolve in water) to determine if the chemical is one that is going to immediately contaminate a drinking water resource or if the chemical is going to hang around all gummed up in the soil and be a source of long term contamination as it slowly leaches drop by drop into groundwater and surface water. Of course nowadays, most spills that contaminate soils get cleaned up right away, so the second scenario involving long term contamination is unlikely in most cases.

 

Here’s what I thought was interesting about the chemical migration analysis. EPA states that of the 20 most frequently used chemicals in hydraulic fracturing nationwide, the majority are soluble (meaning they readily dissolve in water). The most soluble and mobile in water are methanol, isopropanol and ethylene glycol. There are a few petroleum based organic chemicals in the top 20 most frequently used chemicals in hydraulic fracturing that are not very soluble. But as EPA points out, there are other chemicals used in hydraulic fracturing fluid, like surfactants or alcohols, which can enhance the mobility of organic chemicals including those that are petroleum based. In other words, alcohol carries the organic chemicals along with it in the water. Fortunately chemicals in the environment are not necessarily forever. They are subject to breakdown by bacteria or by chemical transformation. So a chemical like methanol will eventually break down over a period of time to formaldehyde then to formic acid and finally to carbon dioxide.

 

Anyway, I’m going to say here, EPA’s report is less than a stellar account of the rate and fate of chemical spills at hydraulic fracturing sites. I suppose if you have bad data, you just have to kind of make do with what you have and at least try to say something about it. After all EPA has taken six years to produce a report to Congress. I guess they didn’t want to have to write in the report that their method of analyzing the scope and impact of chemical spills was a total bust. And I suppose regulators and industry can use the information, no matter how small a data set it is, to direct their attention to prevention efforts. Since most of the spills are from containers, they could concentrate attention on conducting inspections of storage areas. But does the report give a national picture of whether chemicals spilled during the hydraulic fracturing process are affecting drinking water resources? No, I don’t think so.

Environmental Impacts

Update on EPA’s Science Advisory Board Peer Review of the Draft Report on Impacts of Hydraulic Fracturing on Drinking Water

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As regular readers of the Waterblogger know, the Environmental Protection Agency’s (EPA) Science Advisory Board (SAB) is busy finalizing its peer review of the agency’s draft report: “Assessment of the Potential Impacts of Hydraulic Fracturing for Oil and Gas on Drinking Water Resources.”  If you haven’t been reading Waterblogger regularly the original article is below.

Science Advisory Board Peer Review of the EPA’s Draft Report on Impacts of Hydraulic Fracturing on Drinking Water

I’ve been following the SAB’s discussions through the public teleconferences. The first was on February 1, 2016. Consequently a second draft of their 133 page peer review report was issued on February 16, 2016. A second conference call was held on March 7, 2016. These are long conference calls. The March 7 conference call went some seven hours. The first two hours were dedicated to registered speakers. Anybody can be a registered speaker. All you have to do is apply. You get three minutes. Very little scientific work is presented by these speakers. Most speakers are representatives of environmental or industrial trade groups touting their positions. Sometimes there are company reps and consultants who have additional reports or data for submission which help inform the peer review. And then there are a whole lot of very angry and emotional people from areas where oil and gas development has occurred who think they are being poisoned by hydraulic fracturing.

 

It was nice to see the Science Advisory Board’s respectful questions to the registered speakers and their acknowledgement of people’s concerns about the impacts of hydraulic fracturing on their drinking water. It was less nice to listen to the SAB members parse the words in EPA’s report. Their biggest concern is over the meaning of EPA’s finding: “we did not find evidence that these mechanisms have led to widespread, systemic impacts on drinking water resources in the United States.” The “mechanisms” being referenced are the whole industrial process involved in hydraulic fracturing from storage and mixing of chemicals on-site, to well construction, waste disposal, and the actual injection of hydraulic fracturing fluids which breaks subsurface rock in order to get better flow of oil and gas. An SAB member actually read out loud the definition of the words “systematic” and “widespread” used in EPA’s finding. This sentence in the report has been very controversial and was seized upon by both industry and environmental groups to support an agenda or detract from the validity of the report. So this SAB decided to make it a center of controversy too.

 

In the SAB’s peer review comments, they asked EPA to support their finding through scientific evidence contained within their report on hydraulic fracturing.  However, there was a dissenting opinion to the peer review comment by one of the SAB members who stated in writing:

 

“The conclusion by the EPA in the June 2015 draft Assessment report stating “We did not find evidence that hydraulic fracturing mechanisms have led to widespread, systemic impacts on drinking water resources in the United States” is accurate, clear, concise, unambiguous, and supportable with the facts EPA has reviewed.”

 

I would wholly agree with the dissenter. As the conference call laboriously progressed, it became clear some of the SAB members had also come to the same conclusion. The EPA didn’t say there were no cases of impacts on drinking water from hydraulic fracturing. The EPA just said based on their analysis of available data, impacts on drinking water as a result of hydraulic fracturing were not widespread or a regular occurrence. If you read further in EPA’s report, they state there are localized cases of drinking water contamination after hydrofracturing has occurred in an area. These cases have tended to be in areas where there were spills, poor cementing of casing, or poor waste disposal practices. EPA further states in their report that there are many existing mechanisms which could cause contamination of groundwater during hydraulic fracturing:

 

“we conclude there are above and below ground mechanisms by which hydraulic fracturing activities have the potential to impact drinking water resources. These mechanisms include water withdrawals in times of, or in areas with, low water availability; spills of hydraulic fracturing fluids and produced water; fracturing directly into underground drinking water resources; below ground migration of liquids and gases; and inadequate treatment and discharge of wastewater.”

 

I hope the SAB can come to some conclusions and finish their review comments as the result of the call. The EPA process allows for dissenting opinions and they are generally included in Appendixes to an SAB’s review. Further discussions will just continue to delay a final report from EPA on the impact of hydraulic fracturing to drinking water sources.

 

It is not unusual to have differing views of what conclusions can be reached based on data from scientific research. Generally such differing views are a result of uncertainty in the data or a poor presentation of the research results. The latter case seems to be what is driving this SAB’s elaborate discussions involving the very meaning of words. It’s time for this SAB to wrap it up and send their peer review forward.