“Frac hits” sounds a little bit like a “best of album”, maybe a “best of album” for the oil and gas industry. But no, frac hits are something the oil and gas industry doesn’t want. Why? Because when a frac hit occurs then it means the horizontal fractures produced during hydraulic fracturing of a well have either intersected a nearby (offset) well or the fractures that were produced by hydraulic fracturing in a nearby well. How does an oil and gas operator know there has been a frac hit? Well the operator of the nearby well is going to be sure to let them know, because it often reduces the production of oil and gas and raises the pressure in the wellbore of their well. It can also introduce hydraulic fracturing fluid into a nearby well, which then may travel up the borehole and spill out on the surface. An increase in pressure, as well as the extension of fractures into the rock formation around a nearby well, can also damage the casing and cement. Cemented casing protects overlying rock formations from oil and gas coming up the sides of the well and possibly getting into groundwater. So a frac hit is not particularly popular in the oil and gas industry.

Frac hits occur more often when oil and gas wells are located close together. The Environmental Protection Agency in their 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.” – states most frac hits occur when wells are less than 1100 feet from one another. But frac hits have also occurred in oil and gas wells up to 8422 feet away from a well being hydraulically fractured. That’s over a mile away.

Most frac hits are located in areas where the oil and gas rock formation is shallow, because predominantly horizontal fractures are formed. Deeper rock formations develop predominantly vertical fractures. Rock formations at depth are under greater vertical pressure from the overlying rock formations, which results in more upward extension of fractures. Shallower formations don’t have much in the way of vertical pressure from overlying rock, so they fracture outward or horizontally.

Just like producing oil and gas wells, nearby abandoned wells can be affected by hydraulic fracturing. Abandoned wells are old wells which are no longer used. They may have been plugged with cement. Other wells were often just left with open boreholes. It depends on the wells age and what the state regulations required at the time of abandonment. For example and according to EPA:  Pennsylvania’s abandonment regulations for oil and gas wells were not issued until 1957. The state’s records show there were 176,000 oil and gas wells abandoned prior to 1957. I was surprised at the number of wells. You never think of Pennsylvania as being a major oil and gas state, even though the first oil and gas well in the United States was drilled there. In fact, the state’s records show that around 300,000 oil and gas wells were drilled in Pennsylvania prior to 1957. So only a little over 100,000 wells would have been properly plugged under state regulations. These old abandoned wells are sometimes near the new wells being drilled today in Pennsylvania. Old wells, even when they were plugged with cement, are probably now deteriorating. Nothing lasts forever, especially cement and steel casing.  So if one of these old deteriorating or open borehole wells is intersected by new hydraulically induced fractures, then some interesting things can occur. For example EPA cites an abandoned well in Tioga County, Pennsylvania which received a frac hit as a result of a newly drilled gas well being hydraulically fractured. The abandoned well produced a 30 foot geyser of brine for more than a week.

So how do frac hits affect water resources? Although not a major pathway for gas or contaminants to enter drinking water zones, EPA’s research shows frac hits are a potential concern in areas where shallow oil and gas is being developed, producing wells and abandoned wells are abundant, and a groundwater source is being actively used by households. In addition, if surface spills from frac hits occur then contamination of nearby surface waters and shallow groundwater may also be a concern.

There are many complaints about hydraulic fracturing, some of them real and some of them imagined. Complaints include everything from too much noise due to trucks and compressors used at hydraulic fracturing sites in the Dallas suburbs, to sudden entry of flammable methane into drinking water wells in Pennsylvania. So the impacts of hydraulic fracturing on the availability of freshwater for other purposes may seem trivial for people dealing with the immediate impacts disturbing their lives. But for some western states, the competition for water in a dry climate can be significant and a cause for concern. After all, there are few surface water resources in arid climates and the surface waters which exist are often fully utilized for domestic drinking water, agriculture and existing industry. People who live in dry climates sometimes rely heavily on groundwater, which is also a limited resource. A new use of groundwater for hydraulic fracturing can potentially impact an aquifer being used by households, farmers, and existing industrial operations.

How much water does a hydraulic fracturing operation need? The U.S Environmental Protection Agency’s Final Report on Impacts from Hydraulic Fracturing Activities on Drinking Water, states the median volume of water used per well is 1.5 million gallons. According to EPA, the average family of four uses about 400 gallons of water for domestic uses a day or 146,000 gallons a year. So hydraulic fracturing an oil and gas well uses about 10 times the amount of water a family uses in a year. Of course the 1.5 million gallons is the median, which means half of the wells being hydraulically fractured used less water and half used more. The amount of water used per well is dependent on the type of rock formation being fractured and whether it is a vertical well or a horizontal well. Fracturing shale requires more water than fracturing sandstone. Oil and gas wells which have been drilled horizontally require more water to fracture the rock than vertical wells.

Where does all this water come from? In the east, it mostly comes from surface water. For example, EPA’s report shows that in Pennsylvania and West Virginia about 90 % of the water used in hydraulic fracturing comes from surface waters like rivers and streams. In the west, the water for hydraulic fracturing comes mostly from groundwater. For example in Texas, 50 to 100 % of water used in hydraulic fracturing is sourced from groundwater. EPA says nationally, only about 5 % of water used in hydraulic fracturing is reused. So basically, the oil and gas business is using almost exclusively fresh water resources for hydraulic fracturing. Nationwide in 2012, the oil and gas industry used 52 billion gallons of water across 20 states to hydraulically fracture their wells. EPA says this is a small number compared to water being used for other purposes, such as drinking water and irrigation. Nationally, less than 1 % of water usage is for hydraulic fracturing.

But in certain areas, especially the dry western states, the percentage of water usage for hydraulic fracturing is greater. Of 401 counties reporting water usage data by the oil and gas industry, there are 26 counties where 10 % or more of the water usage in the county is for hydraulic fracturing.

This is where I have to scratch my head a little bit and wonder why EPA wanted to compare the use of a water resource for hydraulic fracturing against the use of the water for other purposes. In a county with no lack of water resources, the comparison makes no sense as there is abundant water for new uses. In a county with limited water resources, the comparison makes no sense either as there is little water for any use. Most of the counties where the use of freshwater for hydraulic fracturing is large compared to other uses, depend on groundwater. As mentioned above, groundwater is a limited resource. In the arid west, new water entering an aquifer is often less than what is being pumped out of the aquifer for domestic, agricultural and industrial uses. There are many aquifers in the mid-west and west which are being depleted as a result of over pumping of the groundwater. Sometimes fresh groundwater in certain areas of the west is being pumped so much that salty water from other aquifers is beginning to intrude into the freshwater aquifer. As a result, some towns have had to build desalination plants in order to provide people with drinking water.

I suppose the EPA wants to use this comparison to say overall there is little impact nationally on water usage due to hydraulic fracturing. But that only tells part of the story. After all, hauling water long distances adds to the cost of hydraulic fracturing. So water tends to be sourced fairly close to the oil and gas wells. If the source is a nearby stream then taking 1.5 million gallons from it can certainly have some impacts to the local flora and fauna and to people using the water downstream. EPA’s report points this out as a concern in Pennsylvania. Fortunately in that state, there is some government regulation of stream flows to limit impacts from water withdrawals.

Ditto, there is a concern where groundwater resources are limited, like in Texas and North Dakota. Again the water for hydraulic fracturing is sourced locally, usually by drilling a water well nearby. If groundwater is pumped significantly for use in hydraulic fracturing, it may affect the quantity of water available from the aquifer for other uses.  Although this may be happening in only a small number of counties, water managers have expressed concern about the potential impacts to households and farmers using the same groundwater aquifers as those now being utilized as a source of water for hydraulic fracturing. Water managers in a number of counties in Texas and North Dakota are having to make some hard decisions. For example, in North Dakota there was a concern among water managers about the increased pumping of groundwater from the Fox Hills aquifer for use in hydraulic fracturing. They feared that over pumping the aquifer for this new use would end up destroying the artesian flow of the groundwater. Artesian flow means the groundwater rises to the surface (without the aid of an electric pump) as a result of the natural pressure on the aquifer from overlying rock. This is important in rural areas where you don’t have a lot of electric lines to run a pump. In 2012, the state worked with the Corps of Engineers on a study to determine the availability of water for hydraulic fracturing from a reservoir on the nearby Missouri River as a replacement for the groundwater. As a result of the study, the Corps of Engineers determined 32.6 billion gallons of surface water from the reservoir could be made available for the oil and gas industry and for other municipal and industrial uses.

So the issue of impacts to drinking water resources from the acquisition of water by the oil and gas industry for use in hydraulic fracturing is a local one. The use of national water usage numbers is probably not a significant way to express the impacts of hydraulic fracturing on drinking water resources.

I started reading the recently issued (December 13, 2016) final report from the U.S. Environmental Protection Agency (EPA) – “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). I found the report to be significantly changed from the draft report issued way back in June of 2015. It is less a scientific report now and more of what the document was intended to be – a report to Congress on the impacts of hydraulic fracturing, if any, on drinking water resources. It hasn’t been “dumbed down” for that purpose, as I suppose a member of Congress will never actually read through the report, but it has been made much easier to read with far less science “jargon”. There is also not as much data and discussion on how EPA reached the conclusions in the report. But there is sufficient within the report, which covers a wide range of impacts from water acquisition to chemical toxicity, to dwell on it for some time in a series of posts. Otherwise, today’s post would be about twenty-five pages – a little long for anyone these days to sit down and read.

I will however write you a little summary of the report and you can follow-up in the next few months with my more detailed reviews of individual chapters within the report – the first of which I will post next week. Another reason I want to spread the wealth on the information in this report is because frankly, I have a lot of questions about the data and analysis in the report. I’m going back to many of EPA’s sources cited in the report in order to check the content of those sources so I can better understand the analysis. I was able to attend EPA’s webinar on the report held December 14, 2016. During the webinar EPA explained a few of the discrepancies between the original draft and the final. For example, the report no longer contains the phrase “studies found no widespread contamination of drinking water resources by hydraulic fracturing.” The reason EPA gave for the deletion of this phrase was due to comments from the Science Advisory Board, which reviewed the report, asking EPA to “quantify” this statement. Quantify in this case, apparently means provide exact numbers nationwide on where surface and groundwater have been contaminated during hydraulic fracturing. Since there are no databases containing this type of information, EPA could not reasonably provide such quantification and therefore decided to leave the phrase out of the current report.

Basically EPA said: hey, nobody is out characterizing the drinking water sources in an area before and after hydraulic fracturing occurs, so we can’t really say much about whether hydraulic fracturing is causing widespread drinking water contamination or not. Lack of this type of information is one of the many “data gaps” EPA identified in the report. Since the purpose of the report was to determine if hydraulic fracturing is impacting drinking water sources, I really kind of have to say: huh, are you kidding me, you’ve been conducting this study for six years and all you can say is (I quote here from the final report): “significant data gaps and uncertainties in the available data prevented us from calculating or estimating the national frequency of impacts on drinking water resources from activities in the hydraulic fracturing water cycle. The data gaps and uncertainties described in this report also precluded a full characterization of the severity of impacts.”

I would say there was something seriously wrong with the design of the work plan for the report, if it wasn’t for the fact, EPA didn’t follow the work plan in its entirety. For example, EPA was supposed to conduct pre- and post-hydraulic fracturing characterization of drinking water resources. These studies did not occur, which resulted in the major data gap mentioned above. Other data gaps resulted in part from the databases EPA used. They provided such significant inability for EPA to make conclusions on the nature and extent of any possible contamination; it is now worth while asking: why were they used in the first place.

Well, I better provide a summary now, or this post is going to turn out to be twenty-five pages just by itself. I guess I’ll start where I ended in my last post, when I wrote: “the major findings made by EPA were rather self-evident and didn’t need a six year study.”  Let’s take the first category: water acquisition. Water is a major component of hydraulic fracturing fluid (90 – 97% by volume) so the water used for making up the fluid has to come from somewhere. It can be a lot of water and a major question by water managers in the west has been: how is the increased use of water in hydraulic fracturing activities impacting water supplies. EPA says the median volume of water used per well fractured between 2011 and 2013 (the period of the study) is 1.5 million gallons. Of course you know “median” means half of the wells used more than 1.5 million gallons and the other half used less. It depends on the type of rock being fractured and whether the well is vertical or horizontal as to how much water is needed for hydraulic fracturing. EPA looked at water use by county and was able to determine that in most counties the amount of water used in the hydraulic fracturing of wells was less than 1 % of water use in the county; except in counties where it wasn’t. In fact, in 39 out of 401 counties with data, ten percent or more of water use in the county was for hydraulic fracturing and these were pretty much in the driest states, like Texas and North Dakota, and in counties where there’s not a whole lot of population. States like Pennsylvania in the east, where populations are greater and there is plenty of surface water (of course) showed less water is used by hydraulic fracturing compared to total water uses.

EPA’s study of contamination to drinking water sources from chemical mixing areas (where chemicals are stored on site and transported through pipes and hoses to equipment at the well where fracturing occurs) showed spills to be caused by equipment failure or human error. EPA studied 151 spills at the surface from chemical storage, mixing, and transport. Thirty percent were from the areas where fluid was stored. The median spill was 420 gallons, but the spill ranged from5 galloons to 19,320 gallons and included acids, biocides, friction reducers, cross linkers, gels, and blended fluid. Thirteen of the 151 spills reached a surface water body.

For contamination caused by the actual injection of hydraulic fracturing fluid into a well, EPA looked at a couple of different pathways: those pathways caused by newly created fractures from the process of hydraulic fracturing and pathways caused by mechanical failure or poor construction of the well being hydraulically fractured. These are two underground pathways where the hydraulic fracturing fluid could potentially flow into ground water. EPA pretty much took the information from already published studies; no new findings here.

The concern EPA has with fractures in the subsurface is that they might extend upward from the rock formation being fractured into shallower potable drinking water aquifers and create a route for hydraulic fracturing fluids to move into an aquifer. The EPA cites several studies which show fractures vary significantly in length depending on the rock formation being fractured. For example, hydraulic fracturing creates fractures with a greater median length in the Marcellus Shale of Pennsylvania than it causes in the Barnett Shale of Texas. The orientation of the fractures varies with the rock formation’s depth; fracturing at depths less than 2000 feet yields mostly horizontal fractures which don’t extend upward towards shallower groundwater zones, whereas fracturing at depths greater than 2000 feet yields mostly vertical fractures. EPA cites another study indicating there is a greater likelihood for upward migration of hydraulic fracturing fluid into groundwater resources when there is less vertical separation between the rock being fractured and the rock containing the groundwater.

In the report, EPA has some actual cases they have cited where well construction and mechanical failure causing contamination, but again the number of hydraulically fractured wells where this type of contamination pathway has occurred cannot be quantified

Another pathway EPA looked at to determine its potential for contamination of drinking water sources was the spillage of water containing hydraulic fracture fluid at the surface. When wells are injected with fluid to fracture the rock, high pressures are applied to the well at the surface. After the fractures are formed, the pressure on the well is released and a lot of the fluid put down the hole comes back up to the surface. Normally the water is collected and contained at the surface in tanks. But EPA was able to discern a number of cases (225) from 2011 to 2012 where there were spills of this fluid. Usually spill volumes were small – 340 to 1000 gallons – but there were at least 12 spills greater than 21,000 gallons, one of which was 2.9 million gallons. Thirteen percent of the spills reached surface water.

The collected hydraulic fracture fluid has to be disposed of eventually or reused. Where disposal options are limited, EPA shows more of the fluid is treated and reused. For example, in the past in Pennsylvania the collected fluid was often sent to local Publically Owned Treatment Works (POTWs) for treatment and disposal into local waterways. That all ended of course during the course of EPA’s study. The POTWs couldn’t really treat the fluid sufficiently and water with elevated level of bromide, strontium, barium and radium were being discharged into local rivers. The state environmental regulators pretty much shut all of that down, and now 90 % of the fluid is treated and reused in hydraulic fracturing. Most other states are disposing of the fluid into Class II injection wells. These are permitted wells used for waste disposal. Of course we’ve all seen some of the problems this has caused, not from contamination, but from earthquakes produced by the injection of fluid from thousands of wells into rocks with faults that are activated by all of the excess water. Use of unlined pits for collecting the fluid, instead of containing it in tanks, has also caused contamination as the fluid percolates into shallow groundwater beneath the pits. Many states have outlawed this practice now.

Basically, there’s a lot of information in the EPA report. But other than specific known cases of contamination, EPA is not able to make any sort of conclusion on how widespread contamination is (or isn’t) from the various pathways identified in the report. EPA says in the report, the data gaps are too great to make solid conclusions on the frequency of impacts to drinking water resources from hydraulic fracturing. What they mean by data gap, is simply the information is not readily available; either it is not collected (such as pre- and post fracking water quality), it’s not publically available (the toxicity data on many of the chemicals used in hydraulic fracturing fluid), or the information is just way too difficult to put together (for example, the surface locations of all wells being hydraulically fractured and the locations of the associated wastewater management).

EPA can only make some very obvious conclusions on what can cause impacts to drinking water sources; for example, using a lot of water for hydraulic fracturing in an area with few surface or groundwater sources can impact the availability of water for other uses, or inadequately treated wastewater can impact surface water to which it is being discharged, or disposing of hydraulic fracturing fluid in unlined pits can result in shallow groundwater beneath those pits being contaminated. All of these conclusions are already widely known and only take a modest amount of common sense to figure out. Unfortunately, common sense is not very common and all of these activities have occurred. Will state regulators address these problems with laws and regulations? Many of them already have. But the question remains unanswered of whether or not you need to shiver in your boots, if a company wants to hydraulically fracture an oil or gas well in your neighborhood.

On August 1, 2016, EPA issued the final research report: Review of Well Operator Files: Hydraulic Fracturing Operations (EPA/601/R14/004, July 2016). This new report examines the records of nine companies conducting hydraulic fracturing at 23,200 oil and gas wells between September 2009 and September 2010. Interestingly some of these oil and gas wells were hydraulically fractured more than once during that time span, so there were actually 28,500 occurrences of hydraulic fracturing over the one year period that EPA examined. EPA calls these occurrences: hydraulic fracturing jobs.

To understand the report, one must know a little bit about how oil and gas wells are constructed. After a well is drilled, a metal pipe called a casing is set into the hole created by the drill. Usually the space between the outside of the casing and the rock is filled with cement. The space between the casing and the rock is called the annular space. The annular space can be cemented for the entire length of the well or it can be cemented just in certain sections. Cement helps to protect groundwater by preventing fluids from moving up the annular space and into rocks containing protected groundwater resources. Cementing is also used to prevent gas and other fluids from moving up the annular space and causing a ruckus at the surface. Sometimes a device known as a packer is also used to seal off sections of rock containing groundwater. Packers are mechanical devises which look a lot like plungers. Before wells are hydraulically fractured, the casing next to the rock formation containing the oil and gas is perforated so the pressurized water and chemicals can enter the rock at great force and produce fractures. Occasionally however, what are called “temporary casing strings” are used for the hydraulic fracturing process instead of the permanent cemented casing. These casings really are temporary and are removed after the process is completed.

Of the hydraulic fracturing jobs EPA examined, 90 % had cemented casing, 5 % had packers, and 5 % had open holes. In 10 % of the jobs temporary casing strings were used. Temporary casing strings were used both with the open holes and in some wells with permanent cemented casings. Generally when a temporary casing string was used in an oil and gas well with a cemented permanent casing, the wells were undergoing recompletions or refractures. Recompletions are where an existing well which was previously hydrofractured at one depth is later refractured at another depth. Refractures are where the same depth in the well is being refractured. Recompletions and refractures are most often done in older wells (EPA gives a median age of 6 years for the wells examined in their report.)

This is all important knowledge, because how wells performed during hydraulic fracturing is dependent on the integrity of the safeguards like concrete, casing and packers put into place to prevent movement of fluid into protected groundwater zones. EPA calls the success of these safeguards – “mechanical integrity.” To determine the mechanical integrity of the 23,200 wells, EPA examined four different tests conducted by companies during the hydraulic fracturing process. The first type of test is a casing pressure test. This kind of test is conducted before the well is hydraulically fractured and is used to determine the mechanical integrity of the well. Basically pressures to be used in the hydraulic fracture process are applied to the well. If the well maintains its integrity then there should be no mechanical failure of the safeguards protecting groundwater during the actual hydraulic fracturing.

The second type of test is surface treating pressure monitoring. This is simply the monitoring of the pressure being applied to the well during hydraulic fracturing. If there is a sudden drop in surface treating pressure during hydraulic fracturing, it is likely one or more of the safeguards have failed.

The third test is annular pressure monitoring, which is simply the monitoring of pressure in the annular space during hydraulic fracturing. Changes in the pressure in the annular space should tell you if the wells safeguards have been breached.

And the fourth test is microsesimic monitoring, where monitors are set out to determine the extent of fracture growth in the subsurface. Microseismic monitoring can tell you if vertical fractures are long enough to intersect groundwater zones above the hydraulically fractured rock area.

As you can imagine, it was kind of hit or miss as to what sort of testing had been conducted at the wells. Two or more tests were conducted at 76 % of the 28,500 hydraulic fracturing jobs EPA examined. Casing pressure tests were conducted at 57 % of jobs, surface treating pressure monitoring at 97 %, annular pressure monitoring at 53 %, and microseismic at 0.5 %. So other than measuring surface treating pressure during the actual hydraulic fracturing process, there is simply not a lot of data being collected. In fact the annular pressure tests were so frequently insufficient; EPA opted not to even use the data for analysis. So we’re down to 3 tests now and one of them, the microseismic test, has very little data.

EPA relied mostly on the other two tests (casing pressure and surface treating pressure) and notes taken by companies kept during the hydrofracturing process to determine mechanical integrity of wells that had been hydraulically fractured. Reported in company notes were failure of the mechanical integrity of the well in 3 % of all the hydraulic fracturing jobs. Failures occurred in new wells (2%) and in recompletions and refractures (6%). EPA found that jobs using temporary casing strings had the largest number of failures. In fact 20 % of the jobs using temporary casing strings had some sort of failure. Failure generally meaning one or more of the safeguards failed. Now many wells of course don’t have just one casing, sometimes there are multiple casings set in the well, so failure doesn’t mean fracturing fluid escaped into a groundwater zone. In fact, EPA noted in their report that once failure was noted by a company, the job was stopped and the cause of the safeguard failure was addressed. But in 0.5 % of the hydraulic fracturing jobs, information in the companies’ files indicated fracturing fluid moved into the annular space at the location of groundwater.

EPA did learn something from the microseismic monitoring they examined. Among the 100 jobs where it was done, EPA used the data to estimate the vertical extent of fractures. It showed vertical fractures grew anywhere from 380 to 1340 feet. EPA could find no case where vertical fractures extended into the groundwater zone in the areas being hydraulically fractured. In fact EPA estimated fractures reached no closer than 5000 feet from any groundwater source.

What did EPA learn from the casing pressure tests and surface treating pressure monitoring?  In 48 % of the hydraulic fracturing jobs where casing pressure tests were conducted, the pressures recorded during the actual hydraulic fracturing process exceeded the casing pressure tests by 1000 to 1999 pounds per square inch.

Pretty interesting information. The most interesting fact to me is there were 142 hydraulic fracturing jobs out of the 28,500 jobs examined, where the mechanical safeguards in the well failed and hydraulic fracturing fluid entered groundwater zones. Is a 0.5 % failure rate of wells during hydraulic fracturing an acceptable failure rate? This will have to be determined by state governments who oversee oil and gas operations in their states and the citizens who live in the vicinity of oil and gas fields.

On August 11, 2016, the Environmental Protection Agency’s (EPA) Science Advisory Board issued their Peer Review of the EPA Draft Report on Impacts of Hydraulic Fracturing on Drinking Water. The peer review contains the Science Advisory Boards’ official comments on the EPA Draft Report. EPA announced it will use the Science Advisory Boards’ final peer review comments, other scientific literature completed since the release of the EPA draft, and public comments to complete their final report within the next few months.