Last Updated on 2026-11-07
The McCully Gas Field in New Brunswick was discovered in 2000 and has been used for natural gas production since 2003. The field is within the Carboniferous Maritime Basin, which also contains significant potash deposits. Hydrofracturing (fracking) has been used to release natural gas from underground reservoirs. Unlike US hydrofracturing, where large quantities of pressurized water are injected and used to fracture sediments and release gas, compressed propane (LPG) is now used to provide pressure for fracturing in the McCully Field. The use of compressed propane (LPG) is referred to as ‘waterless fracturing‘. It is combined with a gelling agent and pumped into the well to create pressure that results in fracturing and release of natural gas. Propane gas can be recaptured from the well as it returns to gas form. Because it reverts to gas, the propane does not contain radioactive materials, brine or other contaminating materials as does water retrieved from water-based fracturing. Avoiding the use of large quantities of water greatly reduces the amount of water that needs to be hauled to water treatment facilities for recycling. This Canadian technology has been in use since about 2008.
Methane is the largest component of natural gas; other hydrocarbon gases, such as ethane and propane, are generally removed from natural gas during the purification process. Because it is a potent greenhouse-gas, methane releases into the atmosphere have long been a concern. More recently, methane contamination of groundwater used for drinking has become an issue, due to the potential of hydraulic fracturing technologies that allow methane to escape from deep reserves and potentially mix with groundwater reservoirs used for drinking water. There are other naturally-occurring gas hydrocarbons (such as ethane or propane) and potential contaminants (naturally occurring or added/released during hydrofracturing operations or gas processing) that are also of concern. Some of these (e.g. benzene) are suspected carcinogens. These may impact both air and water quality. A review of New Brunswick’s shale gas resource can be found here. See here for a summary of peer-reviewed science on the environmental and health impacts of shale gas
There is limited information available on environmental impacts of fracturing technology in the McCully Field. Here I review some of the information that is available – two conference presentations on water quality and a federal/provincial study on air quality. These are not peer-reviewed science journal articles, but they do contain useful information.
- Contamination of groundwater by methane and other gases.
Al, T.A., Leblanc, J., and Phillips, S. 2013. A study of Groundwater Quality from Domestic Wells in the Sussex and Elgin Regtion, New Brunswick: with Comparison to Deep Formation Water and Gas from the McCully Gas Field.;Geological Survey of Canada, Open File 7449, 40p. doi:10.4095/292762
http://ftp2.cits.rncan.gc.ca/pub/geott/ess_pubs/292/292762/of_7449.pdf
(Abstract): The exploration for shale gas in Canada has led to the identification of a huge volume of in-place and marketable natural gas with the potential of supplying clean burning fuel for many decades. However, some controversies exist on the technique used to unlock these new riches; that is hydraulic fracturing from high-pressure injection of slickwater, a mixture of water, chemicals and proppants (sand) in order to create and keep open small fractures in the target shale.
The Carboniferous Frederick Brook shale and the overlying Hiram Brook sandstone in southern New Brunswick are identified as promising sources for shale gas. Preliminary evaluation of in-place resources by one operator in the Moncton sub-basin suggests 67 Tcf of natural gas in their acreage. At the McCully gas field, there is production from one vertical well in the Frederick Brook shale but most of the production is from tight sandstone of the Hiram Brook Member. Initial exploration specific to shale gas has led to high expectations but inconclusive results. In the same period, societal concerns about the risk of groundwater contamination from shale gas exploration activities have increased significantly in New Brunswick. The Geological Survey of Canada, in collaboration with eastern Canada provincial stakeholders has initiated a four-year research project (2011-2015) designed to evaluate the potential of natural connectivity between the deep-seated shales and the shallow groundwater.
In 2012-2013, the Department of Earth Sciences at the University of New Brunswick carried out a sampling program of 26 water wells from the area around the McCully gas field near Sussex; the operator of the McCully gas field provided gas and brine samples for chemical and isotopic comparison. This gas field has experienced multiple hydraulic fracturing events in vertical wells for the development of the tight sandstone gas reservoir from 2000 to 2008. The research program consisted of field measurements (pH, redox and alkalinity) as well as groundwater sampling for isotope analyses (18O and 2H) and inorganic chemistry, measurements of dissolved hydrocarbons (methane, ethane and propane) and isotope analyses (13C and 2H) of dissolved methane. Methane from the gas field was isotopically characterized as well as the inorganic chemistry of the brine.
The McCully brine has concentrations of Na, Cl and Br that are hundreds of times higher than that of shallow groundwater. Concentrations of K, Ca, Mg and SO4 are also higher than those of shallow groundwater; from its chemistry, the brine is likely derived from seawater and comparison with shallow groundwater does not indicate mixing.
Gas produced at McCully is methane (91 – 94%) with ethane (2 – 6%) and propane (0.1 – 1%). Isotopic analyses of the methane suggest a thermogenic origin. No ethane or propane was measured in the groundwater and methane was detected in 3 domestic wells. Concentrations are very low (0.01, 0.11 and 1.17 mg/L); the 3 samples are outside the McCully gas field area. Two of these samples had enough methane for 2 isotopic analyses, one suggestive of a thermogenic origin and the other is enriched in 2H that could be related to oxidation of methane.
Comment (by NBdatapoints): 3 of 28 (or 3 of 25, depending upon whether or not you count the duplicate samples) tested samples of water had detectable methane. That’s about 12% of samples, and methane was found only in samples taken outside the gas field area. Ethane and propane were not detected. This area (McCully Field) is where gas exploration and hydraulic fracturing operations have taken place for several years. The results suggest that methane contamination of groundwater by fracking operations in the McCully Field is uncommon.
- Domestic well water quality in shale gas regions of New Brunswick
Loomer, D.B., MacQaurrie, K.T., Connor, D., Bragdon, I., Leblanc, J.F., and Lewey, T. 2014. A Baseline Assessment of Domestic Well Water Quality in Potential Shale Gas Regions of New Brunswick: Initial Results for Dissolved Gases.
Abstract of presentation made at the Exploration, Mining and Petroleum New Brunswick Conference 2014, November 2-4, Fredericton NB.
http://www2.gnb.ca/content/dam/gnb/Departments/en/pdf/Conference/EMP_2014_Agenda.pdf
(Abstract): The production of oil and natural gas is an activity that generates public and regulatory issues concerning fresh water resources. These issues are relevant to the protection of water supplies for domestic, municipal, and industrial uses, and to maintaining the ecological health of surface water systems such as rivers and lakes. The recent exploration activities for natural gas in New Brunswick have highlighted the keen interest and concern over potential impacts to groundwater.
The collection of scientifically-defensible baseline groundwater quality data is crucial because it can provide the public, regulators, and industry with a better understanding of groundwater quality conditions. Furthermore, baseline data can assist in identifying water quality consequences, if any, of industrial activities such as shale gas production. Such regional groundwater quality studies can also assist in determining if hydrogeological conditions (e.g. aquifer confinement) or water well construction are important factors in controlling the occurrence of dissolved gasses such as methane in well water.
From May to September 2014, private water wells were sampled in two areas in southern New Brunswick: northeastern Kent County, and the area between Havelock, Sussex and Elgin. Along with field parameters such as pH, dissolved oxygen and oxidation/reduction potential, water samples were collected for inorganic ions, dissolved gases (methane, ethane and propane), and stable isotopes of water and methane. The results for dissolved gas concentrations will be the focus of this presentation.
To date (September 2014), 149 wells have been sampled in the Sussex study area. Methane has been detected in 49% of the sampled wells. Of the wells with detectable methane, 84% had methane concentrations between 0.001 and 1.0 mg/L. Only 4% of the wells with detectable methane had concentrations greater than 10 mg/L. Ethane was detected in 8% of the sampled wells with concentrations ranging from 0.001 to 1.441 mg/L. Propane was detected above the blank-corrected detection limit of 0.002 mg/L in 2 of the samples.
In the Kent County study area, 101 wells have been sampled and methane was detected in 69% of the wells. Of the wells with detectable methane, 97% had methane concentrations between 0.001 and 1.0 mg/L and no wells had concentrations greater than 10 mg/L. Ethane and propane concentrations were at or below the detection limit (0.001 mg/L) for all samples in the Kent County area.
The results will be briefly compared to findings from similar studies in other areas.
Comment (by NBdatapoints): These baseline data suggest that naturally-occurring methane contamination of groundwater is widespread in some parts of New Brunswick. Concentrations found were low for the most part. Ethane and propane were detected in a few samples. Generally, methane in groundwater is not considered to be a health hazard if ingested, but odours from methane can be objectionable.
- Air quality monitoring around shale gas sites in New Brunswick
In 2012, the Canadian federal government launched a study, in collaboration with the provincial government of New Brunswick, aimed at assessing potential impacts of hydrofracturing and shale gas extraction on air quality. Monitoring was done in the Kennebecasis valley in the McCully gas field area. The McCully field, discovered in 2000, was the first location in Canada where hydrofracturing was used to recover natural gas. Gas extraction began there in 2003. The air quality monitoring study began in 2013 and data collection for this preliminary study was completed in 2015. Results and conclusions are summarized here. Quotations below come directly from the reports, I have bolded some of the quoted text to emphasize certain conclusions.
The air quality monitoring report consists of four parts:
- Phase I (2014) was designed to monitor air quality that could be expected prior to development of shale gas reserves. The resulting Report 01 provides some preliminary baseline data and also serves as an introduction to the overall project.
- Phase II (2015) includes results from monitoring of the baseline, processing and closed sites. Report 02 includes results from Phases I, III, and IV
- Phase III (2016) was designed to monitor air quality at a shale gas production site during a fracking operation, which was conducted at a shale gas well in Penobsquis, New Brunswick. Report 03
- Phase IV was designed to monitor emissions from a closed (capped) natural gas well. Report 02
- Synopsis. This is a summary of ‘all the monitoring at all stages of shale gas development. It provides general conclusions for a non-technical audience. It does not include the detailed information, which is in the three previous reports’.
Report 01:
This report provides locations and descriptions of sampling sites (Kennebecasis River valley, near Penobsquis) for all phases of the study. The Phase I (baseline, or pre-development of a shale resource) sampling site was near Apohaqui, southwest of Sussex within the Kennebecasis River valley, and is upwind of Phase III and Phase IV) and also upwind of natural gas wells and two gas plants currently operating in Penobsquis. The conclusions of the preliminary samplings were ‘Preliminary analyses of these data and comparisons with historical air quality trends across the southern part of the province of New Brunswick (including Fredericton, Saint John and Moncton) show that the concentrations of air pollutants at the baseline site are similar to or lower than those at other provincial monitoring sites (rural and/or urban). The wind data also indicated that no significant sources of pollution, especially oil and gas activities, were located upwind of the site. As such, it would appear that the baseline data will provide an appropriate data set against which to compare air quality data collected during other phases of the study.’
Report 02:
Report 02 includes a complete data analysis for the baseline site in Apohaqui (Phase I), from air samples collected near an existing gas processing site (Phase III), and air quality near from two closed wells (Phase IV). See the report for collection details and a list of pollutants that were measured.
Phase I: ‘Phase I data provided information on regional pollutant levels that can be considered as “normal” (i.e., baseline) for the area in which the study sites were located. The pollutants that were monitored included criteria air contaminants, such as carbon monoxide, nitrogen oxides, ozone and particulate matter, as well as non-criteria air pollutants and air toxics, such as metals and polycyclic aromatic compounds. For the criteria pollutants, the results showed that pollutant levels were similar to, or lower than average pollutant levels reported at air monitoring stations across New Brunswick. Pollutant levels were notably lower than those recorded in the larger urban centres of New Brunswick – that is, Fredericton, Moncton and Saint John. Although comparisons were not possible for all pollutants, the absence of significant emission sources of pollutants upwind of the Phase I site suggested that the levels observed were not significantly influenced by local anthropogenic sources. Thus, the site allowed the collection of regionally representative air pollutant data that could be used to assess the influence of local sources on pollutant levels in the region of Sussex, New Brunswick.’
Phase III: ‘Phase III of the study involved the collection of data around an existing natural gas treatment facility in Penobsquis, New Brunswick. Data collected during Phase III indicated that emissions from the gas treatment facility had a measurable but limited influence on air pollutant concentrations, notably for volatile organic compounds (VOCs). Higher concentrations were reported for some VOCs at sampling locations downwind from the facility compared with sampling locations positioned upwind. Several VOCs could be associated with natural gas operations, such as butane, hexane, pentane and propane. Nonetheless, the results suggested that measured concentrations were below levels considered as being a risk to human health. For example, they were lower than air quality standards that have been adopted by some Canadian jurisdictions and similar to, or lower than levels measured across New Brunswick.’ According to the report, pollutant concentrations fell to baseline levels a few hundred metres from the plant location.
Phase IV: ‘Samples collected at a site with two suspended natural gas wells (Phase IV) showed low concentrations of VOCs and methane. Some compounds were measured at higher levels compared with Phase I and Phase III, notably decane and undecane. Additional information was considered necessary to identify potential sources and causes of these higher concentrations. Nonetheless, these compounds were not measured at concentrations that are of concern to human health.’
Overall, differences in air quality between the baseline, gas processing sites and closed wells were small, and measured concentrations were generally below those that would be expected to adversely affect human health. But, ‘the monitoring for this study was based around a single gas treatment facility and did not evaluate the potential cumulative impacts of multiple gas plants that would be necessary under a scenario of expanding natural gas production in Kings County, New Brunswick.’
Report 2 also referred to additional sources of pollutants that might have affected results. ‘For example, as part of the Canada Day celebrations, the Town of Sussex organized fireworks at approximately 22h00 on July 1, 2013.30 The time of the fireworks concurred with a spike in PM2.5 concentrations (30–40 μg/m3) over several hours at the gas plant, which was located only a few kilometres from Sussex (see Figure B4 in Appendix B). Based on wind data for July 1, 2013, the wind was blowing from the southwest – that is, from Sussex towards the gas treatment plant – and it is likely that particulates from the fireworks were transported and affected the measurements. The winds did shift on July 2, and blew from the northeast, when PM2.5 decreased to typical levels (10–15 μg/m3).
An air quality advisory was also issued by the Government of New Brunswick on July 1, 2013.31 The poor air quality resulted from the transport of smoke from forest fires in northern Quebec. Although the smoke was projected to affect air quality in northern New Brunswick, air pollutant levels in Sussex may have been influenced via long-range transport of forest fire emissions. Unfortunately, PM2.5 filter samples for the analysis of biomass burning markers (e.g., levoglucosan) were not scheduled for July 1, 2013, at the Phase I or Phase III sites.’
Report 03:
The main focus of this report was to report on air pollutants released prior to, during, and after a hydrofracturing event in the McCully field, near Penobsquis. The wells in this area were fracked using propane, not water injection (unlike the case for most of the US sites discussed here).
‘The main objective of the Phase II air quality monitoring was to capture a hydraulic fracturing event during the completion of well E-67B; this occurred in September 2014. Air quality data were collected from June 20, 2014 until March 31, 2015 – that is, several weeks prior to major well activities, during hydraulic fracturing, and several months following well completion’
‘Overall, ambient air pollutant levels were generally low or below air quality guidelines during Phase II. It is important to point out that Phase II covered and focused on a single hydraulic fracturing event. As such, it is not necessarily indicative of the air quality impacts of a fully developing or developed unconventional gas play. An active play would likely involve the concurrent development of several well pads, concurrent well completions, increased road traffic and off-road activity, and increased flaring, for example. Although individual well pads or natural gas facilities, based on the findings from the current study, may not have a considerable impact on air quality, the cumulative impacts on local or regional pollutants could be greater. For example, a multitude of dispersed well pads (i.e. local sources) could eventually have a measurable impact on regional air quality, for pollutants such as O3 or PM2.5. More local and regional data is necessary to characterise or predict the air quality impacts associated with air pollutant emissions from multiple well pads or natural gas facilities.’
In other words, the pollutants detected in the air around the fracked site were not of concern in regards to human health, but multiple fracking operations taking place at the same or similar times might be of more concern:
‘Overall, the analyses show that pollutant concentrations during Phase II were lower than ambient air quality standards adopted in New Brunswick or in other Canadian jurisdictions. Therefore, the results from the current study suggest that air pollutants did not reach levels that are of concern to environmental and human health, or that would trigger mitigation measures to improve air quality. However, measurable air quality impacts were observed and, importantly, the study design did not account for potential cumulative impacts from the development of multiple wells in the area. Further, air quality standards were not reviewed or assessed during this study. The rationale or approach used to define air quality standards may vary among pollutants and jurisdictions, depending on the endpoint or the intent of the standard. Thus, some air quality standards may not be the most relevant for an assessment of population health impacts from air pollution’
‘Based on the study findings, comprehensive air monitoring is recommended near well pads in order to capture air pollutant releases from unconventional gas development and to accurately assess the air quality impacts. Owing to the intermittent and frequent releases of air pollutants during the different stages of well development, the monitoring period should include periods prior to, during and following drilling and well completion stages. Continuous monitors should also be selected, if feasible, along with integrated samples (e.g., 24 h samples, weekly samples), as appropriate for the targeted air pollutants. The monitoring approach should target NOx, PAH, PM2.5 and VOC concentrations, if possible. Samples and measurements should also be collected using validated methods for reliable comparisons with air quality standards and data from regional or national surveillance programs, such as NAPS in Canada.’
Synopsis:
Main conclusions: ‘Activities conducted on the well pad during Production had a measurable impact on air pollutant levels, especially at downwind locations, but the impact was brief and air pollutant levels remained below current ambient air quality standards or provincial governments in Canada.7 Moreover, average air pollutant levels during production were similar to those measured at Baseline and to those measured at monitoring sites across New Brunswick (i.e. NAPS monitoring stations). The increases in pollutant levels corresponded to periods of intensive well operations, such as drilling, hydraulic fracturing, snubbing, venting and flow testing. A variety of operations before, during and after a hydraulic fracturing event may have influenced air pollutant levels; in some cases more than the hydraulic fracturing event itself. These included, for example, drilling activities, well snubbing and gas flow testing (refer to Report 03).’
‘At the Processing site, concentrations of criteria air contaminants such as CO, O3 and PM2.5 were comparable to Baseline conditions. However, the data indicated that the natural gas treatment facility had an influence on the ambient level of several VOCs. These included alkane species generally associated with oil and gas operations, such as butane, decane, heptanes, hexane, octane, pentane and propane. Nonetheless, air pollutant concentrations remained below air quality standards that have been adopted by Canadian jurisdictions and were similar to or lower than levels at the Baseline site or at NAPS monitoring sites across New Brunswick. Overall, the results from the Processing site monitoring indicated that emissions from the gas treatment facility had a measurable, but limited influence on air VOC levels.’
‘Ambient concentrations of VOCs and methane were generally low during the monitoring at the Closure site. Criteria air contaminants were not measured during this phase. The measured concentrations for several VOCs associated with the use, manufacture or disposal or petroleum products were higher than those at Baseline, but were all below air quality standards that have been adopted by Canadian jurisdictions. Based on the available information, it was not possible to identify the exact origin(s) of the measured VOCs (e.g., inadvertent spills during previous activities at this site including drilling, hydraulic fracturing or site preparation). Many of these VOCs are not necessarily linked to natural gas production, although they may be indicators of petroleum fuels, such as diesel or kerosene. Hence, the Closure results suggested that fugitive VOC emissions were occurring on or near the well pad, but the results are inconclusive.’
‘Overall, pollutant levels during Production, as well as other phases, were lower than ambient air quality standards adopted in New Brunswick or in other Canadian jurisdictions. Therefore, the results from the current study suggest that air pollutants did not reach levels that are of concern to environmental and human health, or that would trigger mitigation measures to improve air quality. Based on the study findings, comprehensive air monitoring is recommended near well pads in order to capture air pollutant releases from unconventional oil and gas development and accurately assess the air quality impacts. Owing to the intermittent and frequent releases of air pollutants during the different stages of well development, the monitoring period should include periods prior to, during and following drilling and well completion stages. Continuous monitors should also be employed, if feasible, along with integrated samples (e.g., 24 h samples, weekly samples), as appropriate for the targeted air pollutants.’
Comment (by NBdatapoints): The data presented in these reports on air quality indicate that there are limited impacts on that from the shale gas sites that were the subject of testing. It remains to be seen whether a more concentrated industry would have any significant impacts on air or water quality. Clearly, monitoring sites both near shale gas extraction sites and residential areas near them would be helpful in assessing any negative impacts resulting from an expansion of the industry. In addition, water samples at the extraction sites and from groundwater wells at various distances from those sites should be part of the monitoring process. New Brunswick has an opportunity to exploit a valuable resource with appropriate monitoring. What is the status of regulation in New Brunswick? Here are the current regulations (released in 2013).
Related pages:
What the peer-reviewed science says about shale gas