Background


Situation of Natural Gases in BC

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Natural gas is a mixture of hydrocarbon gases, predominated by methane, typically includes higher hydrocarbons (e.g., ethane through pentane) and frequently non-hydrocarbons, such as carbon dioxide, nitrogen, hydrogen, noble gases and hydrogen sulfide. Natural gas is globally ubiquitous, but particularly important in British Columbia from economic and environmental perspectives.

B.C.’s history of petroleum dates back over 90 years since the 1920’s. The first commercial production of natural gas in 1948 (Pouce Coupe) delivered gas to Dawson Creek (Figure 1). This was followed by the natural gas discovery in 1956 at Clarke Lake in the Fort Nelson region.

Today, the development centers upon B.C.’s reserves of conventional and unconventional natural gas located under the edge of the Western Canada Sedimentary Basin (WCSB) in the province’s northeast (Figure 1). The unconventional gas types present in B.C include: Tight, Shale and Coalbed gas (CBG or coalbed methane, CBM).

Figure 1. Map of B.C. plays in the Western Canada
Sedimentary Basin hydrocarbon basins
(BC OGC 2013. Area-based Analysis: Overview April 2013).

In B.C., the Montney (Ft. St. John/Dawson Creek), Horn River and Liard Basins and the Cordova Embayment (Ft. Nelson), shown in Figure 2, are among the largest shale-gas deposits in North America, with an estimated resource of approximately 11,000 bcm (billion cubic metre, NEB et al., 2013). These deposits are part of the rich, interprovincial oil and gas reserves of the WCSB connecting B.C. and Alberta.

For example, the 130,000 km2, 100 – 300 m thick Triassic Montney Formation yields oil (179 mcm), natural gas liquids (2,300 mcm NGLs) and natural gas (> 12,000 bcm) (NEB, 2015). Although the deeper, over-pressured plays dominate the unconventional development in B.C. Montney Fm (mid-point depth ~ 1750 m), shallower, underpressured production, similar to Alberta (also Doig Fm), remain of interest. In 2013, the Montney comprised 51 % of gas production in NE B.C. (OGC, 2014).

Natural gas reserve and marketable resource estimates for the Horn River Basin are approximately 314 and 2,000 bcm, respectively, and the production of 4.25 bcm in 2013 accounted for about 13 % of total production in the province. The Jean Marie and Cadomin make up 4.6 and 3 % of NE B.C. gas production, respectively (OGC, 2014).

Note: NGLs are defined as ethane, propane, butane, pentane, and heavier hydrocarbons that are produced in the gas stream out of a well.

Figure 2. Map of northeast B.C. unconventional
hydrocarbon plays (BC OGC, 2014. Horn River Basin
Unconventional Shale Gas Play Atlas).

Currently in B.C., our known natural gas reserves are approximately 1,200 bcm with an annual production of around 39.5 bcm from over 7,700 producing wells (610 drilled in 2014). (Sources: BC OGC 2013, 2014, CAPP 2011).

B.C. has several other sedimentary basins, which have had more limited exploration, including the Bowser, Whitehorse, Nechako, Fernie, Queen Charlotte, Winona and Tofino Basins (Figure 3). These contain oil and/or both conventional and unconventional gas. The latter includes coalbed gas found in essentially every coalfield throughout the province. The major estimated reserves include the Peace River (northeast), Klappan and Groundhog (north Netchako basin), Elk Valley and Crowsnest (southeast corner), Hat Creek (central interior), and Comox and Nanaimo (Vancouver Island). Exploratory wells in the Peace River and Elk Valley coalfields are assessing the CBG.

Figure 3. Map of B.C.’s active and prospective
hydrocarbon basins (BC Ministry of Energy and Mines).

Application and Value

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Certainly, the natural gas industry in northeast British Columbia, particularly in the unconventional market, is experiencing a period of sustained growth due to several reasons, including technological (e.g., advanced directional drilling, improved hydraulic fracturing), economic (decline in global oil reserves) and social (lower greenhouse gas emissions and cleaner extraction, transport and use). The rich resources of B.C. natural gas are generating the opportunities for an emerging LNG industry on B.C.’s west coast.

This intensive rise in the exploration and production of natural gas in B.C. brings a range of both opportunities and challenges that can be improved by this BC Natural Gas Atlas. Molecular and isotope signature of natural gases provide important information for exploration activities (e.g., Whiticar, 1994). For example, natural gas signatures can elucidate the kerogen types and maturity of the source rocks that generated the gas (see Appendix 1). Additionally, in unconventional plays, these gas geochemical signatures can help identify spatial variations in productivity, e.g., due to facies changes. When embedded in a Petroleum System Model, the gas data can provide source rock calibration and can identify charge histories. Overall this can substantially reduce exploration risk.

Due to subtle changes in molecular and isotope signatures between and across units (e.g., permeability contrasts) the gas geochemistry assists in the recognition of migration, mixing, segregation and compartmentalization within petroleum systems and the distribution of natural gas liquids. With appropriate sampling density and control gas geochemistry can add insight on the effectiveness of structural and stratigraphic seals and the impact on basin evolution of traps and seal integrity. It can also address questions of secondary alteration, such as water and gas washing and biodegradation.

During production activities, natural gas signatures offer benefits to the operator, which potentially allow them to optimize field operations and gas production. Understanding the compositional variations and quality of the gas within plays can optimize where specific gas-types and production performance can be anticipated.

Wells now utilize state-of-the-art drilling, completion methods and production equipment and techniques. However, there are still concerns that compromised surface casing cements in active well bores, e.g., from pressure cycling during hydraulic fracturing, could be allow the migration of gases to the surface and resulting in fugitive gas releases into the atmosphere. There are also additional concerns of fugitive gases from abandoned well bores. The capability of not only identifying wells that are leaking gas sources, but characterizing the source of the gas has many benefits. In the case of a leaking wellbore, an operator can lower remediation costs by having a high level of certainty as to the gas source, thereby allowing the operator to quickly and efficiently plan remediation of leaking wellbore. This same methodology could be used to remediate old abandoned wellbores – the methodology would allow the service company to pinpoint the horizon(s) leaking, thereby aid intervention strategies to reduce fugitive gas emissions.

Detecting natural gas emissions from natural gas development is critical for responsible development of the resource, and for population health and wellness of communities. Differentiation between microbial and different thermogenic sources of natural gas will be a critical, novel enhancement to the hydrocarbon fugitive emission air-monitoring network. This can work in concert with the BC Ministry of Environment Northeast Air Monitoring Project (Science and Community Environmental Knowledge, SCEK, Fund), a partnership between the B.C. Government, OGC and the oil and gas industry.

This project interfaces and participates in two existing fugitive emission and water quality programs in NE B.C., namely:

  1. OGC/UBC ‘Fugitive Gas Emission Characterization Study’
  2. OGC/BCMFLNRO/BCMoE/SFU ‘Northeast BC Aquifer Characterization Study’.

In the OGC/UBC study 15 well pads were selected near Fort St. John and Dawson Creek, where most of the unconventional gas development focuses on the upper and lower Triassic Montney Fm (Figure 4). Some wells were drilled to target the overlying Charlie Lake, Halfway and Doig Fm, and the lower Cretaceous Fm. Discussion are ongoing to expand the OGC/UBC study into the Devonian Muskwa, Otter Park and Evie Members of the Horn River Region (Figures 2 and 5).

Figure 4. Stratigraphic cross section Ft. St John region of NEBC (MEM).

Figure 5. Stratigraphic cross section of Horn River and Liard Basins. BC OGC, 2014.

Fingerprinting of Natural Gases

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A distinct and diagnostic natural gas compositional signature theoretically can be obtained from a combination of:

  1. Molecular abundances – CH4, C2H6, C3H8, iC4H10, nC4H10, CO2, N2, H2S, etc.

  2. Stable isotope ratios – δ13CH4, Cδ2H4, δ13C2H6, δ13C3H8, δ13 iC4H10, δ13nC4H10, δ 13CO2, etc.

Recent studies detailed in the Results section show that there is no clearly defined “fingerprint” in NEBC – it is an interpretative result with many gases looking fairly similar to each other. The Geochemistry page shows the complexity in doing Gas Characterization plus the many factors and tools using in that interpretation.

Natural gas signatures in fugitive emissions to aquifers and groundwaters

From an environmental assessment perspective, the BC-NGA will establish a suite of gas fingerprints that can address concerns of natural and anthropogenically-induced seepage or introduction of natural gases into aquifers and surface groundwaters. This aspect of the project is planned to be conducted in conjunction with the two existing joint projects:

  1. Northeast BC Aquifer Characterization Study (NBCACS) BC Oil and Gas Commission (OGC), BC Ministries of Forests, Lands and Natural Resource Operations (BC MFLNRO), Environment (BC MoE), and Simon Fraser University (SFU) contacts: C. van Geloven D. Wilford and D. Kirste. During the next years, NE B.C. waters will be routinely sampled from over 100 water and monitor wells and from other exposures to determine their chemical characteristics (inorganic and organic). Our part in this project will be to analyse the dissolved gas molecular and isotope compositions in the waters and provide interpretations on the sources of the gases, i.e., allochthonous vs. autochthonous, or microbial vs. thermogenic, etc. The detailed BC-NGA signature inventory will provide the gas type end-members for attribution of sources.
  2. Fugitive Emission Characterization Study BC Oil and Gas Commission (OGC), and University of British Columbia (UBC) contacts: K Parsonage, U. Mayer. Similar to the above NBCACS, this study will interpret the origin of the gases, i.e., allochthonous vs. autochthonous, or microbial vs. thermogenic, etc. In the case of thermogenic gases the project will establish, using the detailed BC-NGA signature inventory, the links of shallow gas occurrences with potential sources in the subsurface. During the project, we are participating in analyzing gas samples collected from over 25 oil and gas well sites in NE. B.C. Our part in this project is to analyse the stable carbon and hydrogen isotope compositions of:
    1. Free gases fluxing out of the soil at well sites and
    2. Dissolved gases in the waters in the wellbores.

References

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BC Oil and Gas Commission 2012 Montney Formation Play Atlas NEBC. British Columbia Oil and Gas Commission URL < https://www.bcogc.ca/montney-formation-play-atlas-neb > [July 2018]

BC Oil and Gas Commission 2013 Hydrocarbon and By-Product Reserves in British Columbia 2015-02-20

BC Oil and Gas Commission 2013. Area-based Analysis: Overview 15 p.

BC Oil and Gas Commission 2014 Horn River Basin Unconventional Shale Gas Play Atlas. British Columbia Oil and Gas Commission URL < https://www.bcogc.ca/horn-river-basin-play-atlas > [July 2018]

BC Oil and Gas Commission 2015a Isotopic analysis and submission guideline, BC Oil and Gas Commission URL < https://www.bcogc.ca/isotopic-analysis-and-submission-guideline > [October 2016].

BC Oil and Gas Commission 2015b Section 34: tests, analyses, surveys and logs; in Oil and Gas Activities Act: BC Oil and Gas Commission Drilling and Production Regulation, B.C. Reg. 165/2015, URL < http://www.bclaws.ca/civix/document/id/loo97/loo97/282_2010#section34 > [November 2016]

BC Oil and Gas Commission 2016 INDB 2016-07 submission of isotopic gas analyses, BC Oil and Gas Commission URL < https://www.bcogc.ca/indb-2016-07-submission-isotopic-gas-analyses > [October 2016].

BC Oil and Gas Commission 2018 BC Oil and Gas Commission 2016/17 Annual Service Plan Report. BC Oil and Gas Commission URL <https://www.bcogc.ca/node/14394/download > [July 2018]

Bernard, B.B., J.M. Brooks, and W.M. Sackett, 1978, Light hydrocarbons in recent Texas continental shelf and slope sediments: Journal of Geophysical Research, v. 83, p. 4053-4061.

Berner, U., 1989, Entwicklung und Anwendung empirischer Modelle für die Kohlenstoffisotopenvariationen in Mischungen thermogener Erdgase, Ph.D. dissertation, T.U. Clausthal, 160 p.

CAPP 2015. Canadian Association of Petroleum Producers' Statistical Handbook for Canada’s Upstream Petroleum Industry, Technical Report, 230 p.

Claypool, G.E., 1974, Anoxic diagenesis and bacterial methane production in deep sea sediments, Ph.D. Thesis, UCLA, 276 p.

ESRD 2015, Directive 035: Baseline Water Well Testing Requirement for Coalbed Methane Wells Completed Above the Base of Groundwater Protection. https://www.aer.ca/documents/directives/Directive035.pdf

Faber, E., and W. Stahl, 1984, Geochemical surface exploration for hydrocarbons in the North Sea: AAPG Bulletin, v. 68, p. 363-386.

Faber, E., 1987, Zur Isotopengeochemie gasförmiger Kohlenwasserstoffe: Erdöl Erdgas und Kohle, v. 103, p. 210-218.

Faber, E., W. Stahl, M.J. Whiticar, J. Lietz, and J.M. Brooks, 1990, Thermal hydrocarbons in Gulf Coast sediments: SEPM Gulf Coast Section (GCSEPM) Foundation 9th Annual Research Conference Proceedings Oct 1, 1990 p. 297-307.

Gerling, P., 1985, Isotopengeochemische Oberflächenprospektion Onshore: BGR Internal Report, No. 98576, 36 p.

Horvitz, L. 1982. Upward migration of hydrocarbons from gas and oil deposits, 183rd Am. Chem. Soc. Nat. Mtg., Las Vegas, Nevada, March 28-April 2.

Jenden, P.D., K.D. Newell, I.R. Kaplan, and W.L. Watney, 1988, Composition of stable isotope geochemistry of natural gases from Kansas, Midcontinent, USA: Chemical Geology, v. 71, p. 117-147.

MEM 2006a Conventional natural gas play atlas, part 1. BC Ministry of Energy and Mines Petroleum Geology Publication 2006-01, Oil & Gas Division, Resource Development & Geoscience Branch, URL < http://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/natural-gas-oil/petroleum-geoscience/oil-gas-reports/og_report_2006-1_nebc_atlas_part1.pdf > [October 2016].

MEM 2006b Conventional natural gas play atlas. BC Ministry of Energy and Mines Petroleum Geology Publication 2006-01, Oil & Gas Division, Resource Development & Geoscience Branch, URL < http://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/natural-gas-oil/petroleum-geoscience/oil-gas-reports/og_report_2006-1_nebc_atlas-2_part2.pdf > [October 2016].

MEM 2006c Conventional natural gas play atlas. BC Ministry of Energy and Mines Petroleum Geology Publication 2006-01, Oil & Gas Division, Resource Development & Geoscience Branch, URL < http://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/natural-gas-oil/petroleum-geoscience/oil-gas-reports/og_report_2006-1_nebc_atlas_part3.pdf > [October 2016].

MEM 2011 The Ultimate Potential for Unconventional Natural Gas in Northeastern British Columbia's Horn River Basin. National Energy Board and Ministry of Energy and Mines 2011-1. URL < https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/natural-gas-oil/petroleum-geoscience/oil-gas-reports/og_report2011-1.pdf > [October 2016]

MEM 2013 The Ultimate Potential for Unconventional Petroleum from the Montney Formation of British Columbia and Alberta. National Energy Board, BC Oil & Gas Commission, Alberta Energy Regulator, Ministry of Natural Gas Development 2013-3. URL < https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/natural-gas-oil/petroleum-geoscience/oil-gas-reports/og_report_2013-1_montney_assessment.pdf > [October 2016]

MEM 2015 Unconventional Natural Gas Assessment for the Cordova Embayment in Northeastern British Columbia. Ministry of Natural Gas Development and BC Oil & Gas Commission 2015-1. URL < https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/natural-gas-oil/petroleum-geoscience/oil-gas-reports/og_report_2015-1.pdf > [October 2016]

NEB 2013, The Ultimate Potential for Unconventional Petroleum from the Montney Formation of British Columbia and Alberta - Energy Briefing Note. https://www.neb-one.gc.ca/nrg/sttstc/ntrlgs/rprt/ltmtptntlmntnyfrmtn2013/ltmtptntlmntnyfrmtn2013-eng.pdf

NEB 2016 The Unconventional Gas Resources of Mississippian-Devonian Shales in the Liard Basin of British Columbia, the Northwest Territories, and Yukon - Energy Briefing Note. National Energy Board, Canada. ISBN 978-0-660-04668-6 https://www.neb-one.gc.ca/nrg/sttstc/ntrlgs/rprt/ltmtptntlbcnwtkn2016/index-eng.html

Oremland, R.S., M.J. Whiticar, F.E. Strohmaier, and R.P. Kiene, 1988, Bacterial ethane formation from reduced, ethylated sulfur compounds in anoxic sediments: Geochimica et Cosmochimica Acta, v. 52, p. 1895-1904.

Schoell, M. 1980 The hydrogen and carbon isotopic composition of methane from natural gases of various origins. Geochimica et Cosmochimica Acta 44 : 5 : 649-661 https://doi.org/10.1016/0016-7037(80)90155-6

Schumacher D. and M.A. Abrams (eds.), 1996. Hydrocarbon Migration and its Near-Surface Expression. AAPG Memoir 66, AAPG, Tulsa, 446p.

Schumacher D. and L.A. LeSchack (eds.), 2002. Surface Exploration Case Histories: Applications of Geochemistry, Magnetics, and Remote Sensing, AAPG Studies in Geology No. 48 and SEG Geophysical References Series No. 11 400p.

Stahl, W., 1973. Carbon isotope ratios of German natural gases in comparison with isotopic data of gaseous hydrocarbons from other parts of the World. in Tissot, B. and Bienner, F. eds. Advances in Organic Geochemistry. Pergamon, Oxford, pp. 453-462.

Stahl. W.. 1977. Carbon and nitrogen isotopes in hydrocarbon research and exploration. Chemical Geology 20 : 2 : 121-149 http://dx.doi.org/10.1016/0009-2541(77)90041-9

Stahl, W., and J. Koch, 1974, 13C/12C-Verhälltnis nordeutscher Erdgase – Reifemerkmal ihrer Muttersubstanzen: Erdöl und Kohle-Erdgas-Petrochemie, v. 27, p. 10.

Stahl, W., E. Faber and D.L. Kirksey, 1981. Near-surface evidence of migration of natural gas from deep reservoirs and source rocks, AAPG Bull 65: 1543-1550.

Whiticar, M.J. 1990 A Geochemical Perspective of Natural-Gas and Atmospheric Methane. Organic Geochemistry 16 : 1-3 : 531-547 http://dx.doi.org/10.1016/0146-6380(90)90068-B

Whiticar, M.J. 1994 Correlation of Natural Gases with Their Sources. In: Magoon, L.B. and Dow, W.G. eds The Petroleum System – from source to trap. AAPG Memoir 60. https://www.aapg.org/publications/special-publications/cds/details/articleid/3938/m60-cd-the-petroleum-system-from-source-to-trap

Whiticar, M.J. 1996 Stable isotope geochemistry of coals, humic kerogens and related natural gases. Int. J. Coal Geol. 32 : 1-4 : 191-215 http://dx.doi.org/10.1016/S0166-5162(96)00042-0

Whiticar, M.J. 1999 Carbon and hydrogen isotope systematics of bacterial formation and oxidation of methane. Chem. Geol. 161 : 1-3 : 291-314 http://dx.doi.org/10.1016/S0009-2541(99)00092-3

Whiticar, M.J. and Eek, M.K. 2001 Challenges of 13C/12C measurements by CF-IRMS of biogeochemical samples at sub-nanomolar levels in IAEA eds. New approaches for stable isotope ratio measurements. IAEA TECDOC-1247 pp.75-95 ISSN 1011–4289 https://www-pub.iaea.org/MTCD/Publications/PDF/te_1247_prn.pdf https://www-pub.iaea.org/books/IAEABooks/6293/New-Approaches-for-Stable-Isotope-Ratio-Measurements

Whiticar, M.J., and E. Faber, 1986. Methane oxidation in sediment and water column environments—isotope evidence: Organic Geochemistry, v. 10, p. 759-768.

Whiticar, M.J., Faber, E., Schoell, M. 1986 Biogenic methane formation in marine and freshwater environments: CO2 reduction vs. acetate fermentation-Isotope evidence. Geochemica et Cosmochimica Acta 50 : 693-709 http://dx.doi.org/10.1016/0016-7037(86)90346-7

Other references for publications

Evans, C. (2019): Molecular composition and isotope mapping of natural gas in the British Columbia Natural Gas Atlas; in Geoscience BC Summary of Activities 2018, Geoscience BC, Report 2019-1, p. 77–84 URL http://cdn.geosciencebc.com/pdf/SummaryofActivities2018/EW/2015-013_SoA2018_EW_Evans.pdf

Evans, C. and Hayes, B.J. (2018): British Columbia Natural Gas Atlas update 2017: recorrelation changes the picture; in Geoscience BC Summary of Activities 2017: Energy, Geoscience BC, Report 2018-4, p. 11–14, URL http://cdn.geosciencebc.com/pdf/SummaryofActivities2017/Energy/SoA2017_E_Evans.pdf

Evans, C. and Whiticar, M.J. (2017): British Columbia Natural Gas Atlas project: 2016 project update; in Geoscience BC Summary of Activities 2016, Geoscience BC, Report 2017- 1, p. 75–78, URL http://www.geosciencebc.com/i/pdf/SummaryofActivities2016/SoA2016_Evans.pdf .

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Last Modified: September 19 2020 17:01:40.