f I J c..PTb5- DI- 0-.3 The! Facies Front of the Devonian Slave , \ -' '. . Point- Elk Point Sequence In Northeastern British Columbia and the Northwest Territories
By D. L. GRIFFIN*
,.. , (Annual TVestewn lvleeting, C.l.Af., Vancouver, October, 1964) Downloaded from http://onepetro.org/JCPT/article-pdf/4/01/13/2165429/petsoc-65-01-03.pdf by guest on 26 September 2021 ABSTRACT The facies front of the Slaye Point - Elk Point sequence is the nar row 7.one of contact between the car~ bonate Slal'e Point, Sulphur Point and Pine Point formations and the "equiva , lent shales of the Horn River forma > tion. The facies front trends approxi mately north-northeast in British Co lumbia and east-northeast in the Northwest Territories. The sh"ales lie to .the northwest of the front and the carbonates to the southeast- The facies f ..ont of the Slave Point Elk Point sequence is in the order of 1000 miles in lengt.h. It extends over a maximum known stratigraphic in ( :~ terval of aDout 1,300 feet. In parts of i. the Northwest Territories. the inter val over which. the facies front is de veloped is considerably less due to the influence of a positive tectonic feature known as the Tathlina High. , In most areas, the Slave Point and Sulphur Point formations pass to shale quite abruptly and tend to be~ have as a unit in this respect_ The zone in which the Pine Point forma tion passes to'shale is much broader than that in which the b..-o overlying formations pass to shale. Three main tectonic divisions of the , ; facies front arc recognized_ It is prob ! .•' able that the major morphological features of the front result from structural controL Drilling' has shown that, in' many areas. the dolomitized Slave Point formation at the facies front contains abundant reserves of natural gas. There are sufficient grounds for be AREA OF INTEREST lieving that the underlying formations at the front also contain significant hydrocarbon reserves_ Figw'c 1.-Index map 8howillg the a1·ca disclI-sscd in the paper.
INTRODUCTION and the Slave Point - Elk Point member of the Horn River forma rocks consist of a series of lime tion in northeastern British Co N the eastern part of northeast stones and dolomites with occasion lumbia. It is the purpose of the I ern British Columbia and in al interbedded shales. Beyond a present paper to consider some as northern Alberta, the Slave Point relati veb~ narrow zone of profound pects of this zone of facies change Elk Point sequence consists of a lithologic change which trends wbich stretches from the Rocky series of evaporites and carbonates, east-northeast across the southern Mountains in the west to Great mainb~ Givetian in age_ 'Vhen part of the Northwest Territories Slave Lake in the east. (See Fig1l,.. traced to the nodh,vest the eva J and north-northeast across north 1). porites are lost from the sequence eastern British Columbia, the up The facies contact bet\veen the ",' per three-quarters of the Slave carbonates and shales occupies a Point - Elk Point sequence is rep zone usuallY several miles in resented by 11 series of shales. width, although it is considerably *Pet1"oleu1n Geologist~ British Co These are referred to the Horn wider in some areas, which ex lumbia, Dept_ of jJIines & PetToleurn River formation in the Northwest tends over a maximum strati Resow'ces, Victoria.-, B.C. Territories and to the Otter Park graphic interval of about 1,300
,Technology, .Jonuary..March~ 1965, Montreol 13 feet. This contact is termed the shown that parts of the front are Point - Elk Point sequence war facies front of the Slave Point indeed associated with reef struc rants independent study for sev Elk Point sequence_ tures, it is thought preferable to eral reasons. First, it is of great There is much evidence that, on use a noncommittal term, such as interest from a stratigraphic and the carbonate side of the front, facies front, for the whole struc tectonic point of view because it prolific organic growth occurr~d, ture until .such time that adequate repre8ents the Loundary between which, in places, resulted in the subsurface control and deta.iled two provinces of deposition which formation of reef structures. This study have established the precise wel"e maintained for a very large has led various workers to tel'm nature of this marked zone of fa part of Givetian time. To the parts of the front a reef front or cies change. northwest of the front there was barrier reef. Although it can be The facies front of the Slave an argillaceous province of deposi tion; to the southeast a carbonate evnpol'ite province of deposition. Secondly, the facies front is of in terest from a biological viewpoint because of its association with reef
._•• _••••• F':;O~5 f~OhT OF SLAVE POINT fORMATION development_ Finally, the facies front has recently assumed greut HEU.s LYING .or 5o"E DI;T4~lE fRO" r~E economic importance because drill FROhr ol.5 S~OWN.IN W~I~H TI'!E SL.oVE POINT ing by oil companies has revealedDownloaded from http://onepetro.org/JCPT/article-pdf/4/01/13/2165429/petsoc-65-01-03.pdf by guest on 26 September 2021 IS EII:T[IISIVELY OOLOIolITIIEO the presence of very considerable ....-- O:O"TOUI\·IOOII INTERVALS ", reserves of natural gas in the dolo mitized limestones of the front. "ELLS ",EIITlONEO IN TE_T I BUT NOT LT'hG It is with the last of the above • 011 ;[O:TIO" "01 mentioned aspects of the facies front that this paper is primarily concerned and therefore it will be SO' necessar:y to concentrate on what may be termed the physical as pects of the front; namely, its form, orientation and vertical and horizontal dimensions. The facies front ,vill first be described as it appears in north ea.stern British Columbia, where fairly extensive subsurface con trol enables some generalizations to be made regarding its main fea tures. Following thi~, the Grent Slave Lake area will be considered, 50' ,5H· as this represents the best known area of outcrop along the front. In order to arrive at a complete syn thesis of the front throughout its known area of occurrence, the datu from the subsurface of the south ern part of the Northwest Terri tories will then be considered. Fi nally, the main features of the front will be sllmmarized and con sideration will be given to its eco nomic aspects.
BmTISH COLUMUIA The well control in the plnins area of northeastern British Co lumbia allows the facies front to be outlined in some detail. The majority of the wells penetrate only to the Slave Point formation, and consequently it is this parl of the front that is be~t known. The facies front of the Siuve Point formation in northenstel'n British Columbia was traced out by Griffin (in press). Fi[JHTC 2, which shows the configuration of the front in British Columbia, is based on this work, and is in keeping FiglO'C 2.--Isopach map 0; the Slave Point fonnation in northeastenL British Columbia, showing the facies front a:nd line of Section AB. The position of the \\'ith the information available to j?·ont in the plains area 18 based un 'Well cont,ol. June 1. 1964,
14 The Journal af Canadian Petroleum I 2 3 4 A SA Shall Kluo Creak a-so-em Wes1 No! Imp Clerke Lake c-94-L Gulf Slares Fort Nelson No.2 Pan Am etalA"1 Snoke Ri~r c·28 D B o·5Q-C.94-J·9 c-94-L.94 o J-g o-95-J. 94·J'10 c-2B-D.9q."0-1 .. K.8 1557 Ft. KB. 1372 Ft. K.B.1299 Fl. KB.953.5 Ft .. T.O 6893FI T.O. 8039 FI. T.D.7889FI. T.O.7614 FI. I I II i ~IIlPSON-, ~ ,...., ..] ~ - ! i i, ~ L ;.. it ! - i -l ~'" ~~ , ~ ~ ~, ~ ~. ~ I .;;.B F.lI.=ES (a.aSh:~1 -.' ~ FRO>IT ~ -$ ;f ~su.:'~- r i ; ELIl POI~' , SE~eE ,n" ~'i r~ I .- ~
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[Z) _ ..4!'~...... , ...'9....., C:1"h h~ Figure 3. C1·0SS section (AB) the Gla1·ke Lake m-ea, B.G.J showing the facies front and the j01"1l!ations discllssed in this pape1-.. The line of section is shown i.n Figure 2_ Depths in feet aTe shown on well lo.gs. The Slave Point formation, British Columbia and northern Al formations) of the units of the throughout most of northeastern berta, consists, in most sectionsJ of evaporitic PaIt of the Elk Point British Columbia, varies between light-coloured dolomites and anh~' Basin (Fort Vermilion anhydrite, 200 and 500 feet in thickness and drite together with some terrigen Watt Mountain, Muskeg and Keg is made up mainly of limestones. ous clastics_ It does not pass to River formations) to the Elk Point In some areas, especiaIJy in the vi shale in the area under considera Group. However, it is considered cinity of the facies front, the Slave tion. that, for the purposes of the pres Point is dolomitized. Stromatopo Beyond the facies front. in the ent discussion, this procedure is roids are the dominant element in area of argillaceous deposition, the valid in that it helps to' emphasize the fauna of the Slave Point for Otter Park shale is underlain by a the unity of the Elk Point Basin, mation, and these organisms be limestone unit which correlates whilst at the same time enabling come especially abundant near the with the basal part of the Pine the stratigraphic changes within facies front. Point formation_ This unit is the basin to he adequately de The Slave Point formation pass termed the Lonely Bay formation. scribed without the introduction of es abruptly to shale at the_ facies (See Figure 8). new nomenclature. front; where there is sufficient On the carbonate side of the As this paper is concerned with control, the unit can be seen to front, facies changes take place the facies front. it is necessary to pass from 400 feet or so of car fairly rapidly in the upper part of ',:,:.. consider, in some detail, the Sul ::-~(. bonate to an equivalent interval the Elk Point Group, and there is phur Point and Pine Point forma :.. of shale in a horizontal distance of a facies zonation approximately tions and, to some extent, the Lone- •• 0 .~. 1000 feet. parallel to the front. Thus, to the ly Bay formation. . The Elk Point Group underlies southeast one passes from the se the Slave Point formation. (See quence described above into an eva The Sulphur Point formation is ".:;; , Figure 8). Close to the facies front, poritic series consisting of the recognized in northeastern British ' .. the Elk Point Group comprises, in Fort Vermilion anhydrite, the Watt Columbia, the southern part of the descending order, the following Mountain formation (terrigenous Northwest Territories and in parts three formations: the Sulphur clastics and carbonate), the Muskeg of northern Alberta (Belyea and Point formation· (which is consid formation (anhydrite and dolo Norris, 1962). The unit consists of W:ib ered here to include the Watt mite), the Keg River formation light-coloured aphanitic limestone J\fountain formation of northern (carbonate) .. and the Chinchaga which occurs in places in associa areas), the Pine Point formation, formation (anhydrite and dolo tion with sparites (either intra and the Chinchaga formation, The miteJ, (See Figltre 8). Farther to sparites or pelsparites). In the vi upper two formations are com the southeast, the sequence be cinity of the facies front, the posed of carbonates and both. pass comes truly evaporitic ·and the lithology of the Sulphur Point is to shale· at the- facies front, the Muskeg is represented by the often modified and it comes to re Sulphur Point being completely re Prairie Evaporites_ semble closely the· Slave Point for- placed by shale and the Pine Point In previous literature, it has not mation_ In some areas, the Sulphur being r~placed· in its upper two been customary to assign the lime Point is altered to coarsely crystal '.' thirds. The Chinchaga formation, stone and dolomite equivalents line dolomite, termed the Pres widely_distributed in northea.stern (Sulphur Point and Pine Point qu'ile formation in the" Northwest Technology, Januory-March, 1965, Montreal 15 Territories. The Sulphur Point for tongues of Horn River shale under dition to the Pine Point fOl'ml\tion, mation reaches a maximum thick lie the Sulphur Point in places and pass to shale in this area. ness of about 350 feet. are in turn underlain b}" Pine The conspicuous embayment in At the facies front, the Sulphur Point limestones (see the 'Vest Nat the front of the Pine Point fOI·ma Point fOl'mation pa~~e::5 aLJruvtly to Imp Clarke Lake c-94-L well in tion which ocellI'S in the northeast shale in much the same way as the Fig/we J). Some of these tongues corner of British Columbia and Sla've Point formation. \Vhere the of Horn River ~hale have been adjacent areas will be referred to control is sufficiently dense, as in given formal names. In the Clarke as the Cordova Embayment of the the Clarke Lake area. there are in Lake area. the Horn River tongue Pine Point. The name is derived dications that the b ...·o formations developed in VI/est Nat Imp Clarke from the Briti~h Columbia well, pass to shale almost as a single Lake c-94-L was termed the Klua Pan Am TellO CordO\'H b-34-C, in unit. For example, the Pacific formation by Gray and Kas:'lube which a well-developed Horn River Apache Fort Nelson b-76-G well (1963), and a shale tongue occupy tongue is present between depth~ shows a succession which has ing a similar stratigraphic posi of 6,220 and 6,362 feet. passed partly to shale, and about tion in the Great Slave Lake area Although the facies frunt of the 150 feet of Otter Park shale over was termed the Buffalo River for Pine Point formation differs fl'Om lies the Slave Point formation. In mation by Campbell (1950). that of the Slave Point and Sul the Apache Pacific Fort Nelson In most areas where a Horn phur Point fOl'mation~ in the L'e d-76-G well, which lies slightly River tongue occur1i it does not ex spects already outlined, thel'e Downloaded from http://onepetro.org/JCPT/article-pdf/4/01/13/2165429/petsoc-65-01-03.pdf by guest on 26 September 2021 i1i less than half a mile to the north tend far beyond the front of the little doubt that the three forma east, 450 feet of Otter Park shale Slave Point and Sulphur Point tions pass to .'ihale in the ~ame is underlain by 200 feet of Sulphur formations, At Clarke Lake, for ex general area - a possible notuble Point which has partly passed to ample, the Horn Rivel' tongue exception occurs in the area of de shale. Thus, in this area, the Slave (Klua formation) extends not more velopment of the Cordova Embay Point and Sulphur Point can be as~ than 4 to 5 miles from the main ment, The total front of the Slave sumed to pass to shale in H dis facies front. A Horn River tongue Point - Elk Point sequence cHn tance of a little over hal f a mile, A which extends over a comparable therefore, in most areas, be effec comparable situation exists be di~tance is developed in the Utahn tively mapped as a !-;inglc line. This tween the Gulf States Imp Clarke area, applies particularly to map5 of fair L b-18-D (5) and West Nat Imp ly small scale. It should be borne Clarke Lake c-8-D wells. In the northea~tern Corner of in mind. however, that such a rep British Columbia. and in the ad Unfortunately, there is not such resentaticIl, although giving a true jacent areas of Alberta and the p·cture of the front of the Slave close control on the facies changes North\vest Territories, there is evi Point and Sulphur Point forma in the Sulphul' Point formation in dence that a well-developed tongue other areas, However, the litholog tions, gives only a general indicu of the Horn River fOl'mation, re tion of the position of the zone ill ical similarity of the Slave Point placing part of the Pine Point for and Sulphur Point in the vicinit.y which the Pine Point formaLioll mation. extends well back from the p3~se~ to shale. of the facies front supports the front of the Slave Point and Sul Figure .'] show,!;; the facies front concept that they tend to behave phur Puint formations_ This Horn of the Slave Point - Elk Point se .as ,{ unit in this zone. It follows, River tongue has been penetrated quence between wells BA Shell thel'efore, that a map of the facies in six "'ells, ~hown b,:i" the symbol Killa Creek a-50-C (11 and Pan Am front of the Sla,;e Point formation HRT in Figure 4. also apPL'oximately delineates the et ai. A-I Snake River c-28-D. It front cif the Sulphu 1" Point forma It is not possible, at the present will be noted that the lVluskwa tion. time, to be certain where the facie~ shale unconformably overlies the Slave Point - Elle Point sequence The Pine Point formation front of the Slave Point and SuI· phur Point formation:.> lies in re and the correlative Otter Park is up to 800 feet in thickness and shales. The pl"e-'i\{lIskwlL eL'osion is composed mainly of limestone lation to this Horn River tongue. No ~hale equivalent of these two was mo~t marked in the area of and dolumite. The limestone, in shale deposition. mo.:::t instances, occurs immediately carbonate formations has been adjacent to the facie::; front. The penetrated in the area. However. The position of the facies front facies front of the formation dif the Slave Point formation is exten of the Slave Point - Elle Point se ~ively th~ fers somewhat from that of the dolomitized in wells sonc quence in Rocky 1\'Iountains and two overlying formations. The zone Helmet b-49-G and West Nat et al. foothills is lmown with much les~ in which the formation passes to Wildboy b-6-A (shown by the s)'m certainty than is the case for the shale is considerably 'wider than bol D in Fiuure 4.) and, on the plains area, \ValTen and Stelck the zone in which the Slave Point basis of similar occurrences of (1862) report the oc-currence of and Sulphlll' Point formations pass Slave Point dolomite, this might LeirwhYIIChlls castanea (Meek) at shale~ to shale, and there is considerable be taken as evidence that the two the base of the overlying interfingering of limestone and wells lie close to the facies front the Middle Devonian carbonates in shale at the front of the Pine Point of the Slave Point formation. In the Redfern Lake area. (See Fifl fo~ formation. (See Figure 3). vie'...· of the fact that the dolomi Ilre 2), The:,,' consider that this tization of the Slave Point forma sil is normally limited to the mid As a result of the wider zone tion can be due to a number of portion of the Givetian Stage. If over '··.. hich the Pine Point passes causes, it is considered preferable this is the case, it implie,g that the to shale and the fact that, in some to assume that the front of this uppermost carbonates at Redfern areas, the front of the Slave Point formation lies somewhat to the Lake correlate with a part of the and Sulphur Point formations was north of the above-mentioned wells Pine Point formation. The facies displaced back into an area where until drilling definitely demon front of the Slave Point and Sul argillaceous sedimentation had oc strates that the Slave Point and phur Point formations, and prob CULTed during the Pine Point, Sulphur Point formations, in ad- abl}" also a part of the front of the 16 The Journal of Canadian Petroleum 12~' ." Iir:::l:::7----.,il':-----~_'i"------..!';_:----~. 12;- JlO' ...,";:"___----,,T_-----__l"~·II.' II.· 03" NORTHWEsT TERRITORIES ., . '~ .. ., i" Downloaded from http://onepetro.org/JCPT/article-pdf/4/01/13/2165429/petsoc-65-01-03.pdf by guest on 26 September 2021 I'·,· GtlS WELLS lNWTl , . INP ~ ... MElLO F·T • ••••••• F~I[. FR;HT ~f .L&VE I'OIN1'EL~ PO"" IEQ Fig'll?"C h.-Map of t/le southmw IJart of t~e Northwest Territon"6s, _s/wwing the facie.s /1'ont of the Slave Point Elk Point sequence and the a1'eas 7JlCntlOned in the text. Tile posltl0n of tlu!. fl'ont 18 based on well cont1"ol. Pine Point formation, must there NORTHWEST TERRITORIES facies front_ The writer was able fore lie between the Redfern Lake to confirm this view during a re t-. outcrops and' the wells, situated The Great Slave Lake region has cent visit to the lake. f:' some 40 miles to the east, in which IOllg been one of the type areas for On the south shore of the lake, the complete Slave Point - Elk the Devonian succession of \Vest the Pine. Point formation is known Point sequence is penetrated. ern Canada j up to about 15 years both from outcrop and drilling; ; .. Gallant (1962) described Middle ago, it was the only area in which the formation consists o{ some 500 Devonian and early Upper De the Slave Point - Elk Point se to 600 feet of limestones and dolo vonian carbonates exposed on the quence of the facies under disclls mites, with interbedded limestone north side of the Peace River val sian was known_ It is natural, and shale in places. In some areas, :-,. therefore, that many of the for i~ ..:'- -. ley in the vicinit:~r of Bernard the upper 150 to 200 feet of the ..;.... '. ~ Creek and Wicked River. The suc mation names used in this paper formation is made up of the Buf ~ -~ j are derived from the Great Slave cession 'vas said to be ab out 2.,000 falo River shale - a tongue of the ': Lake area. In spite of the long es ) feet thick and consists of fossili Horn River formation. The pres ,".. tablished geological knowledge of ,~ " ferous limestones and dolomites. ence of the Pine Point facies of the area, ho,,,'ever, it is on]}' with . , The presence of a series of car the Elk Point Group and the devel bonates of this thickness and age in the last decade or so that the opment of a Horn River tongue in strongly sugge.sts that one is deal complicated facies relationships de the Pine Point indicate that one is ing with the Slave Point - Elk veloped there have been satisfac dealing here with a part of the .' , tol"iI~r ,. Point sequence (although possibly interpreted. Subsurface in facies fl'ont, albeit a southern mar somewhat modified in this area), formation, both from the North gin of this feature_ - and it can be concluded, therefol-e. west Territories and adjacent The Slave Point and Sulphur that the facies front, if still devel areas, has contributed considerably Point formations outcrop on both oped as a distinctive feature ·in the toward the elucidation of the stra the north and south shores of tigraphic problems presented by area, lies to the northwest of the Great Slave Lake. On the south Peace River outcrops. These fac the Devonian succession at Great shore, the Sulphur Poinf Jimestone tors, considered together with in Slave Lake. is exposed at SUlphur Point and at forrnation fronI the small amount From the .recent description of Presqu'ile Point. At the latter lo of drilling which has been carried the Devonian stratigraphy in the cality, the rock is highll' fossilifer out in the foothills, lead to an in southern part of the Northwest ous. The Slave Point limestone is ,".-- terpretation, as shown in Figu1'e 2, Territories (Belyea and Norris, not well exposed on the south shore of the facies front in the. Rocky. 1962), there can be little doubt of the Jake, but good exposures are lIfountain's and foothills 'of,British . that the Great,SJave Lake area is, found on Buffalo River, several· Columbia, in fact, an area of outcrop of the miles upstream from the mouth_ Tech!l0logy-, Janqt;lry-Mar~h, 19~5, Montreal 17 On the north shore of the lake, There is evidence from the north of the ' ..... eUs were drilled some time the Slave Point formation lies close shore which tends to support thh:. ago and therefore do not have me to the water level at Slave Point. interpretation. The LonelJ' Bay chanical logs. Farther east, however! near Vilindy limestone is exposed near the east The wells of the southern part Point and in the vicinity of Sul ern end of the Middle Devonian of the section show a normal Slave phur Bay, the Sulphur Point lime outcrops of the north shore (see Point - Elk Point ~eqLlellce; the stone and its dolomitized equiva Belyea and NOlTis, 1962)_ The four northern wells, howevel·, lie lent, the Presqu'ile dolomite, are limestone i~ succeeded by a unit on the argillaceoll~ side of the fa well exposed. which lies beneath the low ground cie~ front and show the develop The regional distribution of the of the Lonely Bay section of the ment of the Horn River and Lone Slave Point and Sulphur Point shore. The map of Douglas (959) ly Bay formations. It is probable i~ formations indicates that the facies indicates that, for a distance of that the Muskwa formation de front must lie generally to the about 30 miles, there are no out veloped in these foul' well!'i and is north and possibly also to the east crops along the shore in this re included in the Horn River forma of the present area of outcrop. The gion. Also, Cameron (1922. p. 34B) tion. presence of the Horn River forma noted that the shore became low Near Rabbit Lake (see Fi{/lfl"e tion to the north of the lake (see and swampy east of Moraine Point 4) J a number of wells have lwen Belyea and Norris, 1962) indicates (which lies about 16 miles north drilled which indicate that the east of Sulphur Bay) and that Slave Point - Elk Point .'iequence i~ that the formations pass to shale Downloaded from http://onepetro.org/JCPT/article-pdf/4/01/13/2165429/petsoc-65-01-03.pdf by guest on 26 September 2021 in this direction_ The evidence there were no outCl·OpS. The nature less than 500 feet thicl{ in the area. cited previously, indicating that a of this section of shore line sug The attenuation of the sequence southern margin of the front of gests that it is underlain by soft can be attributed to the influence the Pine Point formation is devel argillaceous deposits, which. by of the Tathlina stL"Ucture, which re· oped on the south shore, suggests analogy with occurrences else suIted in the deposition of a re that an emba~Tment of the front where, could be l·eferred to the duced Middle Devonian succ.ession exists in the basin of Great Slave Horn River formation_ The occur and probably also brought about Lake. Taken together, the data con rence of the Horn River formation increalied truncation during the sidered so far indicate that the at this locality would be quite in pre-'Muskwa erosion. front lies to the north of the Slave keeping with the configuration of Most of the wells in the Rabbit Point and Sulphur Point outcrops the facies fmllt suggested above_ Lake area appear to lie on the on the north shore and then swings At the west end of the lake, sub carbonate side of the fades front. to the south so that it lies to the surface control allows the position However, the Briggs NE Rabbit east of the outcrop trend of these of the front to be determined with Lake No.1 well shows a section in formations in the ba~in of the lake_ some degree of certainty. Figu1·e 5 which the Slave Point - Elk Point It must then swing to the east or shows a section of the Middle De sequence has partly pa~sed to northeast so that it more or less vonian rocks between the Hay Riv shale. This fact indicate~ that the parallels the Pine Point outcrops er in the south and the vicinity of facies front is developed in the of the south shore. (See Figure 4). Fort Providence in the north. Most Rabbit Lake area. 5 6 7 8 f>U~CH CEEF S.l.Y al(; /lWT HEllFH FRoe'SHER "aT rlO~ ""' ISLomo No) <. LAKE NO I RIYER TEST NO a .,-"~. ",-" ~ "-0'·'. ",.., • "l··. ~. "•.,.... '<:,"0' ,.",.,. .. ••. ,., ,.-,,'.. 00·" ... 0·". TD '01'" C 2 3 4 rlWT MJ2 rlWT NO I F ,,,..., O'l , ,.,- ~ -2,,,,-~ ,-" ....• "·'h' ",-" W • ,.". , , HAT AIYER '~--"'. ":-::~~---=.=-~~ -,,- -.-.- ";:f;r.Fl.,,ER ' ... CIES) D,c,rUM F"!iCNT _. _- -LGII:LT 8,l,y. '--'-E,, •: _ -~,- -.,- "EG RI\lER I --... ,-...... ~-., ------,~,,",,---J..,. CHI!' Fig!o'C 6.--Sectioll CD, west end of Gl-flUt Slave Lake, N.W.T., showing the Jlh·ddlc DCVOllUl1I f01"mutiom· ill tlin urca. Line of scction sh01V1~ on Figw·c 4. The fonnat1·on l01JS are based on data il·om the N.W.T. Sclwdulc of U'('llf; (196:2) _ Depths ill jeet are showll on lOcH logs, 18 The Journal of Canadian Pctralcum 2 IlUGGS TlDUf alYEI. MlU 4 IlICe! nOOT unl. No.s 6 I1UQC3 TUauT LA." Ha.I 3 IIlcel RIlIJ1' UfO Mil.' BUGGS nour liVE" liD." 7 ;. E 60"36; nilS' 6D!l';;o"W"J7' ItIfn'Ll"I,' H'g' Diu' 1OIl"9,J:i"tI' &a"n~1ZD'u' 6(Dt30;n~·n·3Q· F ~ .~a. IKa , un lJI.' 1&11. m'lIM lJI. tun ...... 'UL 43" 'ttL 3UI ...T.D. 3933"" m JU6 Tn. 31U u "" U " .. I ,II : III I; \1 (I I tit I .- 'i, I I j 1 Downloaded from http://onepetro.org/JCPT/article-pdf/4/01/13/2165429/petsoc-65-01-03.pdf by guest on 26 September 2021 ( ·11 -'- 1 ~- .... 1 i I .". 1 -" , .,.... ~. B I ~:---. -? i I I I: , "'-=_ .. ~ SUVEI'QINT- it :t'" _.. I("lt .. I :;;: -- ~- t ~cz[l ~ ( ;) i i -'1 I ~ ) - ~j - t , "1- r I -~ r.-' I~ l 5'" ~ --L ~ - > > - Figwre 6_--Section EF, showing the facies front in the Trout Lake area) N.lV_T_ Fo~'mation tops shown a~'e fT07tL N_W.T. Schedule of TJ'e1l8 (1962). Depths in feet are shvwn vn well logs. An interval vf the Fort Simpson. shul.3 is omitted from each of the logs. Linc of section is indicated on Figare 4. The Slave Point - Elk Point se laceous Middle Devonian deposits Bay formations (N.W_T_ Schedule Quence and the associated facies than into the carbonate deposits_ of Wells, 1962). It can be concluded front developed in the Trout Riv The consistent thickness is brought that the facies front of the Slave er area show certain features about by the fact that a thickening Point - Elk Point sequence lies be "\vhich are of interest in the present of the Fort Simpson formation on tween the Arrowhead River and discussion_ The Slave Point - Elk the argillaceous side of the front \Vesterol drilling areas. Point sequence is somewhat attenu compensates for the reduced Mid ated in this area (see Section EF, dle Devonian section in this area. At Nahanni Butte (see Figure Figu"e 6) and, as in the Rabbit 4), the Nahanni formation is· ex The information from the Trout posed. This formation is considered Lake area, the reduced section is River area thus provides clear J'robably a result of depositional to be of early Givetian age (Mc evidence of the development of the Learn, 1962) and it thus correlates thinning over the Tathlina High facies front_ It is of interest to and truncation during the pre with the lower part of the Pine note tbat the front is developed Point formation. The Nahanni is ]'iuskwa erosion. over the Tathlina High and that The northern four wells of Sec characteristically developed in the main effect of this structure is areas in which the Slave Point _ -tion EF lie all the argillaceous side to reduce the stratigraphic inter Elk Point sequence has passed to .' _. ·of the facies front. The logs of val on both sides of the front. ." three of the wells suggest a certain shale. It is reasonable to conclude, .amount of interbedding of lime The Arrmvhead River and Celi therefore, that the facies - front .stone and shale. These wells prob beta areas have recentb~ been the lies between the Arrowhead River .ably lie very close to the facies site of exploratory drilling, and area and Nahanni Butte, as shown -front and thus occupy an inter- some thirteen wells now give con in Figure 4- -mediate position between the argil- trol in this region. These wells in dicate that the Slave Point - Elk ·]aceous and carbonate provinces. REGIONAL CONSIDERATIONS "However, th1e Horn River forma Point sequence varies between tion has been recognized in Briggs about 750 and 1,100 feet in thick The facies front of the Slave ·Turkey Lake No.1 (N.W_T. Sched ness in the Arrowhead River area Point - Elk Point sequence is pre '. ule of Wells, 1962) and, for the and reaches a thickness in excess served in an area reaching from ·purposes of the present discussion, of 1,200 feet in the Home Signal the Rocky Mountains in the west to the Middle Devonian argillaceous CSP Celibeta No.1 well. (The lat Great Slave Lake in the east. (See ·deposits in the other three wells ter lies close to the Home Signal Figure 7). In northeastern Brit .are assigned to this unit. CSP Celibeta No. 2 well, shown in ish Columbia, the front trends ap It will be noted that the section Figure 4)- proximately north-northeast, al is arranged on a datum in the Up The Westerol wells, which were though this orientation is modified .. : . ·'Per Devonian (top of Trout River drilled in the area just to the south in some areas by projections and formation). This serves to empha of the confluence of the Liard and embayments. In the Northwest size the consistent thickness of the }Iackenzie rivers (see Figu''J'e 4) Territories, the front trends ap .Devonian deposits in the area, even do not show the Slave Point - Elk proximately east-northeast over -though the pre-Muskwa erosion Point sequence but instead pene most of its length. The facies ; .,-:-~ :. , ~-~..;~ - ~.surface .. cuts deeper into the argiI- trate the Horn River and Lonely front is in the order of 1000 miles ." .. '. -,T:chnalo9Y, January-March, 1965, Montreal lit" , C=--f7-~ilF------~"t~=------"'i"'-'-----"",,;"'~';,----\;""f":"------,"" Downloaded from http://onepetro.org/JCPT/article-pdf/4/01/13/2165429/petsoc-65-01-03.pdf by guest on 26 September 2021 \I..f) r'~lt5 I'RCNT Dr SU'1: ~DI~T-[L~ ~D.Hr sEauEH~E @, \ \, / ~11CfI OIIT of O:U.E~~ILL LAU ~o~"","'oN ,~ /- IN WE5' ? I ~ FC~IIUID~ .~o I _ LIllI' or IIUsK'U IN Eo.U \ "'<:<::G SOuTH PHCE ~IVE~ "~C~ DEFI~EC BY ~IN'" lKJT OF ELK POINT G"lI\iP / -SCAL.E- "III.. """j;-!OC ...'~'=_'~';"',;i~B,: , 101"" Figl//"{' 7_-.lfajJ of northeastcl'll British Columbia, northwcstern _4.lbcl'trl and the south('nl lw1'l of III., lIlortl''''j'Hf Ten it01"ies, showing the facies il"ont of tlie Sla'L:c Point. - Elk Poillf Sl'qw'JrCr. 20 The Journal of Canadian Petroleum \ in length; approximately half of it major morphological features of tion, or the development of :(av lies in British Columbia and h"lf the facies front developed as a re ourable reservoir characteristics by in the Northwest Territories~ sult of structural contI·oJ. The faot other means, at the facies front_ Three main tectonic divisions' of that the front crosses the Great In British Columbia, a number 1_" - •• the front can be recognized. The Slave Lake area leads at once to of wells aloe known to be capabie of ",-.. "Tathlina 'area ,vUs relativ~ly posi the conclusion that the development produeing gas from- the Pine Point tive during much ·of Givetian time, of at least part of the front was formation. Gas has been recovered ..and consequently the strata pre structurally controlled. There are from the Pine Point limestone in '. served on both sides of the front many well known faults in the vi Pan Am A-I Komie a-51-A, a well ~~- ~~'~'. in this area are much reduced in cinity of Great Slave Lake, and the which lies at the faeies hont. The thickness_ This positive element is area has been one of structural dis Pine Point dolomite is the main generally referred to as the Tath continuity since Precambrian time reservoir in the Yo}ro 'field/ and , lina High (see Figure 7). To the (see Stockwell, 1962). In the pres this occurrence also appears to be , east of the Tathlina High, a nega ent context, the faults of the East associated with the facies front. . (I Arm (see Douglas, 1959) are of ., tive tectonic environment resulted In the Northwest Territories, in the deposition of a more or less particular interest because they lie Clpproximately parallel to the facies several ''i'ells are capable of produc 'normal Slave Point - Elk Point se ing gas hom the Slave Point for front in the area. Downloaded from http://onepetro.org/JCPT/article-pdf/4/01/13/2165429/petsoc-65-01-03.pdf by guest on 26 September 2021 quence at the facies front, which mation. Examples of such wells are is now exposed along the shores of The fact that the Cordova Em :', Home Signal CSP Celibeta No. 2 Great Slave Lake. How far . the bayment of the Pine Point forma and Imp Sun Netla F-7. (See Fig front extended beyond the present tion occurs on the west; side of the u,'e 4). Although these wells do not outcrops is not known. vVest of the Tathlina High strongly suggests show extensive sections of coarselJ,r Tathlina High, a generally subsid that the embayment resulted pri crystalline Slave Point dolomite, ing flank of the faeies front devel marily from tectonic control. similar to that which characterizes oped, and is now preserved in Again, the approximate parallel many of the Slave Point producing , northeastern British Columbia and ism between the Cordova Embay ,~ wells in Bl"itish Columbia, they do the adjaeent area of the Northwest ment and the faeies front to the indieate that the Slave Point has ,. Territories. south of the Arrowhead Salient potential as a gas-bearing unit in It is possible to recognize sev suggests that an approximately the Northwes~ Territories_ eral major morphological features parallel series of faults played an on the western flank of the facies important part ill producing these In some Pal·ts of the Northwest front. During Pine Point time, the features. -The origin of such fea Territories, intervals which are Cordova Embayment extended tures .as the Utahn Emba~rment and lower in the stratigraphie sequence southeast from the main front Evie Salient is less dear, mainly than the Slave Point have' pl"oved near Trout Lake into the northeast because of the lack of detailed to contain natural gas, In the ern corner of Brit.ish Columbia and knowledge of the tectonic history Briggs Rabbit Lake No. 1 and the northwestern corner of Alber of the area, but it is probable that Briggs Rabbit Lake No. 3 wells, ta. This feature separated the Ar structural control was an impor commercial quantities of -gas were rowhead area of carbonate deposi tant factor in producing these fea obtained from a unit llsted as the tion (whieh; if it is found that the tures. Sulphur'Point formation in the Pine Point deposits there differ N.W.T. Schedule of Wells (1962). In addition to the major mor Although the Rabbit Lake ·wells significantly from those elsewhere, phologieal features of the facies might be termed the Arrowhead are situated on Cl pronounced struc front, which, it can be concluded, tural featul"e (the Tathlina High) Platform) from a large area of car result mainly from structural con bonate deposition lying to the east. they are also associated with the trol.. it is probable that there are facies front, a fact which may in In the Arrowhead River area of man~r secondary features which, bJr part account for the presence of the N ortlnvest Territories, there is analogy with modern a'reas of car a marked change in the orienta the reservoir. A well drilled in bonate deposition, Were formed by , " tion of the front from the east 1951, NWT No.1, encountered currents, winds and ,,'aves. How small amounts of gas in the Lone northeast orientation of the Nodh I:.:~- .' , ever, the definition of these fea ~ ... - : : west Territories to the mote south h' Bay formation. This well also tures will require closel:r spaced lies neal' the facies front. .. erly trend characteristic of Brit drilling along man~r parts of the ish Columbia. The feature which front and, until such control is The bituminous nature of the l'esults from this change of orien available, this interesting aspect of Middle Devonian rocks outcropping tation is termed the Arrowhead the front must remain little known. at Great Slave Lake has long been Salient. recognized. Cameron (1922, p. ,. In British Columbia, a signifi 37B) stated that pl"aetically all the ECONOMIC CONSIDERATIONS limestones which outcrop on the cant embayment of the facies front .'-', . "exists in the Utahn area - this The economic potential of the shores of the lake are more or less may appropriatel]t be termed the Slave Point formation as a gas bituminous. The writer, during a Utahn Embayment. West of this bearing unit is widely recognized. recent visit to the area, was im feature the front trends approxi At the facies front, the Slave pressed by the bituminous and pe mately east-west toward Clarke Point is prone to dolomitization tl'oliferous nature of m2nJr of the Lake. The front then swings south and the altered rock contains much Middle Devonian rocks exposed at west, giving rise to the Evie Sali of the Slave Point gas. It is evident Great Slave Lake. ent. At this point, an outlying car from the preceding discussion that The dark limestones which out bonate mass shows clear evidence the Slave Point is one of three for crop at Pine Point h-ave a distinct of reef development. This struc mations which pass to shale at the petroliferous odour when broken, ture is termed the Evie Reef. facies front, and there are grounds and, in some parts of the outcrop, In a number of areas, there is for believing that the lower forma bituminous material oCCurs in fis considerable evidence that the tions are also prone to dolomitiza- sures and small vugs in the rock. Tecb.noJogy, Januarr-March, 1965, 'Montreal 21 One of the most striking occur portance which stretches across N.'V.T.," Proc. Gcol. ABBOC. Call B7~9G. rences of petroliferoliS rock in the northeastern British Columbia and ada, Vol. 3, pp. area is seen at "Vindy Point, where into the southern part of the Dcpa?·tment of N01·tlwrn Affai/·s a?Lrl National Resources, 1962, North petroleum seepages have resulted Northwest Territories. An under west Territories and Yukon Terri in the formation of small tar pools standing of this feature will lead tory; Schedule of Wells, H)20~19(j1. in hollows in the expu::;eu Presqu' to an improved interpretation of Schedule No.2. He dolomite, The accumulations of the Devonian stratigraphy and Do/tgfas, R. J. 11'., 1959, "Great Slave tar are often associated ,,,,ith cold palaeogeography in the northern and Trom:. River 11ap-Areas, North west Tenitoric.s (85 S li.! and 95A, water sulphur springs. Similar tar part of the 'Western Canada Sedi H)," Gco!. 8"I"v. CUlarda, Paller pools a[so oCCur in the area of out mentar}r Basin. From the point 58-11_ crop of the Presqu'ile formation to of view of the economic geologist, Gallunt. B. T.. 1062, "Brief Note.:::; the nOl-th of Sulphur Bay (see· the total faciO' front of the Slave on the Lower Palaeozoic. Roc.ks oE Camel'oIl, 1917, p_ 74)_ Point - Elk Point sequence is of the Rock),' Mountains along- the. Peace RivCi·. B.C.," EdmoJl/tm Gj'fli. The above facts make it apparent particular interest because it is as Soc.. Fourth Annual Field Tl'ip that, although the formations be sociated with a ver~! favourable Guide Book, pp. 102-108. Gl'rty, F. P .. and J(assJlbt', J. R., 1963, 10\\· the Slave Point at the facies stratigraphic environment for the accumulation of hydrocarbons. ·'Geo[ogy and Strati~TElphv of front have been relatively little ClarkE'. Lake Gal; Field, North~n~t tested by drilling, there are ade ei·n Bl'iticih Columbia," Alii . ..l1-i,Hl(:. Pt'tI'Oh'lllJl Geologist.'l [J/(U.. Vol. 47, quate indications that these forma Downloaded from http://onepetro.org/JCPT/article-pdf/4/01/13/2165429/petsoc-65-01-03.pdf by guest on 26 September 2021 tions have excellent potential as REFERENCES No. :3, pp. -lG7--lB:l. hydrocarbon-bearing units both in GI"l[jill, D. L., (ill pl·e5~). "The Slave Ddyeu, H. R., and NOITis. A. IF., Point, Beaverhill Lake and Musl{wn the Northwe;:.;t Territories and 1962. "Middle Devonian and Older Furll1ation~ of Northeastern Bdthih British Columbia. It may be hoped Palaeozoic Furmations of Southern Culumbia and Adjacent. Are[\~," that there will be a future tend District of :.Hackenzie and Adja(~ent B.C, Dept. of Mil/c's lWei Pd. R('s., ency to think in terms of the po Areas," G,'ol, Sun'. Canada, Paper Bull. No. 50. tential of the Slave Point - Elk 62-15. JlcLanll, D. .I., Ulti2. "Middle and Cr01ICI'oH, ,.1. E.. 1£117, "Reconnais Earb' Uppei· Devonian Rhyncho Point sequence at the facies front ~ance on Great Slave Lake, Nort.h neJloid Brachiopods from Western rather than just the potential of west Territoi·ies," Gcol. Surll. CaJ~ Canada." G(·f,{. SIlJ"l', CaJlrH(n, Bull. the Slave Point fOl·mation. uda, Sum. Rept., 1916, pp. 66-7G. 8G_ Camerol/, A_ E., 1918. "Explorations Stoct.-werl, C. H_, 191i2. II A TectoniL" in the Vicinitv of Great Slave :\1ap of the CanadiHn Shield," in Lake," Geoi. S~IJ"I}. Canada, Sum. The Tee/oMcs of tla' CUJI(uliaJl CONCLUSION Rept., 1917, Pt. C, pp. 21-28. Shield, edited by J. S. Stevenson_ ROIl. Soc. Ca1w.dcI, S1'. PrIll. Nu. ·L Came}"on, .d. E." 1922, "Hay and Buf Pl'es~. In c.onclusion, the material con falo Rivero,;. Great Slave Lake, and Ulliver:-;ity of TOI·onto ~idered in this paper indicates that Adjacent Country," Geol. Sur/). WU/"l"e1I, P. S., and Stf'ld,·, C. R_. the f"lcies front of the Slave CUlw-lla, Sum. Rept., 1921, Pt. B, HIG2, "Western Canadian Give pp. 1-44. tian:· .4flJrrta Snc. Pdl·oh·/tm al'of. Point - Elk Point sequence is a Campbell, N .. 1950, '''The :i'diddle De of/ists .}Oll}"., Vol. 10, No.6, IJP_ stratigraphic feature of major im- vonian in the Pine Point Area, 273-291. REPRINTS OF TECHNICAL PAPERS EADERS of 1'he Jow'nal of Canadia.n Petroleum Technology are reminded that reprints of 'most R of the technical papers that have been published in these pages are available from the Journal Business office. The price i:::: fift}r cents each to the membership of The Institute of Mining and .i\'1etallnrgy a!1d one dollar each to non-members_ 22 The Journal of Canadian Petroleum