CHAPTER 3 BEAVERHILL LAKE GROUP CARBONATE RESERVOIRS Ruth M. Ferry, Total Petroleum Canada Ltd. 'i"- ", 120 118 INTRODUCTION i I----r---~ 114 112 110' ~~~:~~! ---1---~---1 prevailing before the main transgressive phase of late-middle Point Fm surrounding the Peace River arch are discussed in detail by I Devonian. Limestones of the Slave Point and Swan Hills formations Craig (1987). Reservoirs of the Beaverhill Lake Group comprise Swan Hills Fm I represent the organic sedimentation phase of the widespread .!'I Ei.zl +59 CLARKE LAKE 1 ~II 5i ~I Beaverhill Lake transgression. Cessation of carbonate production and Slave Point Fm carbonates. The geographic locations of 9 ~ 9, Reservoirs of the Beaverhill Lake Group developed within Swan reservoirs discussed in this chapter are illustrated in Figure 3.1. t 0:1 I :II coincided with the influx of terrigenous material of the Waterways Hills Fm fringing-reef, isolated bioherms and reef-fringed carbonate !BR/TISH Ji ~ 1 ~, ! Fm associated with continued subsidence of the basin. Slave Point yOLUMBIAJ ~I , bank; Slave Point Fm barrier-reef, platform reefs, shoals and ALBERTA §I1 Hydrocarbon potential of the Beaverhill Lake Group was first I ' II I l.L. sedimentation was a diachronous event, the product of shallow water carbonate banks. The limestone framework of Swan Hills carbonates I I I 1 exploited in 1957, with the discovery of the Virginia Hills reef T deposition of an advancing marine environment. Stratigraphically, is preserved, whereas some Slave Point reservoirs are enhanced by I ' I •• SAWN fKE r complex in the Swan Hills area of westcentral Alberta. Fong (1959) the Slave Point Fm is correlative with the Swan Hills and Waterways dolomitization (e.g. Clarke Lake, Slave). Porous carbonates are introduced the term Swan Hills Member for the reefal carbonates I PEACk RIVER : •• SLAVE I' ! formations (Fig. 3.2). On a more regional scale, Griffin (1965) sealed by the enveloping argillaceous sediments of the Waterways i AfCH' •• GIFT I ascribed to the Beaverhill Lake Fm. Nearly ten years later, after the established the correlation between the Slave Point Fm in Fm (Horn River and Muskwa formations in British Columbia). r ~NIPE LAKE I \ Swan Hills play evolved into twelve major oil and two gas fields, J \.Il HOUSE MOUNTAIN I northeastern British Columbia and a substantial part of the Beaverhill Lake Group hydrocarbon traps often exhibit both ~. SWAN Hlll.S -C POOL t Leavitt and Fischbuch (1968) described the carbonates as Swan Hills 55 Waterways Fm in Alberta «Fig. 3.43) modified after Griffin, 1965). ~"-'-. I I\:I! I stratigraphic and structural components. Regional dip influences the Fm and raised the Beaverhill Lake to group status. Contem­ " I II GOOSE RIVER II I distribution of hydrocarbons within stratigraphic traps such as '" I SWAN HILLS!, , '- I REEFS , I poraneous with the Swan Hills oil boom, significant gas reserves ,~I Swan Hills Fm reefs developed in an embayment south of the carbonate banks (e.g. Ante Creek), shelf edges (e.g. Sawn Lake) and "",,1 \. I I, I were discovered in the Slave Point Fm in northeastern British 'j '- II - • EDMONTON I Peace River Arch (Figs. 3.1 and 3.4); platform, isolated bioherms some isolated reefs (e.g. Snipe Lake, Virginia Hills); hydrocarbons \.I' I l Columbia. Clarke Lake was the first in a series of major gas fields '1, ' t 53 and limestone bank facies are represented. Fischbuch (1968) divided being confined to the up-dip edge of these build-ups. Relief of the ) ,I I the Swan Hills Fm into nine informal units, corresponding to developed along the dolornitized barrier-reef system. The last 20 '.1', I reservoir may be affected by Precambrian topography, imposing a years of exploration have reaffirmed the economic significance of ,- , distinct phases of reef growth. The stratigraphic nomenclature (Fig. structural constraint on some stratigraphic traps (e.g. Gift) due to the Beaverhill Lake Group, with substantial oil reserves discovered \.r\ ! 3.3) used in this study follows Fischbuch (1968) and Hemphill et al. compaction-induced drape. Paleostructural influence on the in the Slave Point Fm, surrounding the Peace River Arch, Alberta. \, I, (1970). Conditions conducive to organic reef development were carbonate facies distribution exemplifies the mutual involvement of Total initial volume of hydrocarbons in place within Alberta is '~ S probably initiated on widespread topographic highs. Jansa and t ! structure and stratigraphy (e.g. Slave, Gift). estimated to be 941.4 x 106 m3 of oil and 385.94 x 109 m3 of gas. ''\ I Fischbuch (1974) suggested these highs were related to the 3 , , Estimated total recoverable reserves are 384.9 x 106 m of oil and \ I paleo-topographic configuration of the underlying Gilwood delta The eight Beaverhill Lake fields discussed in this chapter (Fig. 162.247 x 109 m3 of marketable gas. i, i complex. Paleotopography of the diachronous carbonate platform, 3.1) include reservoirs within the Swan Hills reef-fringed carbonate \I 1 '-L L~ surrounding the Peace River Arch, affected the facies distribution of bank (Ante Creek), isolated bioherms (Goose River, Snipe Lake), The Beaverhill Lake Group includes Fort Vermilion, Slave Point, the Slave Point Fm. Platform reefs and shoals were influenced by platform fringing-reef (House Mountain); Slave Point platform Swan Hills and Waterways formations. Fort Vermilion Fm evap­ Figure 3.1 Regional setting of the Beaverhill Lake Group fields structural highs on the carbonate shelf, often associated with (Gift, Slave), carbonate shelf and platform accretions (Sawn Lake) orites were deposited during regressive or oscillatory conditions discussed in this chapter. Precambrian topography. Depositional environments of the Slave and barrier-reef complex (Clarke Lake). The aforementioned 67 Caicarcou;, L"cc:s '1:0 111e Ireton Fnl ",halt"., general.;: an acoustic well, Atlantic Ante Creek 4-7-65-23W5, was cocnpleced November The Swan Hills Frn <Ji '\nte Creek is part of a massive I 1.- . ,"I 3 reI!t'ction.c, . annotatec {)(\ tde appropnatc eXainpl~~S as reton 1962 with initi<JI potential flow of 18 m /d<JY of 4".6° API gravity reef-fringed carbonate h~!nk which include'; Kayhob South and marker". It should IY' noted that the term is usee! generically and Ihe oil. Carson Creek (Fig. 3.4). The reservoir comprises porous limestone nldrkers are not nc(eS'arily stratigraphically correlative. reef, surrounding the c;e"'mate bank complex. Production is Str<Jtigr<Jphy of the Beaverhill Lake Group in tIle vicinity of Ante confined to the up-dip edge of the fringing-reef. In this study, the Creek is consistent with Figure 3.3, excepting thc Fort Vermilion Fm term "reef" or "bioherm" will be used when refering to the ANTE CREEK which is poorly defined. Corneil (1969) referred to the 3 m of fringing-reef <Jssociated \\ [[h the c<Jrbonate b<Jnk complex. Ante anhydritic shale, overlying the Elk Point cl<Jstics, as basal Beaverhill Creek field is <In elonga\c fe<Jture, <Jpproximately 12 km in length, INTRODUCTION L<Jke r<Jther than Fort Vermilion Fm. The Swan Hills Fm comprises isol<Jted from Ante Creek :'-Iorthwest by a surge channel (Fig. 3.4). a lower 20 m of Dmk Brown platform member overlain by up to 60 The reef complex is separated from the K<Jybob - Goose River ­ Ante Creek field of westcentral Alberta is located approximately m of the Light Brown biohermal unit. Argill<Jceous limestones and Snipe Lake reef chain by a deep embayment, filled with basinal 280 km northwest of Edmonton in Township 65, Ranges 23-24 W5M sh<Jles of the Waterw<Jys Fm envelop the SW<Jn Hills reef complex. sediments of the W<Jterways Fm. Ante Creek <Jnd Ante Creek (Fig. 3.1). Hydrocarbon production is from the Swan Hills Fm of Northwest <Jre the most westerly situated SW<Jn Hills reefs <Jnd the Beaverhill Lake Group, at 3435 m aver<Jge depth. The discovery FONG FISCHBUCH HEMPHILL et al 111'30' WATERWAYS Figure 3.2 Stratigraphy of the Beaverhill Lake Group, Peace River (1959) (1968) (1970) N Arch and Swan Hills regions. UPPER BASIN WATERWAYS WATERWAYS o, 2, BEAVERHILL -6- km. FORMATION FORMATION LAKE Z 0 x HOUSE MOUNTAIN I 0... f--' 0... SNIPE LAKE - SWAN HILLS 'C' POOL f- ::J ::J reservoirs are stratigraphically diverse, due to the time transgressive .::( Z - Z 0: LIGHT 0 > 0 z a: nature of the carbonate facies (Figs. 3.2 and 3.43). ~ 0 f-- 0 w 5440' w a: l- a: I- s: aJ ANTE CREEK a: CD I c.? <X: > c.? <X: 0 :::;; NORTHWEST 0 ::2: f----- a: w SWAN HILLS This chapter provides an integrated geologieal-geophysical W BROWN W ::2: - W ::2: aJ :::;; u.. ~ 0: ~ 0: approach to the interpretation of an exemplary eross-section through ::2: > e- lL ..p..",.,t-SWAN HILLS PLATFORM W I .::( 0 f----- .::( 0 I w ~ (f) LL LL C5 each field. Each morphologically distinet reservoir generates a -l -l I w .::( -l (f) > (f) ::J a: /*+...;,-:,+-SWAN HILLS -l UNIT rn -l eharaeteristie seismic signature for which an integrated analysis is -l -l -l f-- -l SOUTH " I -l -l 2: -l -l presented. Reservoir charaeteristics, including morphology, facies, -l 2: I I 0 I I porosity and eompaetion-induced drape are correlative with the -l I Z -. ).+~r--JUDYCREEK I <X: f-------- a: - a: f--_._-- I z - z seismic image. The lateral facies change between reservoir and s w <X: W <X: DARK a: (f) DARK - ~. encompassing sedimentary seetion is seismically defined, together ,.::(> S > S '." < i,): ,.". w I - .::( BROWN "" .-. ';:. _.',:',:',:, ," : '0 : (f) (f) ~++''..,-'r+CARSON BROWN W CREEK ; ":i,( with the influence of tectonic aetivity. Geologicaily significant > W f----- (PLATFORM) , ...- '; .::( CO CO I eomponents of the seismie response include isoehron changes, W I UNIT - MEMBER REEF FRINGED CO .- .' ' ·t::- (.<,.", ':""'>.'.