A Seismic Perspective on the Panny and Trout Fields of North-Central Alberta

CANP.DIAN JOURNAL OF EXPLORATWN GEOPHYSlCS ““L, 24, NO 2 (DECEMBER 1988,. Pi 154~165 A SEISMIC PERSPECTIVE ON THE PANNY AND TROUT FIELDS OF NORTH-CENTRAL ALBERTA N.L. ANDERSON’, R.J. BROW@ AND R.C. HINDS~ r they overlie a thin veneer of basal Paleozoic elastics (Granite Wash) and the Precambrian. They, in turn. are we presenl,hPx exampleseismic Secfi<w k”,” the general overlain by the interlayered anhydrite salts and carbonates scncr aira Of *,tJerta.two from IhCPanny fiC,d and one from the of the Muskeg Formation. In places, Precambrian base- Trwt field. The seismicsxprcsbiooh ol variousstratigraphic w~in menr highs may he overlain by middle Muskeg units in the IhaI arc of *ignilicsncr in the interprrtsriw arc discuisrd. ‘The absence of the Keg River Formation and the basal portion Keg River Formati”” ii rile principntICsErYllir tack\ I” ,k scncx of the Muskeg Formation. In such areas, the sahs of the aru and typically is productivewhere draped acres or wedge* Muskeg Formation may have been extensively dissolved out againsl Precambrian 5Iructural highs. The Keg Rircr Formarion is overiain by thr Murkcg ~ormaiion (~tw haral (Anderson et al., IYXYn. b). Murksg anhydriteilnd interlayercds”cceSSi”n “1 Murk&, SiikS. The Keg River Formation is the principal reservoir imhydrites andcarhonaws). Ihe WauMoumin Fumwtionand the facies at the Panny and Trout fields of the Senen area. the Slave hint Formation. The contact bcLwcenIhe Kef Rivc~ basal Paleozoic clestics being a secondary target (Figure Formnlionan* tile basalMurkeg aohydritedoer no, genrmte8 I). Generally. reservoirs occur where the Keg River discernible seismic event.Thrrefwr, itm~tuw iatthis level cnusthe inferred on the hasis of lime-sIructw:II relief alunp three other Formation is structurally closed across, or against the rn”X prominenrref,ec,ionr: ,llC Prccambri;mthe txse of the flanks of, underlying Precambrian highs. Such structures M”S!q sat,and rile SlavePoint events.I” ,h”W areaswhere the are usually characterised on seismic data by time-structural Precambrianis nwr,ain hy middleM”S!q ,llli,S. rctlecf,o”-c”n,i- closure at the Slave Point, base of the Muskeg salt, and nucly prohlrms are encounWrcd.In theseplaces. chr overlying Muskegsa,,s ilaw co”m,nly heenleached and. a!. a ES”,, “f co- Precambrian horizons; also by lateral variations in the lapie, the Slave Poinl Formarion is olten anomalousiy low. amplitudes of thehe events. Exceptions occur where ahugh the Mukeg does nut Ihave10 be in ccmacl with the Precambrian structural highs have triggered extensive post- Precambrian fi~rhalt rcrnwd to hwc occurred.On rhe baskni he dcpositionel dissolution of the Muskcg Formation salts. In amplitudeof Ihe PrrcamhriallCV2”~ and lk prr\mcc or ahscnce such areas. the Slave Point Formation can be anomalously “f dimractions.ilrcas “f CxtmSiYCdisi”l”tion alid b*ssmenrS,T”C~ low as a result of the leaching and subsequent collapse. fural lowscan usui~liybe differentiated. Very little has been publicly presented on the Senen area, either of a geophysical or a geological nature. Campbell (1987) discusses the stratigraphy and facies of the area; Cant (198X) discusses the regional structure and During late Eifelian to early Givetian time (Figure I). tectonic development of the Peace River arch and adjacent the Senex area of north-central Alberta. to the northeast of areas, while Mitchell (1988) summarises (from an oral pre- the Peace River arch, was part of the fringing Keg River sentation) many of the seismological aspects. Formation carbonate shelf (Figures 2 and 3). These shelfal Throughout this paper, such expressions as f/v KCE carbonate sediments of the present-day Keg River R&I. hwixn OT PW?I, or mflwrion refer to the top of the Formation have a variable argillaceous content. Typically. named unit unless explicitly otherwise stated. Similarly, Manuscnpi receivrd by rhe Editor September 9, 198X: revised manuscript received October 25. lUXX. ‘Departmenl otc?eotogicai sciences. Ohio University. Alhem. Ohio 45701-2979 ‘Department ofCe”logy and Gei,physici. University ofcaigary, Calgary. Alhem T2N IN4 Xkpartment of Geology, University of Pretoria, Preroria. Republic of South Afncs OWI We are grateful to Associate Editor Edward 0. Lalnnde for handling the review proccas for this paper and to the three reviewers hr their helpiul comments. We would also like to thank Mr~ Paul C. Slamino uf Home Oil Lrd~ and ivtr~ C.M. Cmor of BP C;mad;i Ltd. for reviewing this paper md providing uq with hrlpful f”ggelli<m WC prmf”lly ackllowlcdge Dr,. C,aralce v. Camphrll an<, Fiank A. Smak~s Gmakrs Carnphrli Ge”c”nsuliinp Lid., for permission to reprudusc Figureb 2, 3 ilnd 8 and for thcic kind considerahm in providing us wilh figure originals. The 2-D beihmic naxklr were generaled wing the GMA Structural Modelling Sy*trm uf Gcuphy5icill Micro Compulcr Applicdtiunr (Intcmatiuivd~ Ltd. The fvm seismic linrh (rum the Pvnny arca and the seismic line from the Trout xea were provided by Sigma Explorariun (197X) Ltd. and Chevron Cam& Ltd.. rcrpecriveiy. These data weri‘ reprocessed by 17&A (Invrrse Thwry and Applications Inc.) and Chevron Canada Rc~ourccs Lid.. rrsprctively. Pxlial ruppan wab pruvidrd hy the Natural Scirncer and Engineering Research Council of Canada hrcwgh an operadng grant to R.J. Brown. I54 SElSMLC PERSPECTlVE ON PANNY AND TROUT FELDS 155 ‘ERIOD EPOCH CENTRAL NORTHWESTPLAINS JORTHEASTPLAiii “Dn*trs I PLAINS AND DEEPBASIN AND EASTERNPLAINS w ERMIAb - EARLY -iAl ATE C&R $ 5 EARLY 2 CARB 2 +-2%+-l BANFF . - E LSSlO”0 lliMlNH,l t- I ;i i / ,RllHl, I I GIYIIIA :I PRAIRIE :I +- KEG RIVER- lOXI”1191,111 . WINNIPEGOSIS WILlAl Ial.--z+ UPPERCHINCHbCA CONTACTRAPIDI I 1- COLD LAKE - I LM5tA’ ,1*,111*. ‘o’mRG mm stIl mm i Ll# l GRANITE WASH SILURIAN l,.“,i.* LATE DEADWDOD DEADWOOD I I I / I,, I I1 _ Pm.. MIDDL EARLIE L -- ‘\ BASALSIT EARLY PROIEROZOIC L AR‘HEAN MAINLYARCWAN TO Ed ; PRO,mOzOICGRANITK AND MnAMcmPHIC ROCK5 Fig. 1. Stratigraphic chart for the Paleozoic of central and northern Alberta (modified after AGAT Laboratories, 1988) SHELF CARBONATE ; SlLlClCLASTlCS ;’ lNTERKJR BASlll Fig. 2. Paleogeography of the Elk Point basin, Keg River time (after Nelson, 1970; Campbell, 1987), such expressions as the Sluw PoindK~g Kiev interval pre-Devonian tectonism and erosion. Structural highs, such refer to the interval between the two named tops, unless the as those beneath the 3-l I and 3-5 wells (Figures 6 and 7) word inclusive is added, in which cast the lower unit is are prevalent throughout the Panny area. Generally, such also to be included in the interval. The maps OS the Panny structures are mapped by seismic data as being areally and Trout areas (Figures 4 and 5) show the locations of the closed rather than as lineaments, a pattern which is consis- wells incorporated in the geologic cross-sections and the tent both with the notion of an erosional surface and with approximate locations of the example seismic lines used as that of later (post-Devonian) faulting on conjugate sets of templates in this paper. In the following discussions, plants. As shown for out examples (Figures 6 and 7). the emphasis is placed on those geologic features which are basal Paleozoic elastics and Keg River sediments thin sig- pertinent to the interpretation of the example seismic data. nificantly from off-structure to on-structure. This is consis- tent with the idea that the Precambrian relief is essentially unchanged since the Early Devonian and that drape of PANNY FIELD overlying formations is a result of differential compaction. Interpretation of the geologic cross-section However, there is evidence, both geological (Cant, 1988) Two of the four wells incorporated into the structural and geophysical (P.C. Starnino, pers. comm.) of renewed geologic cross-sections, I-3.96.6W5 and 3-1 I-96-hW5 faulting since Keg River time (Middle Devonian), either on (Figure 6, line I), drilled in 1983 and 1984, respectively, new surfaces or as reactivation of former faults. Many currently produce oil from the Keg River Formation. The casts have been observed on seismic data where Devonian other wells, 3.S-96.6W5 and 4.5.Yb-6W5 (Figure 7, line sediments thicken over Precambrian structural highs, pre- 2), were drilled in 1984 and abandoned. Log suites for sumably us a result of reactivation of faults which then each of these wells are shown in Figures 6 and 7. could have served as conduits for waters which, in places, Structural relief between the wells has been inferred from have leached out quantities of salt (P.C. Starnino, pas. the seismic data. comm.). It may well be that different tectonic and sedimen- The deepest horizon identified on the cross-section is the tary effects have dominated in different parts of this extcn- Precambrian. As illustrated (Figure 8). this is a surface of sive area (Figure 3). This is a fertile area for future considerable relief, typically up to 100 m, as a result ot research. Formation in the 3-S and 4-5 wells is 4 and 45 m thick, respectively (Figure 7), while the Precambrian in the 3-5 well is XI m structurally higher than in the 4-5 well. In addition, the top of the Keg River Formation in the 3-S well is 41 m higher than in the 4-5 well and structurally closed. Argillaceous carbonates tend to predominate in the lower Keg River Formation while cleaner carbonates are predominant in the upper part (Figures 6 and 7). Typically, these upper carbonates are productive where they are stmc- turally closed over the underlying Precambrian, such as in the l-3 and 3-l I wells (Figure 6). As rvidcnced by these two wells, argillaceous carbonates are generally absent where the Precambrian is anomalously high.

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