Data driven discussions about gas extraction and related topics.

Updated West Virginia Marcellus Shale datasets on our DataTool


This page has been archived. It is provided for historical reference only.

Click on the map for a dynamic view and for more information.

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I have posted updates of West Virginia’s Marcellus Shale permit and well data onto our FracTracker DataTool. The information was downloaded from the West Virginia Department of Environmental Protection (DEP) Office of Oil and Gas website.

I searched the DEP website for Marcellus Shale wells and found 1,463 different locations. When I looked at the at permit data, I got almost 12,000 records for 1,464 Marcellus Shale distinct wells.  It seems difficult to believe that all but one permitted well has already been drilled, and a closer look at the data shows that really can’t be the case.

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In this dataset, there are 1,338 Marcellus Shale permits issued (green), 21 permits canceled (red), and 39 permit applications returned (yellow).

Of those permit records, only 1,338 are listed as having the permit issued. Unlike the Pennsylvania well list which includes only spuded wells, it seems that the West Virginia DEP thinks of the well list as a summary of the permit list, rather than a list of sites that have actually been drilled. In addition, West Virginia does not include the spud date on their oil and gas well data. Instead, they use the date for the last permit that was received for the well, which in no way indicates whether drilling activity has commenced.

I have contacted the West Virginia DEP for clarification on this point, and will share their response as a comment on this space.

Utah Wells and Violation Discussion


Utah Oil and Gas Industry Overview


This page has been archived. It is provided for historical reference only.

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Utah Oil and Gas Wells.
Click on the map for more information.

I pursued oil and gas data from Utah due to the accessibility of the relevant information, and because a map of major shale gas plays indicate several formations of interest in the state, notably the Hermosa and Mancos Formations.  However, I learned from Utah’s Oil and Gas Permitting Manager and Petroleum Geologist Brad Hill that while there has been discussion of extracting gas from shale formations, currently none of the wells in the state are producing shale gas. On the other hand, he did indicate that most of the wells in the state had been stimulated to some degree with hydraulic fracturing.

The state is relatively new to the oil and gas industry. Although only one well from 2008 is listed as a test well, it seems fair to conclude that at the very least, the three total wells from 2003 through 2005 should fall in that category as well, even if they are classified as gas wells.

Horizontal Wells


For a state where most of the wells are hydraulically fractured, there are very few horizontal wells.  It is also noteworthy that most of the wells that are drilled horizontally are oil wells, not gas.  While 3% of oil wells are permitted to drill horizontally, the same is true for only 0.8% of gas wells.  The reason for this is not clear at this time.

Geographic Information

Geographically, Uintah County is by far the most active portion of the state for natural gas permits, while Duchesne County is similarly dominant for oil drilling activity.  Together, Carbon County and Uintah County account for about 93% of the gas permits, while Duchesne County and Uintah County combine for 92% of the oil wells.


Violation Information


Violation data from the Utah Division of Oil, Gas, and Mining is not posted online, so I submitted a request, and received the data promptly.  That dataset includes comments as to what happened to cause the violation, as well as mitigation efforts to date.  For the moment, however, we are most interested in an overview of the data.  I have therefore condensed the violations into eight categories for ease of use.

Statewide, there is a gas leak for just over 1% of the permits issued, and for Uintah County, where the vast majority of the gas operations are, that figure is just 0.4%.  But in Emery County, there is a gas leak violation for 16% of the permits issued, and Duchesne County that figure is 22%.
The reason for this disparity is not provided, however the numbers do seem to suggest that violations of this type are more frequent where the gas drilling operations are relatively sparse.  I mentioned that Carbon and Uintah Counties together account for 93% of the gas operations in Utah.  If we consider those two counties to have an established gas industry with the rest of the state being exploratory in nature, we see a dramatic difference in the frequency of gas leak incidents.

Pennsylvania Wells and Violation Discussion


Pennsylvania Oil and Gas Industry Overview


This page has been archived. It is provided for historical reference only.

Oil and Gas Wells in Pennsylvania since 1998. Click on the image for more details. [image removed]

The extraction of oil in Pennsylvania has been ongoing since before the Civil War, and the natural gas industry is also well established. The boom in production due to the hydraulic fracturing of gas from the Marcellus Shale formation is, however, quite recent.

A proper analysis of the oil and gas industry starts with the question, “How many wells of each type are there?” Unfortunately, the figures for non-Marcellus Shale and total wells are approximate. On their website, the Pennsylvania Spatial Data Access (PASDA) maintains a list of over 123,000 oil and gas locations in the state, based on Department of Environmental Protection (DEP) data. Through our efforts, CHEC has found over 6,000 more locations from permit information available on the DEP website, bringing the total of oil and gas locations to over 129,000.

Some of these 129,000 locations were undoubtedly never spudded, but that level of information is not available at this time. There is data as to which Marcellus Shale wells have been spudded, as all of the Marcellus Shale wells are recent enough to have digital information about them on the DEP website.

I compiled this information about drilled wells from information that is on the DEP website, and it indicates that there are only ten wells that were drilled horizontally that were not extracting from the Marcellus Shale formation.  I have seen comments in violation data indicating that wells not flagged as Marcellus had become Marcellus wells by drilling deeper. I do not have data to suggest that this situation accounts for all ten horizontal wells that are not flagged as Marcellus Shale, but I would not find that surprising.

Violation Information

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Fire in Hopewell Township PA – Atlas Energy drilling site 3-31-10

In the past few days, the DEP has posted oil and gas violation data on their website. Several weeks ago, the DEP provided CHEC with a comprehensive list of 9,370 violations in the period between January 1, 2007 and September 30, 2010. This is more than ten times the number of violations that has been obtained from both Utah and West Virginia, although the nature of this list is also far more complete than that of the other two states. Additionally, Pennsylvania has a more extensive oil and gas industry than either of the other two states.

For example, the table above shows over three thousand administrative violations, one thousand instances of failing to plug a well, and four hundred cases where the well operator failed to restore a site after the conclusion of drilling operations. The nature of the violation information from the other two states leads me to suspect that their violation lists were simply compiled differently, and that these problems that the Pennsylvania DEP regulators have seen so much of are not absent in the other states.

I have condensed the original list of 109 violations categories into 12 in order to facilitate analysis. Some of these distinctions were relatively simple to collapse.  For example, wastewater spills and brine spills clearly belong together. Other examples were less clear. One of the original categories was “Improper storage of residual waste”, which does not explain whether or not a spill had occurred. For that reason, it was included with, “Inadequate pollution prevention”, although the violation might well have been issued after an impoundment overflow.

Where are the Violations?

In terms of geographical distribution, we see that three contiguous counties in the northeast quadrant of the Commonwealth—Bradford, Susquehanna, and Tioga—account for a majority of the Marcellus Shale violations, Two northwestern counties—McKean and Venango—have noticeably more violations than the rest of the counties in terms of oil and gas operations that are drilled into other formations.

Violation Analysis

For states where the oil and gas industry is relatively recent, it is straightforward task to compare violations to the number of permits or spudded wells. With the long history of mineral extraction in Pennsylvania, the results of that comparison here is somewhat problematic.  For example, while the 1,111 instances of failing to plug a well issued during this 45 month timeframe is a frankly staggering total, only five of those were for Marcellus Shale wells. This makes sense, as the more recent Marcellus wells are more likely to still be productive, while a violation for an uncapped well could potentially be issued for a long abandoned well that was recently discovered.

The point of bringing up this example is to suggest that due to the long timeframe of oil and gas operations in Pennsylvania, a straightforward comparison of Marcellus Shale to non-Marcellus Shale violations by the number of wells of each type is probably misleading. And, as mentioned above, we are not altogether clear on how many conventional wells that there are in the state in the first place.

However, if we look at the number of violations per well against the more limited scope of wells which are in violation, some interesting trends come to light, and the issue of severely skewed results due to the antiquity of the conventional oil and gas industry in the state seems effectively mitigated in this analysis as well.

To be clear, this does not suggest that there are an average of 2.56 violations per well in Pennsylvania. It does indicate that when the DEP sees a situation in which violations must be filed, there are typically more than one problem at a time. As the data above shows, wells drilled into the Marcellus Shale have a higher number of violations per offending well than do those in other formations, and the horizontally drilled Marcellus wells have more still.

West Virginia Wells and Violations Discussion


West Virginia Permits and Wells


This page has been archived. It is provided for historical reference only.

According to their website, the West Virginia Department of Environmental Protection Office of Oil and Gas is responsible for over 55,000 active and 12,000 inactive oil and gas wells in the state. To obtain a scope of the Marcellus Shale activity, I queried that state’s online permit and well databases on November 1, 2010.

The search of permitting data yielded 11,836 records, however a closer look at the data shows that there have been only 1,474 permit applications received from 1,464 wells, with the rest of the dataset providing detailed information about the same locations. Of the total number of applications, a total of 590 are horizontal. There are a total of 1,338 permits that have been issued, of which 533 are horizontal.

From the well database, there are 1,463 Marcellus Shale wells, 1,334 of which are gas wells, one is a commercial brine disposal well, and the remaining 128 wells of an unspecified type. Since as of November 1, 2010 there are only 1,338 permits issued for the Marcellus Shale, those unspecified wells are a curious presence.
Results of Permit Applications. Green dots are approved permits, yellow dots are permits that have been returned, and red dots are rejected permits. Click the map for more information.

Violation Data

Unlike other states in which violation data has had to be requested, the West Virginia DEP has separate spills and violation databases available on their website. The spills database includes 463 records between the dates of January 1, 2000 and September 30, 2010, while the violation data includes an additional 245 records from the same time frame.

Even together, these totals are less than one tenth of the number of violations that have occurred in Pennsylvania since 2007, although these lists do no not seem to include much of the administrative and abandoned well violations that are so prominent in the Pennsylvania data. I should also note that the 67,000 current and abandoned wells that West Virginia oversees is roughly half of Pennsylvania’s 129,000 known oil and gas locations.

I condensed the original list of 134 different spill types into six categories to facilitate analysis. Most of the instances of merging categories were straightforward. For example, brine spills and wastewater spills clearly belong together. A few, such as “Substance from gas well” required some degree of guesswork.

The other violation database includes the relevant West Virginia legal code. Most of the categories seem logical, however a few, such as “Libraries” and “Religious, Educational, and Nonprofit” seem to be illogical oil and gas violation categories. Libraries may well be a mistake, having come up only once, but with 41 instances, it seems likely that the latter legal chapter has some relevant code for the oil and gas industry.

As with the spills data, this dataset includes numerous entries with multiple violations, resulting in a total number of violations that is higher than the number of records in the online database.

New Violation Datasets at our DataTool


This page has been archived. It is provided for historical reference only.

Three new datasets have been added to our DataTool: Utah Oil and Gas Violations, West Virgina Spills, County by Year, and West Virginia Spills Data.

The Utah dataset contains information including violation type, and oil and gas related injury and fatality records.  The West Virgina Spills, County by Year dataset is a set up to be easy to visualize, however, those interested in analyzing the West Virginia data itself will want to look at the West Virginia Spills Data dataset.

Earlier, we posted a separate WV Marcellus and O&G Violation by County dataset. I suspect that the West Virginia data is incomplete, due to the relatively small number of records.  There are 463 records of spills and 259 other violations since January 1, 2000, for a total of 722 offenses.  Compare that to the dataset from Pennsylvania, where there are over 9,300 violations recorded, and those are all since January 1, 2007.

Pennsylvania Violation Data


This page has been archived. It is provided for historical reference only.

The Pennsylvania Department of Environmental Protection (DEP) responded to our request for oil and gas violation information with a list of 9,370 violations from January 1, 2007 through September 30, 2010. That works out to almost seven oil and gas violations statewide per day. Certainly, the DEP has been taking its job very seriously in trying to regulate the oil and gas industry within the Commonwealth.

At the same time, it makes one wonder what violations occur that the DEP is not aware of.

A Closer Look at the Numbers

The 9,370 violations came from a total of 3,661 wells. Of that total, 2,075 violations are flagged as Marcellus Shale, from 592 distinct wells. And of the Marcellus wells total, there were 1,497 violations from 399 wells that were flagged as horizontal wells. All horizontal wells in this dataset are also Marcellus Shale wells.

That means that for non-Marcellus Shale wells, there were 7,295 violations from 3,069 wells, for a frequency of just 2.38 violations per well. The highest frequency of violations per well was 37, for API# 131-20020, a horizontally drilled Marcellus Shale well in the town of Washington in Wyoming County, PA.

In terms of average violations per well, the reported data indicates 2.38 violations per non-Marcellus well, and 3.51 violations per Marcellus well, for an overall average of 2.56 violations per well.

This graph shows the mean number of violations per well type in
Pennsylvania.  This is based on a list of 9,370 violations provided by the PA
DEP from 1-1-2007 through 9-30-2010.  Please note that this reflects only wells
where violations occurred,not every well of this type within Pennsylvania.

Please keep in mind that all of these values only represent wells that have violations, and therefore it should not be construed that the average Marcellus well will have three and a half DEP violations. This certainly does, however, raise the question of why an offending horizontal Marcellus Shale well would have an average of 1.37 more violations per well than its non-Marcellus counterpart, but it does not provide the answer. Perhaps it reflects that more can go wrong on horizontal Marcellus Shale wells, or that they are more tightly regulated. Perhaps a handful of individual sites like the one in Washington have so many violations that they skew the data in some way. There could be numerous scenarios to explain the discrepancy.

Obtaining Geographic Location Information

To date, the primary means of linking oil and gas data to a geographic location has been using the dataset compiled by PASDA, which includes the information of over 123,000 oil and gas locations within the state. Unfortunately, the PASDA data was insufficient for the violation data, as there were thousands of records that did not match. I have reduced that number significantly to by adding the list of known permits since 2007 (which also includes geographic information) to the PASDA list. This process created duplicate entries, which was worked around by obtaining the average longitude and average latitude of each API number.

This process does not eliminate any errors inherent in the data. In one example that I looked at, there were three listings for one unique well number, one of which was off by 0.3 degrees of latitude, or about 20 miles. In this scenario, it would be tempting to correct the one to conform to the other two, but in reality, it isn’t clear which one is correct. And for that reason, auditing the dataset—which is now over 128,000—for errors is not especially productive. For the moment, it is sufficient to say that there are some errors present in the location data, which are hopefully minimal in scope.

Drilled Oil and Gas Locations in Utah

By Matt Kelso – Data Manager, Center for Healthy Environments & Communities (CHEC), University of Pittsburgh Graduate School of Public Health


This page has been archived. It is provided for historical reference only.

A new dataset of drilled oil and gas locations in Utah has been added to FracTracker’s DataTool (click on the snapshot of that dataset to the left to see more detail). This dataset was pursued in order to obtain more data from other shale gas fields throughout the United States. However, despite the fact that there are shale gas fields in the state, a correspondence with Utah’s Oil and Gas Permitting Manager/Petroleum Geologist Brad Hill has led to the revelation that there are currently no shale gas wells in the state. On the other hand, he indicated that most vertical and horizontal wells in Utah undergo some amount of hydrofracturing process, making the data relevant to our pursuits here at FracTracker.

Dissemination of Information

From the perspective of trying to obtain meaningful data about oil and gas operations, the Utah Division of Oil, Gas and Mining is wonderful resource. Just to give an indication of the breadth of the scope of what they have to offer, go to the Oil and Gas Well Log Search, set the three boxes to “API Well Number”, “LIKE”, and “43” (which is Utah’s state code), and you get a list of wells in the state, complete with associated well logs that can be viewed and downloaded. In Pennsylvania, you would have to file a Right to Know claim to get access to some of these documents. The small sample of scanned source documents that I have looked at in Utah has included typewritten notices from the 1960’s. One of the files had over 30 pages of documents.
In addition to having an abundance of information on their site, the workers that I have dealt with at the Division of Oil, Mining, and Gas have been extremely useful in obtaining additional information. My initial query to Don Staley of that department was replied to within 20 minutes, and he contacted the Petroleum Geologist of his own volition to make sure that the information that was given to me was clear. They have set the standard for public service by a governmental regulatory agency, as far as I am concerned. Texas was also helpful, but only some of their information is available free of charge.

Geocoding Issues

Most people are familiar to some extent with the basic longitude and latitude system. The grid that the two values combine to make, known as a graticule, allows for the identification of unique locations on the planet. It is not, however, the only means of identifying unique locations.

A system used by Utah and by many of the other western states is known as the Public Land Survey System, or PLSS. This system was conceptualized by Thomas Jefferson and dates to the Land Ordinace Act of 1785. In essence, it creates a series of six-mile wide horizontal bands known as Townships, and six-mile vertical bands called Ranges. These intersect to create a six-by-six mile box (see image right), with a name of something like “Township 5 North”, “Range 8 West.”  This is further divided into 36 sections, each one-mile square. This can be further subdivided into quarters, and then quarters of that, so that a location could be recorded as the northeast quarter of the southeast quarter of Township 5 North, Range 8 West, Section 5 (or NE1/4 of SE1/4 of T5N, R8W, Sec. 5 for short).

This discussion is relevant here because in parts of the Utah Oil and Gas website, location information comes up in this format. To obtain the locations for the drilled wells in the state, it required a convoluted process of finding a map of the 1-by-1 mile section boxes, then finding the midpoint of those boxes with GIS tools, and finally correlating those points to the original dataset. Since the midpoint of a 1-by-1 mile box is about 0.70 miles to each corner, that is the margin of error for the location of these datapoints. For most uses, that shouldn’t matter.

After completing these conversions, I have found elsewhere on the site latitude and longitude data, as well as Universal Transverse Mercator (UTM) values, which is yet another means of finding unique places on Earth. I have not yet determined whether that has all of the information from the dataset that has been posted, but if so, then more accurate location information will follow shortly.

Do the natural gas industry’s surface water withdrawals pose a health risk?

By Kyle Ferrar, MPH – EOH Doctoral Student, University of Pittsburgh GSPH


This page has been archived. It is provided for historical reference only.

Wastewater discharges are regulated through national pollutant discharge elimination system (NPDES) permits, and are based on the concept “the solution to pollution is dilution.” However, what happens when the diluting capacity of a river diminishes? If the natural gas industry will be producing 20 million gallons per day (MGD) of wastewater in 2011, but only retrieves 20% to 70% of the water used to drill and hydrofracture a well, over 28.5 to 100 MGD must be withdrawn from water resources1.
Water withdrawals for the natural gas industry are permitted through the Pennsylvania Department of Environmental Protection (PA DEP) with the approval of the Department of Conservation and Natural Resources (DCNR). As water is withdrawn, the volumes of stream flow decrease. Water withdrawals must be conducted responsibly, so that the volumes of stream flow are not impacted. Decreasing flow decreases the assimilative capacity of waterways to dilute pollution, such as TDS. In the late summer and fall, lack of precipitation causes drought conditions, and accounts for the lowest flow periods each year. But in 2008 through 2010, flow in parts of the Monongahela River have been less than half than what they are typically, at this time of the year, according to the Army Corps of Engineers2.

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Figure 1. Permitted surface water withdrawals in Pennsylvania are shown on the map, active as of April 2, 2010.

Figure 1 shows the permitted water withdrawals in Pennsylvania for commercial, industrial, and agricultural use, as well as the permitted water withdrawals for the oil and natural gas industry. There is a multitude of groups that rely on water withdrawals for their livelihood, including the oil and gas industry, labeled as red stars. The capacity of river flow to dilute pollutants to safe levels also depends on river flow, and has precise limits. The current assimilative capacity for pollution and TDS in the Monongahela River is showing signs of saturation, and is characteristically oversaturated during the dry season. Monongahela River communities are already urged to rely on bottled water rather than their own municipal tap water, for certain periods of the year. Therefore, at the current rate of natural gas industry water withdrawals, there is no longer any room left for further economic development of water resources in other sectors of industry within the Monongahela River basin, if public health is to be conserved.

The current water management practices of the natural gas industry during the regional dry season are likely to have contributed to higher TDS concentration in the Monongahela River. New regulations for treatment and discharge of wastewater are designed so that the wastewater does not result in a severe impact, but the issue of mediating sustainable withdrawals has not been addressed. The majority of the pollution in the Monongahela River is still suspected to be caused by issues of legacy pollution, such as extensive acid mine drainage within the watershed3. On the other hand, the water withdrawals in the Monongahela River watershed are potentially causing a cumulative impact on flow volume in the river that magnifies all forms of pollution by increasing the pollutant concentrations. Much more research needs to be conducted on this issue, to ensure safe and sustainable permitting practices for water withdrawals.


  1. Penn State University, College of Agricultural Sciences, Agricultural Research and Cooperative Extension. 2010. Shaping proposed changes to Pennsylvania’s total dissolved solids standard, a guide to the proposal and the commenting process.
  2. Puko, Tim. Silty Salty Monongahela River at risk from pollutants. Tuesday August 24, 2010. Pittsburgh Tribune Review.
  3. Anderson, Robert M. Beer, Kevin M. Buckwalter, Theodore F. Clark, Mary E. McAuley Steven D. Sams, James I. Williams, Donald R. 2000. Water Quality in the Allegheny and Monongahela River Basins. USGS circular 1202.

Marcellus Shale Production Data – The Good, The Bad, The Ugly

By Matt Kelso – CHEC Data Manager


This page has been archived. It is provided for historical reference only.

As of September 7th, 55 of 73 drilling companies that operate in the Marcellus Shale field in Pennsylvania have reported their production data, which has been compiled into a single Excel spreadsheet by the Pennsylvania Department of Environmental Protection (PA DEP). Click here to see the list. This dataset is quite raw, and far from complete. Even so, a review of the preliminary data is a worthwhile exercise, as it gives us some insight into the industry that we were unaware of before.

Production Overview

Before getting into the specifics of production, a few overall numbers for the state would be appropriate. Altogether, there were 5,678 rows of data, representing 3,954 distinct wells. Only 3,076 of the rows have production data.

Production refers not only to oil and gas, but to waste products, as well. The spreadsheet tracks production data in the following categories: Basic Sediment, Brine, Condensate, Drill Cuttings, Drilling, Frac Fluid, Gas, and Oil. It is not known whether the final release of the data, which is scheduled for November 2010, will have a greater or fewer number of categories. The data comes unsorted and without explanation, so the units of measure for all categories are not entirely certain at this time.

Basic Sediment

The first category, Basic Sediment, is a solitary occurrence, and the volume of production is listed as 1,179. Whether this reported amount is miscategorized, irrelevant, or just exceedingly rare is not known at this time. The exact nature of what Basic Sediments refers to is not clear at this time, either.


Eight hundred-one (801) of the reported Marcellus wells produced brine, with volumes ranging from 2 to 24,165. For the moment, there is no choice but to assume that all of this is reported in the same unit, which will be assumed to be gallons. To give an idea of distribution, some arbitrary comparisons have been made here as well: 149 of the 800 wells have brine production of 100 or less, and 12 of them have production of 10,000 or more. The total brine production reported statewide was 1,196,001.19.


Condensate is presumed to be waste water from the process of removing gas that comes to the surface embedded in water, which must then be extracted in condensate tanks. Of all of the wells in the state, 124 reported on Condensate, but the vast majority of those came back with a volume of zero. There are eight wells that reported non-zero volumes, and those range from 18.08 to 113,096.34 for a total of 187,855.85 units.

Drill Cuttings

Drill Cuttings is the term used to describe the rocks and sediments that are removed in order to make the original well. There are ten items in this category, which range in value from 250 units to 8,527, for a statewide total of 15,594.07 units. The measure of unit is again unknown.


The distinction between Drilling and Drill Cuttings is not clear at this time. Four hundred ninety-seven (497) wells reported production in this category, yielding between 0 and 27,200 units of product for a statewide total of 898117.53. As a point of comparison, 291 of the 497 wells produced 1,000 units or less, while 15 wells produced 10,000 units or more. Uncertainties about the unit of measure that were expressed in the Drill Cuttings section apply here, as well.

Frac Fluid

The following category is Frac Fluid, which should refer to the chemical additives that make up one percent or less of the solution that is injected into the wells to release pockets of gas which are trapped in the shale deposits. According to this data, however, statewide production in this category exceeds the production of Brine, which is the term usually used to describe the salty waste water that comes up from the wells that would include the Frac Fluid as a small component. We must, therefore, question whether there might be some discrepancies in the way in which different companies report their data, or whether the results are due to a simple unit of measure issue. At any rate, there are 383 wells reporting Frac Fluid production statewide for a total of 1,621,721.19 units, with individual values ranging from 0 to 32,778. Of those 383 wells, 157 produced 1,000 units or less, while 54 produced 10,000 units or more, and gallons seems like the most likely unit of measure.

Gas and Oil Production

Production by Reporting Operator

There are 872 wells with production information for gas, of which 240 wells are reporting zero gas production. Of the remaining 632 wells, production values range from 29 to 2,841,152 units for a statewide total of 179,779,048. According to, production at the wellhead level is commonly recorded in terms of thousands of cubic feet (MCF), which would put the reported production of the Marcellus Shale wells in the state at about 180 billion cubic feet (BCF) for the year. Of the 632 wells with non-zero values, 271 produced 100 million cubic feet (MMCF) or less, while 360 produced more than that amount.

There is also oil production associated with the Marcellus Shale drilling operations, and values in this category have been recorded for 385 wells in the state. Only 155 of these wells have a production value other than zero, however. Values range from 10.76 to 20,741.66 units, which are presumed to be barrels, for a statewide total of 402,253.38 barrels.

In addition to these categories, there are also 2,600 records that are included in the report but don’t have production data for any of the categories. These are distinct from items in the categories listed above with a listed production volume of zero.

A Significant Undertaking and Further Discussion

Credit should be given to the PA DEP for undertaking the project of mandating and publishing production reporting of the Marcellus Shale gas extraction industry in the state. Further credit should be given since this data was provided well ahead of the planned release date of November 1, 2010. And they should be praised for publicly listing companies that were not in compliance with the regulations that demand the production reporting in the first place (click here to see the list of 33 compliant and 40 non-compliant companies).

But when you take the time to look at the data, the thing that stands out more than anything is that it is a disorganized mess. It is clearly incomplete; all forms of production are tossed into the same column, and no units of measure are provided for anything. Compare that with the records kept by Arkansas or Texas.

9/27/10 Updates…

A non-profit stakeholder group called STRONGER, State Review of Oil and Natural Gas Environmental Regulations, Inc., recently assessed the quality of the Pennsylvania’s hydraulic fracturing oversight program and presented the results in a report. In this report, STRONGER praised the strength of the PA DEP’s waste identification tracking and reporting process – In other states, production data are being tracked more extensively, but waste data are limited at best. Along those same lines, legislation is being proposed that will require more extensive reporting obligations on the part of well operators.

Potential Shale Gas Extraction Air Pollution Impacts


This page has been archived. It is provided for historical reference only.

How Organic Compounds Contained in the Shale Layer Can Volatilize Into Air, Become Hazardous Air Pollutants and Cause Ozone Formation

By: Conrad Dan Volz, DrPH, MPH; Drew Michanowicz, MPH, CPH; Charles Christen, DrPH, MEd; Samantha Malone, MPH, CPH; Kyle Ferrer, MPH – Center for Healthy Environments and Communities (CHEC), University of Pittsburgh, GSPH, EOH department

The Center for Healthy Environments and Communities has received numerous requests for information on how Marcellus shale gas extraction operations might contribute to air quality problems throughout the PA-NY-WV region, how air quality problems might develop in other shale plays around the country, and the potential human exposure to specific air contaminants generated in these processes. We are addressing this question in a very thorough academic fashion now by looking at the industrial processes involved from site clearance, to well drilling and hydrofracturing, to gas processing and methane and byproduct transport; we are developing conceptual site models of human exposure to contaminants generated by this very complicated industry with many sub-operations.
A conceptual site model is a written and/or pictorial representation of an environmental system and the biological, physical and chemical processes that determine the transport and fate of contaminants from a source, through environmental media (air, groundwater, surface water, sediment, soils, and food) to environmental receptors (humans, aquatic and terrestrial organisms can all be environmental receptors) and their most likely exposure modes (ASTM, 2008). Again, because there are many sources and types of contaminants to understand and uncover within each gas extraction process, it will take until mid-fall to complete this study. In the meantime, here is basic information on potential air quality impacts from shale gas extraction activities.
Part I of this series explains how organic compounds in the shale layer itself can be mobilized during the hydrofracturing and gas extraction process and volatilized into the air from frac ponds, impoundments, and pits, as well as from condenser tanks, cryo plants and compressor stations – and become Hazardous Air Pollutants (HAP’s).

Part II explains how volatile organic compounds (VOC’s), which are HAP’s, form ozone in the lower atmosphere (otherwise known as ground level ozone) and uses maps generated for other regional studies of other precursor contaminants to lay a basis for formation ozone over the Marcellus area.

Part I: How organic compounds in the shale layer enter air and become Hazardous Air Pollutants

Since this article is on potential human exposure to airborne volatile organic compounds from shale gas operations, we will limit the following narrative conceptual model to how organic compounds in the shale gas layer itself can be mobilized by the hydraulic fracturing and above ground operations to become airborne and present an inhalation hazard.

An exhaustive search of the literature was done to obtain peer reviewed articles on Marcellus or other shale play flowback and produced water and concentrations of organic compounds in this water; no scientific articles were found that look specifically at organic compounds when well stimulation technology is used. Additionally, no papers were found that characterize organic compounds in flowback or produced water from Marcellus Shale wells over the region, which may vary significantly; anecdotal information suggests that wet gas containing organic compounds is an important byproduct in SW PA, whereas dry gas is more common in NE PA.

However, we can piece together good evidence that flowback and produced water from shale layers themselves contain organic compounds that could offgas into the environment when brought to the surface. First, gas-productive shale formations occur in Paleozoic and Mesozoic rocks in the continental United States and are characterized as fine-grained, clay- and organic carbon–rich rocks that are both gas source and reservoir rock components of the petroleum system (Martini et al., 1998). Gas is of thermogenic or biogenic origin and stored as sorbed hydrocarbons, as free gas in fracture and intergranular porosity, and as gas dissolved in kerogen and bitumen (Schettler and Parmely, 1990; Martini et al., 1998). Kerogen and bitumen are extremely large molecular weight and a diverse group of organic compounds that could also be broken into many smaller organic compounds during the hydrofracturing process given the high pressures used, the temperatures at depth and the chemical additives added to make the water slick. The USGS factsheet 2009–3032 states clearly that hydrofrac water “in close contact with the rock during the course of the stimulation treatment, and when recovered may contain a variety of formation materials, including brines, heavy metals, radionuclides, and organics that can make wastewater treatment difficult and expensive” to dispose of, although no supporting documentation is provided (Soeder and Kappel, 2008).

Certainly gas shales contain numerous organic hydrocarbons; we know, for example, that the Marcellus contains from 3-12% organic carbon (OC), the Barnett: 4.5% OC, and the Fayetteville: 4-9.8% OC (Arthur et al, 2008 ). A whitepaper describing produced water from production of crude oil, natural gas and coal bed methane and prepared by researchers at the Argonne National Laboratory, reports that volatile hydrocarbons occur naturally in produced water and that produced water from gas-condensate-producing platforms contains higher concentrations of organic compounds then from oil-producing platforms (see below a description of organics from oil and gas producing platforms in the Gulf of Mexico) (Veil et al., 2004). Organic components of this produced water consist of C2-C5 carboxylic acids, ketones, alcohols, propionic acid, acetone and methanol. The concentration of these organics in some produced waters can be as high as 5,000 parts per million (ppm). This study further states that

Produced waters from gas production have higher contents of low molecular-weight aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene than those from oil operations; hence they are relatively more toxic than produced waters from oil production. (Veil et al., 2004)

The authors conclude in this section that produced water contains:

… aliphatic and aromatic carboxylic acids, phenols, and aliphatic and aromatic hydrocarbons. Partially soluble components include medium to higher molecular weight hydrocarbons (C6 to C15). They are soluble in water at low concentrations, but are not as soluble as lower molecular weight hydrocarbons. They are not easily removed from produced water and are generally discharged directly. (Veil et al., 2004)

A dated but very informative paper on the contaminants in produced water in the Gulf of Mexico is “Petroleum drilling and production operations in the Gulf of Mexico” by C.S. Fang (1990). Here, “produced water” is referring to formation water or water condensed from the flowing gas mixture in the production tubing string only since these wells are not stimulated. The paper states that the largest discharge by volume from an offshore platform is from produced water. The organic compounds in the produced water come from three sources:

  1. Organic compounds extracted from the crude oil,
  2. Chemicals added to produced water or put into a producing well – such as corrosion and scale inhibitors, scale solvents, biocides, antifreeze, and oil and grease, and
  3. Impurities in the chemicals used.
Further, some paraffin’s and aromatics have moderate solubility in water; as long as oil-gas and water flow upward together these can become dissolved in water. The longer the transit time (as in deep Marcellus wells) the more hydrocarbon can dissolve into water. This paper reports finding toluene, ethylbenzene, phenol, naphthalene and 2,4-dimethylphenol in produced water and states that bis(2-ethyl-hexyl) phthalate, di-n-butyl phthalate, fluorine and diethyl phthalate have been found in produced water by the EPA. Estimated pollutant concentrations and discharges of organic and non-organic chemicals from produced water are shown in a Table 3 (below) from this paper.

The authors of this paper also found significant organic compounds in ocean floor sediments near oil and gas platforms. This of course has important ramifications for what organics are contained in frac pond sludge from on shore shale gas extraction and hint that this material should be tested using TCLP methods to see if it is hazardous waste. Certainly buried pits containing sludge could continue to offgas organic vapors from this sludge material. The table below extracted from this paper shows the organic contaminants in the ocean floor sediments.

So now that we have established the mobilization of organic chemicals in flowback and produced water, how do they get into the air which we breathe? If you remember back to your chemistry class in high school or college you may remember something known as the Henry’s Law constant. The Henry’s Law constant (H) of an organic compound determines its ability to enter the air. Compounds that have high H’s can enter the air from water easily, whereas compounds with low relative H’s enter the air less well- and they enter the air from the water phase dependant on their concentration in water, their concentration in air and the prevailing temperature and pressure. Again, remember PV=nRT (pressure times volume equals the mole fraction times the gas constant times temperature in degrees Kelvin) Hang in there, I know it is coming back to all of you. They enter the air then when the concentration of the compound in air is lower than that in water, which is generally the situation unless you live on some planet that has toxic organic vapor levels in air or next to a petrochemical plant during some crisis! And they can be envisioned as entering the air by either of two models: 1) the stagnant air-water model or 2) the circulating packet model.Using either model, the flowback or produced water that returns to the surface and goes into a frac pond-pit or impoundment will offgas (become a vapor in air) its organic compounds into the air. This becomes an air pollution problem, and the organic compounds are now termed Hazardous Air Pollutants (HAP’s). Additionally, separators, condensers, cryo plants and compressors can leak causing these volatile organic compounds to enter air. Incomplete combustion in flaring also adds VOC’s to air.

Part II: How volatile organic compounds act as precursor chemicals for the formation of ozone when combined with nitrogen oxides and carbon monoxide

Exposure to ground level ozone has been linked in many scientific studies to:

  • airway irritation, coughing, and pain when taking a deep breath,
  • wheezing and breathing difficulties during exercise or outdoor activities,
  • inflammation, aggravation of asthma and increased susceptibility to respiratory illnesses like pneumonia and bronchitis, and
  • permanent lung damage with repeated high exposures.

Ground level ozone also interferes with the ability of sensitive plants to produce and store food, making them more susceptible to certain diseases, insects, other pollutants, competition and harsh weather. It damages the leaves of trees and other plants, and reduces forest growth and crop yields, potentially impacting species diversity in ecosystems (EPA, 2008).

The best explanation for formation of ozone that I know of is contained in the 2008 EPA Air Quality Criteria for Ozone and Related Photochemical Oxidants (The entire 3 part EPA document is attached after this article). Ozone is a secondary pollutant that is formed in polluted areas by atmospheric reactions involving two main types of precursor pollutants volatile organic compounds (VOC’s) and nitrogen oxides (NOx). Carbon monoxide (CO) from incomplete combustion of fuels is also an important precursor for ozone formation. The formation of ozone and other oxidation products (like peroxyacyl nitrates and hydrogen peroxide), including oxidation products of the precursor chemicals, is a an extremely complex reaction that depends on the intensity and wavelength of sunlight, atmospheric mixing and interactions with cloud and other aerosol particulates, the concentrations of the VOC’s and NOx in the air, and the rates of all the chemical reactions. The EPA figure below shows all the possible reaction pathways and products that might be formed in both the troposphere (the lowest major layer, extending from the earth’s surface to about 8 km above polar regions and about 16 km above tropical regions) and the stratosphere (that is from the top of the troposphere to about 50 km above the earth’s surface). What happens in the lowest sublayer of the troposphere known as the planetary boundary layer (PBL) is most important for formation of ground level ozone and other reactive species that can cause health effects and is most strongly affected by surface conditions.
VOC refers to all carbon-containing gas-phase compounds in the atmosphere, both biogenic and anthropogenic” (biological and manmade) “in origin, excluding CO and CO2. Classes of organic compounds important for the photochemical formation of O3 include alkanes, alkenes, aromatic hydrocarbons, carbonyl compounds (e.g., aldehydes and ketones), alcohols, organic peroxides, and halogenated organic compounds (e.g., alkyl halides) Remember these are given off into air from produced water and flowback water at shale gas sites. This array of compounds encompasses a wide range of chemical properties and lifetimes; isoprene has an atmospheric lifetime of approximately an hour, whereas methane has an atmospheric lifetime of about a decade” (EPA, 2008). So the majority of ground level ozone is formed when ozone precursors NOx, CO, and VOC’s react in the atmosphere in the presence of sunlight. We have established that these VOC’s can come from volatilization of organic compounds from frac ponds-condensers and other gas processing equipment and compressor-transmission operation. Motor vehicle exhaust, emissions from coal powered electrical generation stations, industrial emissions and release of chemical solvents all put these precursor ozone producing chemicals into the air.

These precursors chemicals most often originate in urban areas, but winds can carry NOx hundreds of kilometers, causing ozone formation to occur in less populated regions as well. Methane, a VOC whose atmospheric concentration has increased tremendously during the last century, contributes to ozone formation but on a global scale rather than in local or regional photochemical smog episodes. In situations where this exclusion of methane from the VOC group of substances is not obvious, the term Non-Methane VOC (NMVOC) is often used. (EPA, 2008)

Now let’s examine the specific case of ozone and precursor chemicals for ozone as they exist over the Marcellus shale area without the addition of VOC’s from shale gas operations and the addition of diesel exhaust that also accompanies this process (from the thousands of truck trips to deliver water, chemicals, equipment, and sand and remove equipment and contaminated fluids – conservatively 1000 trips per well – thus over a year when 2000 wells are drilled there would be 2,000,000 truck trips). The maps that we are going to show were developed for the Pittsburgh Regional Environmental Threat Analysis (PRETA), in progress now (check back to in mid-September 2010 to visualize data on VOC’s, ozone, sulfur dioxide, nitrogen oxides, particulates [PM 10 and PM 2,5], carbon monoxide and other air contaminants across the four state region of Ohio, Pennsylvania, Maryland and West Virginia- these data and the maps presented below represent air contaminant means of the second highest 8-hour daily maximum values from 1998 -2008).

Map 1, 8 Hour Ozone Designation Areas shows that ozone levels in a 7 county area of Southwest PA are in ozone non-attainment right now—before the addition of new Marcellus Shale gas extraction sources. This area is one of the epicenters in PA of Marcellus Shale gas extraction.
Map 2, NO2 Levels 1998-2008 over 4 state region shows existing NO2 levels when monitoring station data are averaged and smoothed.

Map 3, NO2 Emissions in Tons for 2002 presents facilities releasing NO2 over the 4 state study area and an estimate of their NO2 emissions per tonnage category. Remember NO2 is a precursor gas for formation of ozone; areas downwind of these sites will thus have increased reactant for the formation of ozone. VOC’s from shale gas extraction activities may react with NO2 from these sources.