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Canadian Geothermal Data Collection -
Deep permafrost temperatures and thickness of permafrost

Alan E. Taylor(1), Margo M. Burgess (2), Alan S. Judge (3), Vic Allen(3) and Anne Wilkinson (3)

(1) retired, Geological Survey of Canada; now at 9379 Maryland Drive, Sidney, BC V8L 2R5 Canada (250) 656-0690 altaylor@kcorp.com (2) Geological Survey of Canada, Terrain Sciences Division, 601 Booth Street, Ottawa, ON K1A 0E8 Canada (613) 996-9317 burgess@NRCan.gc.ca (3) retired, Geological Survey of Canada

PREFACE

Over the past thirty years, precise ground temperature logs to depths greater than 125 m have been obtained from many resource exploration holes in and adjacent to the permafrost regions of northern Canada. Most of these data were acquired by the Geothermal Service of the Earth Physics Branch, EMR Canada (later amalgamated with the Geological Survey of Canada), in cooperation with the exploration industry and the regulatory agencies. This report presents the entire data set as digital files for the area north of 60 degrees north latitude. Some data are included for holes less than 125 m depth, but such data is incomplete at this time.

Table 1 lists the sites reported here, and Figure 1 is a map showing their locations. Figures 2-9 are more detailed maps annotated with the permafrost thickness measured or estimated at each site. Digital data from a site of interest may be found in the database by referring to the Table or Figures for the site number.

An overview of the history of deep temperature observations in the permafrost regions of northern Canada is followed by a brief discussion on data acquisition and accuracy, the thermal disturbance due to drilling and the determination of permafrost thicknesses. Reference to other complementary ground temperature and permafrost thickness data is made. The report is accompanied by a selected bibliography of scientific papers and miscellaneous publications based on the data.

Depths to the base of permafrost in the Canadian Arctic Archipelago range from 143 m to 726 m (Fig. 2), in the Mackenzie Delta - Beaufort area from 0 m to 663 m or more (Fig. 7-9) and in the remainder of the northern mainland, from 0 m to more than 500 m (Fig. 3-6).

CONTENTS

1.0 Introduction
     1.1 Other sources of temperature data
2.0 Acquisition of data
     2.1 Preservation of wells for temperature measurements
     2.2 Acquisition and accuracy of data
     2.3 Estimating undisturbed downhole temperatures
3.0 Calculation of permafrost thickness
4.0 Closure
5.0 Acknowledgments
6.0 References
     6.1 Scientific papers
     6.2 Canadian Geothermal Data Collection 1974-1982
     6.3 Sources of other deep temperature and permafrost data

Table 1
Figure Captions
Figures 1-11

1.0 INTRODUCTION

In the past thirty years, industry and government have become increasingly aware of permafrost as it affects the north, the exploration and eventual production of natural resources. The knowledge of permafrost distribution and its characteristics -its thickness, temperature, composition and physical properties -has grown immensely over this period.

In northern Canada, research on these topics, and geothermal research in general, was for many years hampered by logistics and the enormous cost of operating a drill-rig in the Arctic. Pioneering deep geothermal studies were made by Hemstock (1949) and later by Garland and Lennox (1962) at Norman Wells, N.W.T. (site 88, Fig. 1, 6), by Bremner (1955) at Resolute Bay in the High Arctic (site 901, Fig. 2), by Jacobsen (1963) and the United States Geological Survey at Winter Harbour (site 73, Fig. 2), by Beck and Sass (1966) at the Muskox Intrusion (sites 902, 903, Fig. 5), and by Mackay (1967) in the lower Mackenzie Valley (Fig. 7). Many of these studies led to a greater understanding of permafrost. For example, Misener (1955), using Bremner's work, was able to determine a terrestrial heat flow at Resolute Bay: the resulting high value caused Goguel (1956) to consider the effect of surface temperature change and Lachenbruch (1957) to consider theoretically the effect of a shoreline on the underground thermal regime and permafrost.

Early permafrost maps showed the distribution of permafrost but few permafrost thicknesses were reported (Jenness, 1949; Bateman, 1949). The first detailed map of permafrost distribution (Brown, 1967) reported only two thickness determinations in the Arctic Archipelago (Figure 2), although more thicknesses were reported for the mainland because of the greater exploration and engineering activity in that area of generally thinner permafrost.

A more complete regional geothermal study became feasible in the late 1960's because of the increased activity associated with resource exploration and development. With the cooperation and assistance of the petroleum and mining industries and the government regulatory bodies, the Geothermal Service of the Earth Physics Branch, EMR Canada (later amalgamated with the Geological Survey of Canada (GSC)) accumulated temperature and thermal property data to depths greater than 125 m at some 140 sites in the permafrost regions of Canada (Fig. 1; Table 1). Data were acquired also from many short boreholes that generally did not penetrate the base of permafrost. Description of the program of the deeper well logging is found in early papers (e.g. Jessop, 1970; Judge, 1973a; 1973b; 1974). These data were published regularly as new wells became available in the Canadian Geothermal Data Collection - Northern Wells series (Taylor and Judge, 1974; 1975; 1976; 1977; Judge et al., 1979; 1981; Taylor et al., 1982). In most cases, these publications provided the first measurements of the depth to the base of permafrost across northern Canada.

This report presents the entire data set (to 1995) of ground temperatures and permafrost thicknesses in digital form. The formats of the digital files are described in a separate section. Figure 1 shows the location of all sites and is keyed by GSC file numbers to Table 1 and throughout the digital database. Figures 2-9 are larger scale maps (proceeding north to south, east to west) depicting permafrost thickness determinations. The maps and tables may be used to locate sites of interest and data in the digital archive. The petroleum exploration wells and mining holes utilized to obtain these ground temperatures experience a considerable thermal disturbance in the process of drilling (e.g. Fig. 10); the acquisition and accuracy of temperature data under these circumstances and the estimation of equilibrium (or undisturbed) temperatures from this data set is described in section 2 (Fig. 11). The calculation of permafrost thickness using a series of logs on a well and its drilling history is described in Section 3.

Many papers and reports have considered the scientific and engineering implications of the data; a selection of these publications is listed in the bibliography.

1.1 Other sources of temperature data

This data set is believed to contain all precise non-confidential subsurface temperature information from holes deeper than 125 m north of latitude 60 degrees north. In most cases, data from holes less than 125 m are not included here but a "shallow" database is in preparation.

A number of contract reports provide related, but less precise, deep ground temperature and permafrost measurements from a much larger number of arctic petroleum exploration wells. Three studies have examined downhole geophysical logs from all petroleum explorations wells throughout the north and have extracted the thickness of the frozen section based on electrical and acoustic properties (D & S Petrophysical, 1983; Hardy and Associates, 1984a, 1984b). Two studies have derived deep temperature information from various bottom-hole temperatures and drill-stem tests undertaken during the drilling of the wells (Geotech, 1983; 1984). The data obtained in these ways are not of the same accuracy as those presented here (e.g. Taylor and Judge, 1981), but complement the precise data by providing permafrost information from a wider geographic distribution, and temperature estimates at greater depths.

2.0 ACQUISITION OF DATA

The data reported in this collection were acquired over three decades of field work, starting in the late 1960's and extending across arctic Canada. Permission to make ground temperature measurements at these sites was obtained through arrangements with the lease-holder or well operator and the regulatory agencies. Logistics of access to sites was a particular problem in this remote area. Helicopters were used generally in the western arctic (Mackenzie Delta and Valley, Fig. 6-9) and fixed-wing aircraft in the high arctic (Arctic Archipelago, Fig. 2), where a greater range was required. The remoteness of site locations and the lack of infrastructure precluded the use of conventional industry downhole well logging systems or of truck-mounted units.

2.1 Preservation of wells for temperature measurements

In the deep (greater than 125 m) wells considered here, the thermal disturbance due to drilling through porous, frozen unconsolidated sediments or rock may take years to dissipate (Lachenbruch and Brewer, 1959) and temperatures must be monitored over several years in order to calculate an equilibrium temperature profile, or to estimate undisturbed temperatures. Simple techniques were developed to facilitate the measurement of well temperatures in permafrost for several years after drilling was completed (e.g. Jessop, 1970; Judge, 1973a; 1974). In mining exploration holes (e.g. site 114), a multithermistor cable was allowed to freeze into the drillhole. In petroleum exploration wells (e.g. site 197), such cables rarely survived freezeback in the large, cased holes and a different approach was needed. Before the drill-rig left the site, the drilling mud above the regulatory cement plug at the base of the permafrost casing was displaced with diesel fuel. This allowed subsequent re-entry of the well for an indefinite period, generally giving access through the permafrost section, and tens of metres to a few hundred metres into the unfrozen horizons below. Canadian regulatory agencies assisted with the development of these procedures.

2.2 Acquisition and accuracy of data

These completion arrangements permitted the periodic logging of the drillhole or well with light-weight, portable equipment. Where a permanent multithermistor cable was installed, thermistor resistances were measured at the cable termination with a precision Wheatstone-type bridge. In more recent years, a high-quality electronic multimeter whose sensing current did not create appreciable self-heating of the thermistors, was also used. In the diesel-filled wells, a light probe containing a calibrated thermistor was lowered in stages down the well and thermistor resistances were measured with the Wheatstone bridge. More recently, several wells were logged with a quasi-continuous, portable downhole logging system. Temperatures were derived to an accuracy of 0.02 degrees Celsius and a resolution of several millidegrees (thermistors used in the program were calibrated in-house to an accuracy of 0.01 degrees Celsius, traceable to standards at the National Research Council of Canada).

2.3 Estimating undisturbed downhole temperatures

Temperature logs reflect the considerable thermal disturbance caused by drilling. This is particularly apparent in petroleum exploration wells because of the much longer times involved in drilling these wells to total depth (months), compared to mining exploration holes (days). The disturbance also persists for a much longer time in holes in permafrost than in unfrozen areas, or in the permafrost section of a hole compared to the unfrozen formations below (e.g., Fig. 10). Temperatures taken periodically following completion of a well may provide insight into the thermal dynamics of the well (Jessop, 1970; Taylor, 1979; Taylor and Judge, 1981).

An estimate of undisturbed ("equilibrium") temperatures may be made from a series of downhole temperature logs taken over a period of time following completion of the hole. A model suggested by Lachenbruch and Brewer (1959) may be used:

T(t2) = Teq + (q/4*pi*k) ln (1 + t1/t2)

where

T(t) = temperature at depth of interest at time t following completion of drilling (degrees Celsius)

Teq =equilibrium or undisturbed temperature at depth of interest (degrees Celsius)

q = effective heat source strength due to drilling (W/m)

pi = 3.14159...

k = thermal conductivity of formation (W/mK)

t1 = drilling duration at depth of interest (s)

t2 = time between completion of drilling and taking of temperature log (s)

Temperatures logged at several times following drilling, when plotted against the logarithmic time function (i.e., ln [1+t1/t2]), may approximate a line of slope q/4*pi*k and a temperature intercept of Teq. Figure 11 shows the data from the same Mackenzie Delta petroleum exploration well plotted in this way.

The logarithmic method, strictly speaking, is valid only if no phase change affects the return to equilibrium. Only data from below the permafrost can be used to determine the base of permafrost unless the permafrost has very low porosity or has refrozen. However, as additional temperature logs are taken (in this data set, usually annually), the accuracy of the equilibrium estimate increases. For ratios t2/t1 greater than 25, calculated equilibrium temperatures are generally within a few tenths of a degree of undisturbed temperatures. Such estimates converge more quickly for Arctic Archipelago wells, and generally five years of annual data are sufficient to attain this accuracy.

3.0 CALCULATION OF PERMAFROST THICKNESS

One of the prime purposes of this data collection is the determination of the thickness and distribution of permafrost in northern Canada. Table 1 lists all sites and the depths to the base of permafrost determined from the temperature data in this collection, in north-to-south order.

Description of the contents of the table, column by column, is provided after the last entry. Columns 1-9 give the site name and location details. Column 10, titled "PF", gives the best estimate of the depth to the base of permafrost, in metres below the ground surface. This depth has been calculated in a variety of ways depending on the number of logs made and the total depth logged. Where three or more logs have been run, the depth has been determined by a return to equilibrium procedure, as described in Section 2.3. This method of determination is noted by the "E" in the preceding column (9). In wells where temperature measurements did not completely penetrate the permafrost and temperatures have been extrapolated to greater depths to intersect the 0 degree Celsius isotherm, the estimate of permafrost thickness is preceded by "X" in column 9. In cases where the measurements are unsuitable for extrapolation, the thickness estimate is preceded by ">". A few wells have been logged once or twice only and the listed value is derived from direct interpolation of the latest log. Such values are followed by a plus (+) sign and probably underestimate the permafrost thickness.

In wells drilled through permafrost with high ice content, most logs made within a few months of well completion reveal a temperature "jump" of several degrees across a small depth interval (e.g., Fig. 10). On subsequent logs, the depth of this jump has been found to lie a few metres to a few tens of metres above the base of permafrost and has been interpreted as indicating the base of the frozen, or ice-bonded section (Jessop, 1970; Taylor and Judge, 1981). At sites where this has been observed, the depth to the base of ice-bonded permafrost is given in the column labelled "IBPF" (column 11) to an accuracy that is determined by the vertical spacing of the temperature observations (column 12).

Some assessment of the degree of drilling disturbance still residual in the well at the time of the latest log is given in the column labelled "t2/t1" (13). This value expresses the ratio of the time between well completion and latest log to the drilling time. Generally, a ratio greater than 25 indicates measured temperatures are within a few tenths of a degree Celsius of the final equilibrium, or undisturbed values. This guide may not hold in horizons of excessive disturbance.

Permafrost thicknesses may be modified locally by the proximity to bodies of water or coastlines (e.g. Taylor, 1991). The distance (km) to the nearest significant body is given in the column labelled "water" (14).

Column 15 gives the reference to the government publication where the data were earlier published (listed after last entry in Table). Column 16 ("Deep log") lists the depth attained by the deepest log on the well. Column 17 notes the technique used to measure the temperatures on the well (Section 2.2).

4.0 CLOSURE

This represents an initial attempt to bring together these data into an accessible digital database. The inclusion of a few additional sites with deep (greater than 125 m) temperature and permafrost data not reported here, and additional data and descriptive information on all sites, is planned. The reader is asked to advise of any omissions, or to contribute data unknown to us. A companion data collection of shallow (less than 125 m) ground and permafrost temperature data is presently in preparation.

5.0 ACKNOWLEDGMENTS

We acknowledge the many individuals and organizations who assisted in the data acquisition. Many petroleum and mining exploration companies have made wells available to us and assisted in the data acquisition. We thank the Canadian Department of Indian and Northern Affairs and the Canada Oil and Gas Lands Administration for approving the extended use of these wells for temperature observations. Logistic support for the work was provided by the Polar Continental Shelf Project, the Arctic Scientific Resource Centres at Inuvik and Igloolik, and by the Earth Physics Branch, EMR and the Geological Survey of Canada. Drs. A.M. Jessop and T. Lewis of our group provided guidance and assistance, particularly in the early years of the project. Assistance in equipment preparation and field work was provided by P. Lanthier and numerous summer and CO-OP students.

For guidance and assistance in the preparation of this release of the digital database, we thank Claire Hanson and Chris Haggerty of the World Data Centre-A, Boulder, CO. Finally, we thank the Data and Information Working Group of the International Permafrost Association for their vision.

6.0 REFERENCES

6.1 Scientific papers

1949		Bateman, J.D.
		Permafrost at Giant Yellowknife.  Transactions, Royal Society of Canada . v. 43, ser. 3(4), p. 7-11.

1966		Beck, A.E. and Sass, J.H.
		A preliminary value of the heat flow at the Muskox intrusion near Coppermine, N.W.T.  Earth and Planetary Science Letters 1, 123-129.

1948		Birch, F.
		Effects of Pleistocene climate variations upon geothermal gradients.  American Journal of Science 246, 729-760.

1955		Bremner, P.C.
		Diamond drilling in permafrost at Resolute Bay, N.W.T.  Publications, Dominion Observatory (Government of Canada) 16, 365-390.

1967		Brown, R.J.E.
		Permafrost in Canada (map).  Division of Building Research, national Research Council of Canada (map NRC 9769) and Geological Survey of Canada (map 1246A).

1978		Brown, R.J.E.
		Permafrost. Hydrological Atlas of Canada. Fisheries and Environment Canada, Ottawa.

1962		Garland, G.D. and Lennox, D.H.
		Heat flow in western Canada.  Geophysics Journal 6, 245-262.

1956		Goguel, J.
		Influences des variations de la temperature superficielle sur le degre geothermique, en particulier dans le cas d'un sol gele permanent. Annales Geophys. 12, 183-201.

1949		Hemstock, R.A.
		Permafrost at Norman Wells, N.W.T.  Unpublished report, Imperial Oil Ltd., Calgary, Canada.

1963		Jacobsen, G.
				Deep permafrost measurement in North America. Polar Record 11, 595-596.

1949		Jenness, J.L.
		Permafrost in Canada.  Arctic 2, 13-27.

1970		Jessop, A.M.
		Depth of permafrost.  Oilweek, Jan. 12, p. 22-25.

1973a		Judge, A.S.
		Deep temperature observations in the Canadian North. in, Permafrost, Second International Conference, National Academy of Sciences, Washington, DC. p. 35-40.

1973b		Judge, A.S.
		The prediction of permafrost thickness.  Canadian Geotechnical Journal 10, 1-11.

1974		Judge, A.S.
		Geothermal measurements in northern Canada. in, Proceedings, Symposium of geology of Arctic Canada. Geological Association of Canada - Canadian Society of Petroleum Geologists, Saskatoon. p. 301-311.

1957		Lachenbruch, A.H.
		Thermal effects of the ocean on permafrost. Bulletin, Geological Society of America 68, 1515-1530.

1959		Lachenbruch, A.H. and Brewer, M.C.
		Dissipation of the temperature effect in drilling a well in arctic Alaska.  U.S. Geological Survey Bulletin 1083-C, p. 73-109.

1967		Mackay, J.R.
		Permafrost depths, lower Mackenzie Valley, N.W.T. Arctic 20, 21-26.

1955		Misener, A.D.
		Heat flow and depth of permafrost at Resolute bay, Cornwallis Island, N.W.T.  Transactions, American Geophysical Union 36, 1055-1060.

1978		Taylor, A.E.
		Temperatures and heat flow in a system of cylindrical symmetry including a phase boundary; Earth Physics Branch, Geothermal Series 7, 95 p.

1979		Taylor, A.E.
		 	The thermal regime modelled for drilling and producing in permafrost; Journal of Canadian Petroleum Technology 18, no. 2, 59-66.

1981		Taylor, A.E. and Judge, A.S.
		Measurement and Prediction of Permafrost thickness, Arctic Canada; Technical Papers, 51st Annual Meeting, Society of Exploration Geophysicists, v. 6, p. 3964-3977.

1991		Taylor, Alan E.
		Marine transgression, shoreline emergence: evidence in seabed and terrestrial ground temperatures of changing relative sea levels, Arctic Canada; Journal of Geophysical Research 96B, 6893-6906.

6.2 Canadian Geothermal Data Collection 1974-1982

These are references to previous publications of the data in the present database. Arranged by year.

1974		Taylor, A.E., and Judge, A.S.
		Canadian Geothermal Data Collection - Northern Wells, 1955 to February 1974; Earth Physics Branch, Geothermal Series 1, 171 p.

1975		Taylor, A.E. and Judge, A.S.
		Canadian Geothermal Data Collection - Northern Wells 1975; Earth Physics Branch, Geothermal Series 3, 170 p.

1976		Taylor, A.E. and Judge, A.S.
		Canadian Geothermal Data Collection - Northern Wells 1975; Earth Physics Branch, Geothermal Series 6, 142 p.

1977		Taylor, A.E. and Judge, A.S.
		Canadian Geothermal Data Collection - Northern Wells 1976-77; Earth Physics Branch, Geothermal Series 10, 194 p.

1979		Judge, A.S., Taylor, A.E., and Rutledge, L.
		A supplement to the Canadian Geothermal Data Collection - Northern Wells 1977-78; Earth Physics Branch, Open File 79-13, 64 p.

1979		Judge, A.S., Taylor, A.E., and Burgess, M.M.
		Canadian Geothermal Data Collection - Northern Wells 1977-78; Earth Physics Branch, Geothermal Series 11, 187 p.

1981		Judge, A.S., Taylor, A.E., Burgess, M.M., and Allen, V.S.
		Canadian Geothermal Data Collection - Northern Wells 1978-80; Earth Physics Branch, Geothermal Series 12, 190 p.

1982		Burgess, M.M., Judge, A.S., and Taylor, A.E.
		Yukon ground temperature data collection - 1966 to August 1981; Earth Physics Branch Open File 82-1; Energy, Mines and Resources Canada, Ottawa, Ontario, 138 p.

1982		Taylor, A.E., Burgess, M.M., Judge, A.S., and Allen, V.S
		Canadian geothermal data collection - Northern Wells 1981; Earth Physics Branch, Geothermal Series 13, 153 p.

6.3 Sources of other deep temperature and permafrost data

These are references to data acquired through analysis of downhole geophysical well logs.

1983		D&S Petrophysical Co.
	Study of geophysical well logs in Mackenzie Delta-Beaufort Sea area to outline permafrost thickness and/or gas hydrate occurrence.  EMR Canada, Earth Physics Branch, Open file 83-10 (242 pages). 

1983		Geotech Engineering Ltd.
		Subsurface temperature data from Arctic wells. EMR Canada, Earth Physics Branch, Open file 83-11 (401 pages).

1984		Geotech Engineering Ltd.
		Subsurface temperature data from wells north of sixty, Yukon - Northwest Territories.  EMR Canada, Earth Physics Branch, Open file 84-28 (557 pages).

1984a		Hardy and Associates Ltd.
	Study of well logs in the Arctic Islands to outline permafrost thickness and/or gas hydrate occurrence. EMR Canada, Earth Physics Branch, Open file 84-8 (215 + 159 pages).

1984b		Hardy and Associates Ltd.
	Study of well logs in the western Northwest Territories and Yukon  to outline permafrost thickness and/or gas hydrate occurrence.  EMR Canada, Earth Physics Branch, Open file 84-27 (290 pages)

Site maps, figures, and additional documentation

Table 1 A full listing of the stations contained within this data set. The meta data includes geographic parameters such as latitude and longitude as well as some permafrost properties information.

Figure 1 Sites included in the IPA-CAPS digital database "Canadian Geothermal Data Collection - deep permafrost temperatures and thickness of permafrost". Generally, only sites having data deeper than 125 m are shown. The numbers are Geological Survey of Canada file numbers used to identify sites in Table 1 and throughout this report.

Figure 2 Site locations for the Canadian Arctic Archipelago. Depths to the base of permafrost are given in bold text in metres; the numbers in brackets are GSC file numbers used in Table 1 and throughout this report.

Figure 3 Site locations in the eastern Arctic. Depths to the base of permafrost are given in bold text in metres; the numbers in brackets are GSC file numbers used in Table 1 and throughout this report.

Figure 4 Site locations in the east-central Arctic. Depths to the base of permafrost are given in bold text in metres; the numbers in brackets are GSC file numbers used in Table 1 and throughout this report.

Figure 5 Site locations in the west-central Arctic. Depths to the base of permafrost are given in bold text in metres; the numbers in brackets are GSC file numbers used in Table 1 and throughout this report.

Figure 6 Site locations in the western Arctic. Depths to the base of permafrost are given in bold text in metres; the numbers in brackets are GSC file numbers used in Table 1 and throughout this report.

Figure 7 Site locations in the Mackenzie Delta - Beaufort Sea area. Depths to the base of permafrost are given in bold text in metres; the numbers in brackets are GSC file numbers used in Table 1 and throughout this report.

Figure 8 Site locations in the Richards Island area, Mackenzie Delta. Depths to the base of permafrost are given in bold text in metres; the numbers in brackets are GSC file numbers used in Table 1 and throughout this report.

Figure 9 Site locations in the Parsons Lake area, Mackenzie Delta. Depths to the base of permafrost are given in bold text in metres; the numbers in brackets are GSC file numbers used in Table 1 and throughout this report.

Figure 10 Temperature logs taken over several years at dates indicated, at site 193, the Ikhil I-37 petroleum exploration well, Mackenzie Delta (Fig. 7). These logs illustrate the thermal effects of drilling and may be used to estimate the undisturbed, or equilibrium temperature Teq (Fig. 11; Section 2.3). Well was drilled between April 10, 1973 and December 12, 1973. (From Taylor et al., 1982)

Figure 11 Temperatures measured over several years at the well in Fig. 10, plotted versus a logarithmic time function to illustrate a method that may be used to calculate equilibrium temperatures. The dates of the individual logs are given along the lower margin.