Browsing by Author "Hopkins, John C."
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Item Open Access Anatomy of a paleokarst reservoir: Sedimentation and diagenesis of the pekisko formation in Twining oil field, Alberta, Canada(1998) Reid, Susan J.; Hopkins, John C.Item Open Access Depositional systems of the Mississippian MC-3 (Alida beds), Pierson Field, Manitoba(1988) Olsen-Heise, Katrina Edith Desa; Hopkins, John C.Item Open Access High resolution sequence stratigraphy and a study of reservoir controls of the glauconitic sandstone member in the Cessford Mannville C Pool, Southeastern Alberta(2002) Lynch, Thérèse Kathleen; Hopkins, John C.Item Open Access High resolution sequence stratigraphy, sedimentology, petrology and reservoir potentials of the Glauconitic member in Westerose and adjacent fields, Alberta, Canada(2001) Okaro, Patrick Ifechukwu; Hopkins, John C.The Glauconitic member hosts significant gas reserves in an extensive northeastsouthwest trending marine complex informally known as the Hoadley barrier. The unit is studied in order to develop a high resolution sequence stratigraphic model and understand facies architecture, petrology and diagenetic pathways of this strata within a sequence stratigraphic framework. Six high frequency sequences are recognized (G 1, G2, G3, G4, G5 and G6) within the Glauconitic member in the study. These sequences are separated from one another by surfaces of incision or subaerial exposure which in locations are coincident with a flooding surface or transgressive surface of erosion. The sandstones of the G 1 sequence are very fine grained quartzarenites deposited in a storm-dominated shoreface. A transgressive systems tract (TST) as well as a highstand systems (HST) are recognizable in the G2 sequence. Within the HST, two parasequences (G2A and G2B) are recognized separated by a flooding surface. The G2A sandstones are very fine to fine-grained dolomite-rich litharenites deposited in a stormdominated shoreface. They are characterized by abundant dolomite cement and rarely develop reservoir quality porosity and permeability. The G2B sandstones are very to fine grained chert litharenites deposited in a strandplain storm-dominated system. These sandstones develop reservoir quality within the relatively quartz-rich foreshore facies. The G3 sequence is characterized by a TST consisting of estuarine and shoreface depositional systems. The overlying HST is a wave-dominated delta fed by shoreface coeval delta distributaries. G3 sandstones are fine to medium grained chert litharenites (shoreface) to sublitharenites (foreshore) and are excellent gas producers as a result of their coarser grain size and abundance of secondary porosity. Volcanic arenites and feldspar-rich litharenites are typical of the G4 sequence. Pluvial and estuarine incised valleys of the TST and coastal plain sediments of the HST characterize the G4. The sandstones are plugged with carbonate and clay cement and matrix and do not develop reservoir quality. The G5 and G6 sequences are recognized and mapped on the basis of the recognition of regional correlatable G4, G5 and G6 coals. These coals cap the various sequences and amalgamate, split and contain crevasse splays and channels in between them. The 06 channel is interpreted as being deposited in a large bedload channel with a tendency to erode its banks.Item Embargo Lithofacies analysis for the lower cretaceous glauconitic sandstone in the Medicine River area, central Alberta(1981) Reichenbach, Mary E.; Hopkins, John C.Item Open Access Paleozoic stromatactis and zebra carbonate mud-mounds: Global abundance and paleogeographic distribution(Geological Society of America, 2004-03) Krause, Federico F.; Scotese, Christopher R.; Nieto, Carlos; Sayegh, Selim' G.; Hopkins, John C.; Meyer, Rudolf 0.Item Open Access Penetrative calcretes and their stratigraphic implications: Comment and Reply(Geological Society of America, 1993-06) Hopkins, John C.; Krause, Federico F.Item Embargo Sedimentologic and diagenetic evolution of an ooidgrapestone shoal complex within the Caicos Bank(1990) Cairns, David J. (David Joseph); Hopkins, John C.Item Open Access Sedimentologic and diagenetic evolution of an ooidgrapestone shoal complex within the Caicos Bank interior, Turks and Caicos Islands, British West Indies(1990) Cairns, David J. (David Joseph); Hopkins, John C.Item Open Access Sedimentology and diagenesis of carbonate mud-dominated buildups: Lower Devonian of Hamar Laghdad, Eastern Anti-Atlas Mountains, Morocco, Africa(1995) Aitken, Steven Andrew; Hopkins, John C.Item Open Access Item Open Access Sedimentology and diagenesis of the Nisku formation, Wayne, Alberta(1998) Ford, Blake Harold; Hopkins, John C.Item Open Access Sedimentology and geologic history of the Upper Devonian (Frasnian) uppermost Ireton and Nisku Formations, Bashaw area, Alberta(1987) Gilhooly, Murray Gordon; Hopkins, John C.The Camrose Member of the Ireton Formation, and the Nisku Formation (Frasnian) of the subsurface of the Bashaw area, Alberta represent episodes of shallow water carbonate and evaporite sedimentation, influenced by antecedent topography of the underlying Leduc Formation Bashaw carbonate complex. Fifteen lithofacies can be discerned, and range environmentally from deep, open carbonate ramp settings, through ramp-platform transition tabular stromatoporoid-coral communities to restricted platform interior subaqueous to peritidal carbonates and evaporites. In addition, terrigenous elastic sediments become increasingly common in the upper part of the Nisku Formation. Two orders of cyclicity are present within the Camrose Member and Nisku Formation in the Bashaw area. The first is on the scale of greater than 10 m and consists of shallowing upwards sequences ranging from deeper ramp to peritidal carbonates and evaporites. These cycles are best expressed on the west and north side of the underlying Bashaw complex at the ramp-platform transition. Smaller scale cycles less than 5 m thick typify platform interior settings and range from restricted subtidal carbonates to peritidal carbonates and evaporites. Fluctuations in basin subsidence and eustatic sea level were the ultimate control on sedimentation in the Upper Frasnian of the Bashaw area, with carbonate sedimentation dominating during periods of rapid relative sea level rise, and terrigenous elastic sediments prograding into the area from northeastly sources during periods of lower relative sea level rise or stillstands in sea level. Autocyclic mechanisms, particularly in platform interior settings, exerted a strong control on observed cyclicity, and depend upon high sediment production and accumulation rates associated with shallow water carbonate sedimentation. The underlying Leduc Formation Bashaw complex exerted a strong control on sedimentation of the Camrose Member and Nisku Formation. North and west sides of the Bashaw complex acted as relict highs and localized tabular stromatoporoid communities during Camrose Member and Nisku Formation sedimentation. Growth of ramp-platform transition stromatoporoid communities acted to restrict circulation in a platformward direction, leading to establishment of locally complex restricted subtidal to peritidal environments. Camrose Member and Nisku Formation sediments can be traced regionally westward through the Leduc area and to the West Pembina area, where downslope 'pinnacle' reefs comprised of Disphyllid corals and tabular stromatoporoids occur, and are time equivalent to Nisku Formation ramp and platform sediments in the Bashaw area.Item Open Access Sedimentology and paragenetic evolution of Mississippian Pekisko Formation, Minnehik-Buck Lake Field and adjacent area, Alberta, Canada(2001) Fattahi, Shadi; Hopkins, John C.Item Embargo Sedimentology of the Middle Jurassic Rock Creek Member in the subsurface of west-central Alberta(1982) Marion, Donat J.; Hopkins, John C.Quartzarenites of the Rock Creek Member· (Middle Jurassic) are subtly distinct from overlying and adjacent quartzarenites and sublitharenites of the Ellerslie (Lower Cretaceous). Chert content of the Rock Creek is consistently lower than 1.5 percent, whereas the Ellerslie ranges from 3.5 to 10 percent. Rock Creek quartzarenites are characteristically planar laminated or centimetre thick cross bedded and associated with coquinoid sandstones. Ellerslie sandstones are typically decimetre thick cross bedded and have laterally equivalent facies of lenticular bedded sandstones and shales. Rock Creek sediments were deposited on a gently sloping, storm dominated shallow marine shelf and were derived from the east. Dark marine shales of the "Upper Fernie" (Passage Beds - Kootenay equivalent) overlie the Rock Creek in places. Exposure and partial erosion of the Jurassic units occurred during early Cretaceous time resulting in a gently sloping paleodrainage system which drained the central and eastern parts of the area to the northeast. Where erosion completely cut through resistant Rock Creek sandstones to the underlying soft black shales of the Poker Chip Shale, cuestas formed on the pre-Ellerslie surface with the paleotopographic highs capped by sandstones of the Rock Creek. Early Ellerslie sandstones were fluvial and confined to valleys incised into the Jurassic. Subsequently, these sediments were conformably overlain by transitional and marine sandstones and shales, deposited by the encroaching Ellerslie Sea, which filled and covered the· pre-Ellerslie topography.Item Embargo Sequence stratigraphy, sedimentology and petroleum geology of the Glauconitic Member and adjacent(1990) Wood, James M. (James Michael); Hopkins, John C.Item Open Access Sequence stratigraphy, sedimentology and petroleum geology of the Glauconitic Member and adjacent strata, Lower Cretaceous Mannville Group, Southern Alberta(1990) Wood, James M. (James Michael); Hopkins, John C.The Lower Cretaceous Mannville Group forms part of the fill of the Cordilleran foreland basin in western Canada. Upper Mannville strata in the subsurface of the study area in southern Alberta accumulated on the cratonic side of the basin. Four upper Mannville lithostratigraphic units are informally recognized (in ascending order): Glauconitic member, and upper Mannville divisions A, B and C. Attention is focussed on the Glauconitic member and division A because many cores from oil and gas wells sample these units. Few cores sample division B, and none sample division C. The Glauconitic member and divisions A and B are differentiated based on sandstone composition, presence of valley fills, and nature of sedimentary structures, paleosols and coals. Upper Mannville strata accumulated in coastal plain settings located landward of fully marine environments. Deposition evolved in response to changes in sediment supply and relative sea level. The Glauconitic member accumulated dominantly in estuarine environments, whereas divisions A, B and C accumulated dominantly in fluvial and deltaic environÂments. The change in depositional setting coincided with a change in sandstone composition from quartzose to lithoÂfeldspathic. These changes occurred because sediment influx from the orogenic belt began to outstrip accommodation in this part of the foreland basin, and the boreal sea concomitantly regressed generally northward. Valley fills and paleosols in the Glauconitic member and division A indicate the presence of unconformity bounded sequences that formed through numerous cycles of fluvial incision and subaerial exposure followed by aggradation. These cycles, which are interpreted to have been induced by fluctuations of relative sea level, resulted in significant changes in coastal plain deposition. The Glauconitic member accumulated in inner estuarine environments that were confined within valleys when sea level was low, and in outer estuarine bays that covered interfluves when sea level was high. Division A accumulated in fluvial channels that were confined within valleys when sea level was low, and in shallow deltas that covered interfluves when sea level was high. Most of the oil produced in the study area comes from the Glauconitic member. Reservoir sandstones in valley fills are thick, elongate pods that formed from longitudinal bars when inner estuarine deposition was confined within valleys. Reservoir sandstones outside valley fills are thin sheets that formed from coalesced sand shoal and tidal channel deposits when outer estuarine bays spread across interfluvial areas adjacent to the valleys. Common updip seals for both types of reservoirs are formed by (1) intrasequence facies changes from sandstone to shale, and (2) younger, cross-cutting valley fills in division A which contain low-permeability lithofeldspathic sandstone.Item Open Access Significance of mixed carbonate-siliciclastic sedimentation in the Mississippian Banff Formation, greater Cessford area, southeastern Alberta(1997) Goldthorpe, Alice G.; Hopkins, John C.Item Embargo Stratigraphy, sedimentology and paleotopography of the lower jurassic in the Gilby-Medicine River fields, Alberta(1980) Rall, Robert D.; Hopkins, John C.Item Open Access The Environment of deposition, petrography and diagenesis of the Basal Belly River sandstone of central Alberta(1986) Doig, D. J.; Hopkins, John C.