Pub Date : 2017-03-01DOI: 10.2113/GSCPGBULL.65.1.115
James Walker, I. Almasi, F. Stoakes, K. Potma, J. O'Keefe
The Athabasca Oil Sands, located in northeast Alberta, largely comprise a stacked succession of Early Cretaceous fluvial and marine sediments that were deposited directly above Middle and Late Devonian limestones, dolostones, calcareous shales and evaporites. Dissolution of halite and anhydrite from the Prairie Evaporite Formation by hypogenic karstification has resulted in the diachronous subsidence of overlying stratigraphic units and severe brecciation of important aquitards. These aquitards are required to protect oil sands mining operations from in-pit influxes of saline water sourced from Devonian aquifers. Sequence stratigraphic, palynologic and groundwater isotopic evidence suggests that karstification began prior to the Early Cretaceous, was active during deposition of the McMurray Formation and is still ongoing today in the Athabasca Oil Sands mining area. Groundwater flow associated with hypogenic karstification has important implications for the development of the Athabasca Oil Sands. For in-situ projects, Devonian aquifers are considered both as a resource for the moderately saline water required for steam generation and as a disposal zone for waste water. In open-pit oil sands mines, some of the most effective aquitards are removed by mining operations, thereby increasing the possibility that saline water from the Devonian aquifers could enter the mine pits. This poses safety, environmental and economic risks to mining operations that require a thorough understanding of the geologic, hydraulic and geomechanical controls related to hypogenic karstification. This paper, presents our current understanding of the hypogenic karst system in the vicinity of the Kearl mine.
{"title":"Hypogenic karst beneath the Athabasca Oil Sands: Implications for oil sands mining operations","authors":"James Walker, I. Almasi, F. Stoakes, K. Potma, J. O'Keefe","doi":"10.2113/GSCPGBULL.65.1.115","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.65.1.115","url":null,"abstract":"The Athabasca Oil Sands, located in northeast Alberta, largely comprise a stacked succession of Early Cretaceous fluvial and marine sediments that were deposited directly above Middle and Late Devonian limestones, dolostones, calcareous shales and evaporites. Dissolution of halite and anhydrite from the Prairie Evaporite Formation by hypogenic karstification has resulted in the diachronous subsidence of overlying stratigraphic units and severe brecciation of important aquitards. These aquitards are required to protect oil sands mining operations from in-pit influxes of saline water sourced from Devonian aquifers. Sequence stratigraphic, palynologic and groundwater isotopic evidence suggests that karstification began prior to the Early Cretaceous, was active during deposition of the McMurray Formation and is still ongoing today in the Athabasca Oil Sands mining area.\u0000\u0000Groundwater flow associated with hypogenic karstification has important implications for the development of the Athabasca Oil Sands. For in-situ projects, Devonian aquifers are considered both as a resource for the moderately saline water required for steam generation and as a disposal zone for waste water. In open-pit oil sands mines, some of the most effective aquitards are removed by mining operations, thereby increasing the possibility that saline water from the Devonian aquifers could enter the mine pits. This poses safety, environmental and economic risks to mining operations that require a thorough understanding of the geologic, hydraulic and geomechanical controls related to hypogenic karstification. This paper, presents our current understanding of the hypogenic karst system in the vicinity of the Kearl mine.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":"65 1","pages":"115-146"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.65.1.115","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43960064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-01DOI: 10.2113/GSCPGBULL.65.1.200
P. Broughton, D. Cotterill
Abstract The Middle Devonian hypogene evaporite dissolution, karst collapse resulted in the fragmentation of the Upper Devonian strata into a mosaic of differentially subsided fault blocks underlying the northern area of the Athabasca Oil Sands Deposit. Regional salt dissolution collapse developed structural troughs up to 50 km long on the sub-Cretaceous unconformity. The structural depressions formed above collapsed collinearly aligned, brine-filled, evaporite dissolution chimneys extending up to 100 m high within the Prairie Evaporite salt beds. Individual and coalesced arrays of dissolution chimneys developed along fault lineament dissolution trends that dissected the 10 km wide Prairie Evaporite salt scarp. 3D seismic images of chimney collapse structures in the Middle Devonian evaporite basin depocenter across central Saskatchewan are analogues used to interpret collapse structures evident in the Upper Devonian succession and the overlying Lower Cretaceous McMurray Formation. The Devonian-Cretaceous fault bound blocks located above the dissolution chimneys were gravity driven collapse structures. These structures included oblique rotational trajectories during the descents towards and into underlying dissolution voids. Breccia pipes were impinged along the deeper reaches of the inter-block fault planes as adjacent blocks obliquely rotated apart and towards each other, resulting in zones with compressional and extensional bed deformations during the variable but often rapid rates of vertical descent. The breccia pipes pass upward, along fault planes, into oblique shear zones with twisted beds and zigzag suture welding between adjacent blocks. Upper reaches of the collision zone, between adjacent blocks, were dominated by compressional deformations that resulted in sinkhole development bound on one side by the fault plane. Continued bed compression deformed and fragmented many sinkhole structures. Some of these collapse-induced fault block collisions suggest cataclysmic events, and caused seismicity triggered fluidization in the upper intervals of breccia pipes with mobilization as debris flows that spread across adjacent fault block surfaces.
{"title":"Breccia pipe and sinkhole linked fluidized beds and debris flows in the Athabasca Oil Sands: dynamics of evaporite karst collapse-induced fault block collisions","authors":"P. Broughton, D. Cotterill","doi":"10.2113/GSCPGBULL.65.1.200","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.65.1.200","url":null,"abstract":"Abstract The Middle Devonian hypogene evaporite dissolution, karst collapse resulted in the fragmentation of the Upper Devonian strata into a mosaic of differentially subsided fault blocks underlying the northern area of the Athabasca Oil Sands Deposit. Regional salt dissolution collapse developed structural troughs up to 50 km long on the sub-Cretaceous unconformity. The structural depressions formed above collapsed collinearly aligned, brine-filled, evaporite dissolution chimneys extending up to 100 m high within the Prairie Evaporite salt beds. Individual and coalesced arrays of dissolution chimneys developed along fault lineament dissolution trends that dissected the 10 km wide Prairie Evaporite salt scarp. 3D seismic images of chimney collapse structures in the Middle Devonian evaporite basin depocenter across central Saskatchewan are analogues used to interpret collapse structures evident in the Upper Devonian succession and the overlying Lower Cretaceous McMurray Formation. The Devonian-Cretaceous fault bound blocks located above the dissolution chimneys were gravity driven collapse structures. These structures included oblique rotational trajectories during the descents towards and into underlying dissolution voids. Breccia pipes were impinged along the deeper reaches of the inter-block fault planes as adjacent blocks obliquely rotated apart and towards each other, resulting in zones with compressional and extensional bed deformations during the variable but often rapid rates of vertical descent. The breccia pipes pass upward, along fault planes, into oblique shear zones with twisted beds and zigzag suture welding between adjacent blocks. Upper reaches of the collision zone, between adjacent blocks, were dominated by compressional deformations that resulted in sinkhole development bound on one side by the fault plane. Continued bed compression deformed and fragmented many sinkhole structures. Some of these collapse-induced fault block collisions suggest cataclysmic events, and caused seismicity triggered fluidization in the upper intervals of breccia pipes with mobilization as debris flows that spread across adjacent fault block surfaces.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":"65 1","pages":"200-234"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.65.1.200","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46296936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-01DOI: 10.2113/GSCPGBULL.65.1.5
Michael B. Rogers
Northeast Alberta is the location of one of the world’s largest petroleum deposits, the Athabasca Oil Sands, hosted in Lower Cretaceous McMurray Formation sandstones. The McMurray Formation was deposited on a deeply eroded Upper Devonian unconformity surface that was strongly influenced by underlying carbonate and evaporite units. Development of the oil sands has resulted in a significant increase in new data related to the underlying Devonian of northeast Alberta. In particular, the requirement for deep disposal of water has resulted in a number of wells being drilled into and through the porous dolomites of the Middle Devonian Keg River Formation that is a few hundred metres below the McMurray bitumen deposits. In addition, the acquisition of large areas of high-resolution 3D seismic data to assist the delineation and development of the oil sands reserves has provided powerful insights into the depositional patterns and later dissolutive geometries of the underlying carbonate and evaporite deposits. The Keg River and overlying Prairie Evaporite formations that are the focus of this paper were deposited in the intracratonic Elk Point Basin that covered most of the area now delineated by the Western Canada Sedimentary Basin. These units and their lateral equivalents have been extensively studied in Saskatchewan, northwest Alberta, southern Northwest Territories and northeast British Columbia. In contrast, the two formations have been lightly studied and rarely published upon in northeast Alberta. The current detailed study of several areas with abundant new data, combined with a review of the regional dataset in northeast Alberta has provided new insights into the geology of these units. A revised stratigraphy for the two formations is presented which includes the formal definition of the proposed Aurora Member, a significant anhydrite unit within the Prairie Evaporite Formation that was previously included as a sub-unit of the Whitkow Member. The Keg River Formation is divided into the Lower and Upper Keg River members. The Lower Keg River Member is a thin, regionally consistent unit composed of an upward deepening transgressive systems tract. In most places, the Lower Keg River is overlain by the Upper Keg River Member which has two distinct facies. At the base is a widespread shallowing upwards microbial oncolitic facies, here referred to as the Keg River Ramp, which provided the foundation for more aerially restricted overlying deposits of shallow water carbonate. On the edge of the basin, a Basin Margin Platform formed and prograded out over the Keg River Ramp. In the centre of the basin, biogenic build-ups developed. Integrated interpretation of the seismic with the wells shows that the build-ups often have well established but aerially restricted reef margins of frame-building organisms. However, the bulk of these build-ups consist of loosely consolidated peloidal grainstones and packstones. A drop in sea level in conjunction with the deve
{"title":"Stratigraphy of the Middle Devonian Keg River and Prairie Evaporite formations, northeast Alberta, Canada","authors":"Michael B. Rogers","doi":"10.2113/GSCPGBULL.65.1.5","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.65.1.5","url":null,"abstract":"Northeast Alberta is the location of one of the world’s largest petroleum deposits, the Athabasca Oil Sands, hosted in Lower Cretaceous McMurray Formation sandstones. The McMurray Formation was deposited on a deeply eroded Upper Devonian unconformity surface that was strongly influenced by underlying carbonate and evaporite units. Development of the oil sands has resulted in a significant increase in new data related to the underlying Devonian of northeast Alberta. In particular, the requirement for deep disposal of water has resulted in a number of wells being drilled into and through the porous dolomites of the Middle Devonian Keg River Formation that is a few hundred metres below the McMurray bitumen deposits. In addition, the acquisition of large areas of high-resolution 3D seismic data to assist the delineation and development of the oil sands reserves has provided powerful insights into the depositional patterns and later dissolutive geometries of the underlying carbonate and evaporite deposits. The Keg River and overlying Prairie Evaporite formations that are the focus of this paper were deposited in the intracratonic Elk Point Basin that covered most of the area now delineated by the Western Canada Sedimentary Basin. These units and their lateral equivalents have been extensively studied in Saskatchewan, northwest Alberta, southern Northwest Territories and northeast British Columbia. In contrast, the two formations have been lightly studied and rarely published upon in northeast Alberta. The current detailed study of several areas with abundant new data, combined with a review of the regional dataset in northeast Alberta has provided new insights into the geology of these units. A revised stratigraphy for the two formations is presented which includes the formal definition of the proposed Aurora Member, a significant anhydrite unit within the Prairie Evaporite Formation that was previously included as a sub-unit of the Whitkow Member. The Keg River Formation is divided into the Lower and Upper Keg River members. The Lower Keg River Member is a thin, regionally consistent unit composed of an upward deepening transgressive systems tract. In most places, the Lower Keg River is overlain by the Upper Keg River Member which has two distinct facies. At the base is a widespread shallowing upwards microbial oncolitic facies, here referred to as the Keg River Ramp, which provided the foundation for more aerially restricted overlying deposits of shallow water carbonate. On the edge of the basin, a Basin Margin Platform formed and prograded out over the Keg River Ramp. In the centre of the basin, biogenic build-ups developed. Integrated interpretation of the seismic with the wells shows that the build-ups often have well established but aerially restricted reef margins of frame-building organisms. However, the bulk of these build-ups consist of loosely consolidated peloidal grainstones and packstones. A drop in sea level in conjunction with the deve","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":"65 1","pages":"5-63"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.65.1.5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48105431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-01DOI: 10.2113/GSCPGBULL.65.1.1
C. Schneider, D. Cotterill
Devonian strata beneath the oil sands have been acknowledged and studied since the early explorers of the 1800s. The focus on the Devonian shifted from the original emphasis on correlation and age, to evaporite resources in the early to mid-1900s, to stratigraphy of the oil sands underburden in the 1950s and 1960s, and finally to the current emphasis on geohazards and disposal. Devonian and later strata in the oil sands mining area have been impacted by the dissolution of the Prairie Evaporite Formation, a 200+ m thick succession of mostly halite. This special issue on “The Devonian beneath the Oil Sands” presents some of the current research and sets a baseline for future investigation.
{"title":"Introduction: The Devonian beneath the oil sands","authors":"C. Schneider, D. Cotterill","doi":"10.2113/GSCPGBULL.65.1.1","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.65.1.1","url":null,"abstract":"Devonian strata beneath the oil sands have been acknowledged and studied since the early explorers of the 1800s. The focus on the Devonian shifted from the original emphasis on correlation and age, to evaporite resources in the early to mid-1900s, to stratigraphy of the oil sands underburden in the 1950s and 1960s, and finally to the current emphasis on geohazards and disposal. Devonian and later strata in the oil sands mining area have been impacted by the dissolution of the Prairie Evaporite Formation, a 200+ m thick succession of mostly halite. This special issue on “The Devonian beneath the Oil Sands” presents some of the current research and sets a baseline for future investigation.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":"65 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.65.1.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41641717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-01DOI: 10.2113/GSCPGBULL.65.1.175
M. Barton, I. Porter, C. O’Byrne, R. Mahood
Abstract The Cretaceous McMurray Formation in NE Alberta contains nearly a trillion barrels of bitumen, a significant portion of which is being developed via surface mining and in-situ thermal methods. The focus of this report is the structure and stratigraphy of the Cretaceous McMurray Formation and its relationship to the configuration of the underlying Devonian section in the area of Shell Canada’s Albian Sands Lease (Township 95, ranges 9 and R10W4M), a joint oil sands mining venture between Shell Canada (60%), Chevron Canada Limited (20%) and Marathon Oil Canada Corporation (20%). The structural and stratigraphic relationships between the two intervals has been the source of several recent investigations due to industry related incidents that demonstrated the integrity of the underlying Devonian succession can be compromised by vertical pathways associated with faults, sinkholes, or other features. Key findings of this work include the following: The present morphology of the Pre-Cretaceous unconformity is primarily due to structural deformation (differential subsidence) related to dissolution and collapse of the underlying Prairie Evaporite Formation and overlying Devonian units of the Beaverhill Lake Group rather than erosion relief. Two types of collapse structures are recognized: a) large scale sag folds that are 1-to-10 kilometres in extent; and b) small scale breccia pipes that are 10- to-100 metres in diameter. The sag folds are interpreted to have formed in response to the dissolution of halite. The breccia pipes, which postdate the sag folds, represent sinkhole features that formed in response to the dissolution of gypsum. Rather than onlapping the unconformity, Lower McMurray strata thin and converge across structural highs and thicken and diverge across structural lows, demonstrating much of the dissolution driven subsidence was contemporaneous with the deposition. The subsidence produced up to 80 metres of accommodation and involved the coherent sagging and faulting of large intact segments of the underlying Devonian section. The arrangement of major stratigraphic packages indicates subsidence features shifted locations through time rather than persisting through the entire Lower McMurray. Changes in sedimentation style between sand-rich fluvial packages to mud-rich lacustrine dominated packages within the lower McMurray reflect changes in relative rates of subsidence. Sand-rich fluvial units are localized in settings with low-to-moderate subsidence rates, while mud-rich fluvial-lacustrine units are localized in settings with moderate-to-high subsidence rates. The Middle-to-Upper McMurray section is composed of four high relief unconformity bound units that display flat/horizontal stratal relationships with the underlying structure of the Pre Cretaceous unconformity. In contrast to the Lower McMurray, stratigraphic relationships indicate it was largely impacted by falls and rises in relative sea-level (cycles of negative and posi
{"title":"Impact of the Prairie Evaporite Dissolution Collapse on McMurray Stratigraphy and Depositional Patterns, Shell Albian Sands Lease 13, Northeast Alberta","authors":"M. Barton, I. Porter, C. O’Byrne, R. Mahood","doi":"10.2113/GSCPGBULL.65.1.175","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.65.1.175","url":null,"abstract":"Abstract The Cretaceous McMurray Formation in NE Alberta contains nearly a trillion barrels of bitumen, a significant portion of which is being developed via surface mining and in-situ thermal methods. The focus of this report is the structure and stratigraphy of the Cretaceous McMurray Formation and its relationship to the configuration of the underlying Devonian section in the area of Shell Canada’s Albian Sands Lease (Township 95, ranges 9 and R10W4M), a joint oil sands mining venture between Shell Canada (60%), Chevron Canada Limited (20%) and Marathon Oil Canada Corporation (20%). The structural and stratigraphic relationships between the two intervals has been the source of several recent investigations due to industry related incidents that demonstrated the integrity of the underlying Devonian succession can be compromised by vertical pathways associated with faults, sinkholes, or other features. Key findings of this work include the following: The present morphology of the Pre-Cretaceous unconformity is primarily due to structural deformation (differential subsidence) related to dissolution and collapse of the underlying Prairie Evaporite Formation and overlying Devonian units of the Beaverhill Lake Group rather than erosion relief. Two types of collapse structures are recognized: a) large scale sag folds that are 1-to-10 kilometres in extent; and b) small scale breccia pipes that are 10- to-100 metres in diameter. The sag folds are interpreted to have formed in response to the dissolution of halite. The breccia pipes, which postdate the sag folds, represent sinkhole features that formed in response to the dissolution of gypsum. Rather than onlapping the unconformity, Lower McMurray strata thin and converge across structural highs and thicken and diverge across structural lows, demonstrating much of the dissolution driven subsidence was contemporaneous with the deposition. The subsidence produced up to 80 metres of accommodation and involved the coherent sagging and faulting of large intact segments of the underlying Devonian section. The arrangement of major stratigraphic packages indicates subsidence features shifted locations through time rather than persisting through the entire Lower McMurray. Changes in sedimentation style between sand-rich fluvial packages to mud-rich lacustrine dominated packages within the lower McMurray reflect changes in relative rates of subsidence. Sand-rich fluvial units are localized in settings with low-to-moderate subsidence rates, while mud-rich fluvial-lacustrine units are localized in settings with moderate-to-high subsidence rates. The Middle-to-Upper McMurray section is composed of four high relief unconformity bound units that display flat/horizontal stratal relationships with the underlying structure of the Pre Cretaceous unconformity. In contrast to the Lower McMurray, stratigraphic relationships indicate it was largely impacted by falls and rises in relative sea-level (cycles of negative and posi","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":"65 1","pages":"175-199"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44094244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-01DOI: 10.2113/GSCPGBULL.65.1.147
C. Schneider, M. Grobe
Abstract Elk Point Group outcrops in the Athabasca Oil Sands mining region (AOSMR) and adjacent areas include exposures of the La Loche, Contact Rapids, Keg River, and Prairie Evaporite formations. Here, we review prior investigations of these formations in outcrop, followed by new descriptions of some outcrops, including those previously unpublished or newly discovered. The fluvial to marginal marine sandstone and conglomerate of the La Loche Formation, informally known as the granite wash, outcrops along the Clearwater River in Saskatchewan, where it is sandwiched between the Precambrian basement and the Contact Rapids Formation. In Alberta, the La Loche Formation is exposed at a locality along Whitemud Falls, where it directly underlies the Keg River Formation as a lithic sandstone and fills paleokarst crevices in the Keg River dolostone. From these two outcrops we recognize three facies in the La Loche Formation: regolith, lithic conglomerate, and lithic to arkosic sandstone. The marginal marine shale, silt, and dolomite of the Contact Rapids Formation outcrops in Saskatchewan at its namesake Contact Rapids, but is exposed only as a slumped bank of grey to greenish mud. We examined Keg River Formation dolostone from three outcrops along the Clearwater River at Contact Rapids in Saskatchewan and Whitemud Falls and Cascade Rapids in Alberta. We also describe an outcrop on the Firebag River in Alberta. From these outcrops, we recognize three general facies: bedded to laminated cryptalgal dolomitized bindstone (originating from an intertidal paleoenvironment), coral and stromatoporoid-bearing dolomitized floatstone to rudstone (originally a reef), and crinoid and brachiopod dolomitized floatstone (from off-reef or inter-reef areas). A newly recognized outcrop of the collapse residue from the dissolved Prairie Evaporite Formation occurs along the Clearwater River, where cobbles and boulders of breccia and other less soluble Prairie Evaporite rock weather out of the river bank between several sulfur springs.
{"title":"A review and new descriptions of Elk Point Group outcrops in the Athabasca Oil Sands mining region","authors":"C. Schneider, M. Grobe","doi":"10.2113/GSCPGBULL.65.1.147","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.65.1.147","url":null,"abstract":"Abstract Elk Point Group outcrops in the Athabasca Oil Sands mining region (AOSMR) and adjacent areas include exposures of the La Loche, Contact Rapids, Keg River, and Prairie Evaporite formations. Here, we review prior investigations of these formations in outcrop, followed by new descriptions of some outcrops, including those previously unpublished or newly discovered. The fluvial to marginal marine sandstone and conglomerate of the La Loche Formation, informally known as the granite wash, outcrops along the Clearwater River in Saskatchewan, where it is sandwiched between the Precambrian basement and the Contact Rapids Formation. In Alberta, the La Loche Formation is exposed at a locality along Whitemud Falls, where it directly underlies the Keg River Formation as a lithic sandstone and fills paleokarst crevices in the Keg River dolostone. From these two outcrops we recognize three facies in the La Loche Formation: regolith, lithic conglomerate, and lithic to arkosic sandstone. The marginal marine shale, silt, and dolomite of the Contact Rapids Formation outcrops in Saskatchewan at its namesake Contact Rapids, but is exposed only as a slumped bank of grey to greenish mud. We examined Keg River Formation dolostone from three outcrops along the Clearwater River at Contact Rapids in Saskatchewan and Whitemud Falls and Cascade Rapids in Alberta. We also describe an outcrop on the Firebag River in Alberta. From these outcrops, we recognize three general facies: bedded to laminated cryptalgal dolomitized bindstone (originating from an intertidal paleoenvironment), coral and stromatoporoid-bearing dolomitized floatstone to rudstone (originally a reef), and crinoid and brachiopod dolomitized floatstone (from off-reef or inter-reef areas). A newly recognized outcrop of the collapse residue from the dissolved Prairie Evaporite Formation occurs along the Clearwater River, where cobbles and boulders of breccia and other less soluble Prairie Evaporite rock weather out of the river bank between several sulfur springs.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":"65 1","pages":"147-174"},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.65.1.147","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44716587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-12-01DOI: 10.2113/GSCPGBULL.64.4.538
D. Herbers, R. MacNaughton, E. Timmer, M. Gingras
Abstract This study presents the first detailed sedimentological and ichnological study of the Cambrian Mount Clark Formation from the Colville Hills region of the Northwest Territories, Canada. Based on analyses of four industry drill cores, eight lithofacies are identified that occur in a recurring facies association. This facies association records a progradational storm-influenced shoreface succession preserving offshore to upper shoreface sedimentary environments. Storm influence is indicated by the presence of hummocky cross-stratification (HCS) and of tempestite/fair-weather couplets consisting of low-angle cross-bedded sandstone with thin bioturbated interbeds. Marine flooding surfaces are expressed as pebbly transgressive lags that separate near-shore and overlying offshore sedimentary environments. Piperock is common, represents the most oil stained lithology, and is preserved within a wave-dominated shoreface succession. The sedimentological and ichnological character of this succession suggests that predictable shoreface stacking patterns and sandstone distributions characterize the Mount Clark Formation in the subsurface of the study region.
{"title":"Sedimentology and ichnology of an Early-Middle Cambrian storm-influenced barred shoreface succession, Colville Hills, Northwest Territories","authors":"D. Herbers, R. MacNaughton, E. Timmer, M. Gingras","doi":"10.2113/GSCPGBULL.64.4.538","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.64.4.538","url":null,"abstract":"Abstract This study presents the first detailed sedimentological and ichnological study of the Cambrian Mount Clark Formation from the Colville Hills region of the Northwest Territories, Canada. Based on analyses of four industry drill cores, eight lithofacies are identified that occur in a recurring facies association. This facies association records a progradational storm-influenced shoreface succession preserving offshore to upper shoreface sedimentary environments. Storm influence is indicated by the presence of hummocky cross-stratification (HCS) and of tempestite/fair-weather couplets consisting of low-angle cross-bedded sandstone with thin bioturbated interbeds. Marine flooding surfaces are expressed as pebbly transgressive lags that separate near-shore and overlying offshore sedimentary environments. Piperock is common, represents the most oil stained lithology, and is preserved within a wave-dominated shoreface succession. The sedimentological and ichnological character of this succession suggests that predictable shoreface stacking patterns and sandstone distributions characterize the Mount Clark Formation in the subsurface of the study region.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":"5 1","pages":"538-554"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.64.4.538","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68210129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-12-01DOI: 10.2113/GSCPGBULL.64.4.516
V. Crombez, S. Rohais, F. Baudin, T. Euzen
This study illustrates a basin-scale sequence stratigraphic framework based on wireline well-logs, cores and outcrops from the Early Triassic Montney Formation in the Western Canada Sedimentary Basin. A very dense and well-constrained database (2200 wells, 18 cores and 4 outcrops) derived from petroleum exploration made it possible to implement and test common workflows and terminologies used for sequence stratigraphic analysis along an ancient wave-dominated margin. Following facies definition from cores and outcrops and recognition of associated well-log patterns, a two-step approach allows for the reconstruction of large-scale geometries: 1) the model-independent definition of surfaces and units; and 2) the interpretation of the sequence boundaries and systems tracts based on a depositional sequence model.The typical facies association and log pattern of different sedimentary environments including tidal, as well as wave-dominated foreshore, shoreface and offshore settings are presented. The spatial distribution of characteristic sedimentary environments associated with stratigraphic surfaces and systems tracts is also detailed at the basin scale. Among other results, this study highlights the differences in the sedimentary facies geometries across two different types of sequence boundaries: the facies geometries of the first sequence boundary are quite similar to Haq et al. (1988) sequence model, whereas the geometries of the second are similar to the Hunt and Tucker (1992) sequence model. This work shows that during a rapid, high amplitude base level fall on a high gradient slope, turbidites are more likely to occur, whereas, during slow, low amplitude base level fall on a low gradient topography, forced regressive shoreface will be more likely to occur.
{"title":"Facies, well-log patterns, geometries and sequence stratigraphy of a wave-dominated margin: insight from the Montney Formation (Alberta, British Columbia, Canada)","authors":"V. Crombez, S. Rohais, F. Baudin, T. Euzen","doi":"10.2113/GSCPGBULL.64.4.516","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.64.4.516","url":null,"abstract":"This study illustrates a basin-scale sequence stratigraphic framework based on wireline well-logs, cores and outcrops from the Early Triassic Montney Formation in the Western Canada Sedimentary Basin. A very dense and well-constrained database (2200 wells, 18 cores and 4 outcrops) derived from petroleum exploration made it possible to implement and test common workflows and terminologies used for sequence stratigraphic analysis along an ancient wave-dominated margin. Following facies definition from cores and outcrops and recognition of associated well-log patterns, a two-step approach allows for the reconstruction of large-scale geometries: 1) the model-independent definition of surfaces and units; and 2) the interpretation of the sequence boundaries and systems tracts based on a depositional sequence model.The typical facies association and log pattern of different sedimentary environments including tidal, as well as wave-dominated foreshore, shoreface and offshore settings are presented. The spatial distribution of characteristic sedimentary environments associated with stratigraphic surfaces and systems tracts is also detailed at the basin scale. Among other results, this study highlights the differences in the sedimentary facies geometries across two different types of sequence boundaries: the facies geometries of the first sequence boundary are quite similar to Haq et al. (1988) sequence model, whereas the geometries of the second are similar to the Hunt and Tucker (1992) sequence model. This work shows that during a rapid, high amplitude base level fall on a high gradient slope, turbidites are more likely to occur, whereas, during slow, low amplitude base level fall on a low gradient topography, forced regressive shoreface will be more likely to occur.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":"64 1","pages":"516-537"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.64.4.516","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68209869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-12-01DOI: 10.2113/GSCPGBULL.64.4.495
S. Pemberton, J. Maceachern, M. Gingras
On May 14th 2016, Canada lost one of its legends – Dr. Charles Richard Stelck, geologist, prospector, oil finder, explorer and, a teacher and mentor to thousands of students. It was in his role as an educator that Charlie attained his greatest satisfaction. Professor C.R. Stelck, a renowned Canadian Geologist, was known for his outstanding accomplishments in establishing the stratigraphy of the Western Canada Sedimentary Basin, as a foundational contributor to Alberta’s oil and gas industry, and most importantly as an educator at the University of Alberta. Widely known as Charlie, Professor Stelck was a teacher and mentor who guided thousands of men and women into Geology.
{"title":"An iconic professor: the life of Charles Richard Stelck O.C., Ph.D., F.R.S.C., P. Geol. (May 20, 1917–May 14, 2016)","authors":"S. Pemberton, J. Maceachern, M. Gingras","doi":"10.2113/GSCPGBULL.64.4.495","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.64.4.495","url":null,"abstract":"On May 14th 2016, Canada lost one of its legends – Dr. Charles Richard Stelck, geologist, prospector, oil finder, explorer and, a teacher and mentor to thousands of students. It was in his role as an educator that Charlie attained his greatest satisfaction. Professor C.R. Stelck, a renowned Canadian Geologist, was known for his outstanding accomplishments in establishing the stratigraphy of the Western Canada Sedimentary Basin, as a foundational contributor to Alberta’s oil and gas industry, and most importantly as an educator at the University of Alberta. Widely known as Charlie, Professor Stelck was a teacher and mentor who guided thousands of men and women into Geology.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":"64 1","pages":"495-515"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.64.4.495","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68210152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-12-01DOI: 10.2113/GSCPGBULL.64.4.477
E. Petrie, James P. Evans
In the brittle crust, the distribution of natural rock fractures and their failure modes are a function of rock strength and its interactions between overburden pressure, pore-fluid pressure, and tectonic loading. The characterization of variability in rock strength and the associated changes in subsurface strain distribution is especially important for modeling the response of low-permeability rocks to changes in effective stress. This paper documents the effect variations in elastic mechanical properties have on the nature and distribution of fractures in the subsurface. Outcrop and geophysical wireline log evaluation of the Jurassic Carmel Formation and Navajo Sandstone was used to identify mechano-stratigraphic units and model subsurface strain distribution within sedimentary successions and across sedimentary interfaces. Two finite element models were constructed and populated with elastic moduli derived from geophysical wireline data in order to understand where natural fractures form in rocks with varying layer thickness and elastic properties. Strain distribution results from a 3-layer and a 5-layer model are compared to the natural deformation response visible in outcrop. Model results show that more fractures are expected in high strain regions and fewer fractures in low strain regions. Strain variations are observed in both model scenarios and occur at material interfaces. The simple 3-layer model results in a smoothing of strain variations, while the 5-layer model captures strain variations that more closely match the fracture density observed in outcrop. Results from the 5-layer model suggests an interplay between Young’s modulus and Poisson’s ratio and that high strain regions form in thin (1-m thick) layers with moderate Young modulus (17.2 GPa) and Poisson ratio (0.26) values. Outcrop observations and modeling results indicate that the potential for subsurface failure and fluid flow would not be restricted to the low fracture strength units but can cut vertically across interfaces of varying mechanical strength. Results from this work indicates that these types of models can be used to identify stratigraphic layers that are more prone to mechanical failure or identify layers that have more natural fractures or are more likely to form induced fractures.
{"title":"Modeling strain across mechanical sedimentary lithologic interfaces: geomechanical models derived from outcrop analysis","authors":"E. Petrie, James P. Evans","doi":"10.2113/GSCPGBULL.64.4.477","DOIUrl":"https://doi.org/10.2113/GSCPGBULL.64.4.477","url":null,"abstract":"In the brittle crust, the distribution of natural rock fractures and their failure modes are a function of rock strength and its interactions between overburden pressure, pore-fluid pressure, and tectonic loading. The characterization of variability in rock strength and the associated changes in subsurface strain distribution is especially important for modeling the response of low-permeability rocks to changes in effective stress. This paper documents the effect variations in elastic mechanical properties have on the nature and distribution of fractures in the subsurface. Outcrop and geophysical wireline log evaluation of the Jurassic Carmel Formation and Navajo Sandstone was used to identify mechano-stratigraphic units and model subsurface strain distribution within sedimentary successions and across sedimentary interfaces. Two finite element models were constructed and populated with elastic moduli derived from geophysical wireline data in order to understand where natural fractures form in rocks with varying layer thickness and elastic properties. Strain distribution results from a 3-layer and a 5-layer model are compared to the natural deformation response visible in outcrop. Model results show that more fractures are expected in high strain regions and fewer fractures in low strain regions. Strain variations are observed in both model scenarios and occur at material interfaces. The simple 3-layer model results in a smoothing of strain variations, while the 5-layer model captures strain variations that more closely match the fracture density observed in outcrop. Results from the 5-layer model suggests an interplay between Young’s modulus and Poisson’s ratio and that high strain regions form in thin (1-m thick) layers with moderate Young modulus (17.2 GPa) and Poisson ratio (0.26) values. Outcrop observations and modeling results indicate that the potential for subsurface failure and fluid flow would not be restricted to the low fracture strength units but can cut vertically across interfaces of varying mechanical strength. Results from this work indicates that these types of models can be used to identify stratigraphic layers that are more prone to mechanical failure or identify layers that have more natural fractures or are more likely to form induced fractures.","PeriodicalId":56325,"journal":{"name":"Bullentin of Canadian Petroleum Geology","volume":"23 1","pages":"477-494"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2113/GSCPGBULL.64.4.477","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68210056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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