bluuebunny/crossref_metadata_2025 huggingface dataset:
A new species of the Paleocene primate Elphidotarsius Gidley: its stratigraphic position and evolutionary relationships
Authors: Fox Richard C.
Published: November 2010

A new species of the primitive carpolestid primate Elphidotarsius Gidley is described from relatively complete upper and lower dentitions collected from the upper Paleocene Paskapoo Formation of central Alberta, Canada. Dentally, this new species shows a combination of primitive and advanced features in a more realistic approximation of the evolutionary transition between Elphidotarsius and Carpodaptes than had been available before. This new species occurs at the same horizons as does the plesiadapiform primate Plesiadapis rex (Gidley) and, hence, is middle Tiffanian in age; it occurs with Carpodaptes hazelae Simpson, at a horizon well within the Carpodaptes zone, and is the youngest discovered species of the genus. The late occurrence of a species of Elphidotarsius brings into question the biostratigraphic utility of the succession of carpolestid species for zonation of the nonmarine upper Paleocene of North America.
U–Pb systemstics in single zircons from the Pontiac sediments, Abitibi greenstone belt
Authors: Gariépy Clément , Allègre Claude J. , Lajoie Jean
Published: November 2010

Twenty-six detrital zircon grains from the late Archaean Pontiac sediments of the Abitibi greenstone belt were dated individually by the U–Pb method in order to identify possible elements of an ancient (pre-2.7 Ga) shield. The results show that at least two components were present at the source areas of these sediments: (1) materials of about 2700–2725 Ma, which were most likely derived from contemporaneous acid igneous rocks; and (2) significantly older materials, parts of which are at least 2940 Ma old, which were either part of an uplifted sedimentary basin or a sialic basement complex. These results can be used to suggest a close link between igneous activity and basin subsidence and that the development of the Abitibi volcanic belt was closely associated with the presence of some older sialic blocks.
U–Pb zircon ages from Athapuscow aulacogen, East Arm of Great Slave Lake, N.W.T., Canada
Authors: Bowring S. A. , Schmus W. R. Van , Hoffman P. F.
Published: November 2010

Athapuscow aulacogen is an Early Proterozoic intracratonic basin located in the East Arm of Great Slave Lake between the Slave and northwest Churchill provinces. Athapuscow aulacogen comprises three stratigraphic sequences, the Wilson Island Group, the Great Slave Supergroup, and the Et-Then Group. New U–Pb zircon ages provide constraints on the development of the aulacogen.The Blachford Lake Intrusive Suite consists of an older alkaline phase (Hearne Channel Granite) dated at 2175 ± 7 Ma and a younger peralkaline phase (Thor Lake Syenite) dated at 2094 ± 10 Ma, confirming the suggestion that the two phases may not be related. A felsite from the Wilson Island Group has an age of 1928 ± 11 Ma. The Wilson Island Group is intruded by epizonal granites (Butte Island Intrusive Suite), one of which has an age of 1895 ± 8 Ma. The Wilson Island Group and the Butte Island Instrusive Suite are entirely allochthonous with respect to the Slave craton. Rocks of the Great Slave Supergroup overlie mylonitized Wilson Island Group rocks and both were involved in northeast-directed thrusting. The Compton laccoliths intrude rocks of the Great Slave Supergroup, postdate thrusting, and are about 1865 Ma old.The Blachford Lake Intrusive Suite is significantly older than both the rift sequence in Wopmay Orogen (ca. 1900 Ma) and the Wilson Island Group; it probably is genetically unrelated. The age of the Wilson Island Group and Butte Island Intrusive Suite is considerably younger than previous estimates and is close to the minimum age of rifting in Wopmay Orogen. The Compton laccoliths are very similar to intrusive rocks in the Great Bear Magmatic Zone of Wopmay Orogen and may be related to east-dipping subduction beneath the aulacogen.The new ages strengthen the correlations between Athapuscow aulacogen and Wopmay Orogen and suggest a link with events in the Trans-Hudson Orogen to the south.
A tectonic window in central Newfoundland? Geological evidence that the Appalachian Dunnage Zone may be allochthonous
Authors: Colman-Sadd S. P. , Swinden H. S.
Published: November 2010

In the Through Hill area of central Newfoundland, mafic to ultramafic complexes, which preserve varying amounts of ophiolite stratigraphy, mark the trace of a major fault zone that outcrops in a roughly elliptical pattern. The major, northeast-trending axis is about 60 km and the shorter axis is about 30 km in length. The most complete ophiolite stratigraphy is preserved in the Coy Pond and Pipestone Pond complexes, which have steep dips and face east and west, respectively, outwards from the centre of the ellipse.The ophiolitic rocks are bounded on the outside by rocks typical of the Dunnage Zone of central Newfoundland, principally Lower to Middle Ordovician volcanic and volcaniclastic rocks interpreted to be of island-arc affinity (Davidsville, Victoria Lake, and Baie d'Espoir groups, Cold Spring Pond Formation) and Upper Ordovician to Silurian clastic sediments (Botwood Group). The volcano-sedimentary sequences are interpreted to have been deposited on the ophiolite conformably, but the contacts are not exposed. Both ophiolite and volcano-sedimentary sequences have similar structural and metamorphic histories, exhibiting one principal deformation and the formation of folds with subhorizontal axes, local development of second-generation folds and associated cleavage, and an intervening period of metamorphism in the greenschist facies.The elliptical area enclosed by the ophiolite belt is referred to as the Mount Cormack Terrane, and is underlain by variably metamorphosed shale, quartz-rich sandstone, quartzo-feldspathic to amphibolitic gneisses, and granite. A limestone occurrence contains shelly fossils of Early to Middle Ordovician age. An early deformation formed folds with steep axes, and subsequent metamorphism resulted in a progression from greenschist facies to upper amphibolite facies, with the production of migmatite and granodiorite.The preferred interpretation of the geology is that the elliptical Mount Cormack Terrane is exposed as a window through an overlying allochthon composed of ophiolitic and volcano-sedimentary rocks of the Dunnage Zone. The emplacement of the allochthon probably postdated deposition of the Silurian Botwood Group. Paleontologic, lithologic, and structural considerations suggest that the sediments of the Mount Cormack Terrane were deposited at the eastern margin of Iapetus and are perhaps correlatives of rocks exposed in the Gander Zone. This implies that the Dunnage Zone has been thrust, probably in an eastwards direction, on a scale comparable with the allochthons mapped in the Scandinavian Caledonides and proposed for the Appalachians of Quebec and the United States.
Fossil mammals of the Southfork Local Fauna (early Chadronian) of Saskatchewan
Authors: Storer John E.
Published: November 2010

The Southfork Local Fauna, Cypress Hills Formation, Cypress Hills Plateau, southwestern Saskatchewan, is distinctly older than the nearby Calf Creek Local Fauna. Co-occurrence at Southfork of Hyracodon petersoni, Brachyhyops viensis, Leptomeryx cf. L. yoderi, and Leptomeryx cf. L. blacki indicates biostratigraphic correlation low in the early Chadronian. Presence of Oligocene local faunas of different ages strengthens the concept of a faunal succession in the Cypress Hills Formation, and emphasizes the importance of considering Cypress Hills assemblages locality by locality.
A glaciofluvial origin for drumlins of the Livingstone Lake area, Saskatchewan
Authors: Shaw John , Kvill Donald
Published: November 2010

The Livingstone Lake drumlin field of northern Saskatchewan is on the Athabasca Plains. It is draped over high ground underlain by the Precambrian Athabasca Sandstone. The drumlins occur in spindle, parabolic, and transverse asymmetrical forms. A map of individual drumlins shows that features of similar form occur together. The drumlins are related on a regional scale to even larger landforms. There is also an arrangement of drumlins in streams parallel to the assumed flow direction. These patterns illustrate spatial organisation of the drumlin-forming flows. The Livingstone Lake drumlins are closely related to tunnel valleys, large crescentic scours, and eskers. Exposed bedrock reveals widespread scalloping and sichelwannen. An argument is made that drumlins are related to these glaciofluvial forms but were created at different times and by different flows than those forming small-scale flutings and other lodgment features. Sediments within the drumlins are mainly primary water-sorted deposits some of which were resedimented by mass movements. There are also large, striated boulders. Deposition in subglacial cavities is suggested. This explanation is supported by a comparison of patterns and forms of erosional marks produced by wind and water and the implied form of the subglacial cavities. The Livingstone Lake drumlins are considered to represent infillings of cavities developed by meltwater erosion of the underside of glaciers. This conclusion stresses the geomorphic and sedimentologic importance of subglacial meltwater. It has important implications for the behaviour of the large Pleistocene ice sheets and the interpretation of glacigenic sediments. Consequently, it has direct bearing on glacial stratigraphy and chronology.
The Picton and Varty Lake ultramafic dikes: Jurassic magmatism in the St. Lawrence Platform near Belleville, Ontario
Authors: Barnett R. L. , Arima M. , Blackwell J. D. , Winder C. G. , Palmer H. C. , Hayatsu A.
Published: November 2010

The Picton and Varty Lake ultramafic dikes that intrude Ordovician limestone near Belleville, Ontario, consist of olivine or serpentinized pseudomorphs and Ti-phlogopite phenocrysts set in a groundmass of spinel, perovskite, serpentine, calcite, apatite, and chlorite. Phlogopite exhibits a complex chemical variation and late-stage Ba enrichment (up to 6.8 wt.% BaO). Spinels are chemically zoned and commonly exhibit an atoll texture in which a magnesian–aluminous chromite core is separated by a silicate zone from late-stage magnesian–aluminous titanomagnetite chemically similar to kimberlitic spinel. Atoll spinels from the Picton dike also have a zone of titanian pleonaste surrounding a central grain of magnesian–aluminous chromite at the centre of the atoll structures. Both dikes are extremely silica undersaturated, with high K/Na and Mg/(Mg + Fe2+) ratios. Petrographic and chemical features of the Picton and Varty Lake dikes preclude simple classification, as both dikes have aspects indicative of kimberlitic and lamprophyric affinities. K–Ar age determinations, indicating a Jurassic age of emplacement for both dikes, are supported by paleomagnetic data from the Picton dike. The Varty Lake dike yielded no stable paleomagnetic remanence directions; limestone adjacent to the dike retains a Paleozoic remanence possibly indicating a very low emplacement temperature. The emplacement of both dikes may be related to Grenville-age basement faults reactivated in Jurassic time.
Paleomagnetism of the Hearst dike swarm and implications for the tectonic history of the Kapuskasing Structural Zone, northern Ontario
Authors: Ernst Richard E. , Halls Henry C.
Published: November 2010

Prominent north- to northwest-trending dikes (herein termed the Hearst swarm) west of the Kapuskasing Structural Zone (KSZ) in northern Ontario yield a paleomagnetic pole position of 48.6°N, 69.0°E, dm = 6.9, dp = 3.6 (60 samples from 12 dikes).Using paleomagnetic, petrographic, and structural criteria the Hearst swarm is correlated with the 2.6 Ga Matachewan swarm east of the KSZ. A positive correlation is observed between the trend and paleomagnetic declination of Hearst–Matachewan dikes and may result from an ~15 °post-2.6 Ga rotation of terranes across the KSZ.Paleomagnetic and structural data from the Hearst dikes are consistent with the regional westward tilting of the crust near the southern KSZ as first proposed in 1983 by Percival and Card.
Characterization of LRRFIP1
Authors: Arakawa Rachel , Bagashev Asen , Song Li , Maurer Kelly , Sullivan Kathleen E.
Published: November 2010

LRRFIP1 has been identified as a regulator of toll-like receptor (TLR) pathway signaling; however, little is known about its own regulation and function. This study was undertaken to characterize the biochemical properties and its regulation. Over-expression of full length LRRFIP1 led to enhanced responses to lipopolysaccharide (LPS). We examined its expression in monocytic cell lines because they express a broad range of TLRs. We found that its level of expression was not altered by LPS or phorbol myristate acetate (PMA) but that it was up-regulated by nicotine, influenza infection, and serum starvation. Phosphorylation was examined because of the bioinformatically predicted serine phosphorylation sites. Serine phosphorylation was detected and was altered by both poly I:C and nicotine. Finally, we examined the regulation of intracellular localization in response to dsRNA and found that LRRFIP1 colocalized with labeled dsRNA in monocyte lysosomal structures but not with lysosomes lacking dsRNA. These data suggest that LRRFIP1 is phosphorylated in response to immunologic stimuli and it is directed to lysosomal structures.
Effect of FKBP65, a putative elastin chaperone, on the coacervation of tropoelastin in vitro
Authors: Cheung Kevin L.Y. , Bates Matthew , Ananthanarayanan Vettai S.
Published: November 2010

FKBP65 is a protein of the endoplasmic reticulum that is relatively abundant in elastin-producing cells and is associated with tropoelastin in the secretory pathway. To test an earlier suggestion by Davis and co-workers that FKBP65 could act as an intracellular chaperone for elastin, we obtained recombinant FKBP65 (rFKBP65) by expressing it in E. coli and examined its effect on the coacervation characteristics of chicken aorta tropoelastin (TE) using an in vitro turbidimetric assay. Our results reveal that rFKBP65 markedly promotes the initiation of coacervation of TE without significantly affecting the temperature of onset of coacervation. This effect shows saturation at a 1:2 molar ratio of TE to rFKBP65. By contrast, FKBP12, a peptidyl prolyl isomerase, has a negligible effect on TE coacervation. Moreover, the effect of rFKBP65 on TE coacervation is unaffected by the addition of rapamycin, an inhibitor of peptidyl prolyl isomerase (PPIase) activity. These observations rule out the involvement of the PPIase activity of rFKBP65 in modulating the coacervation of TE. Additional experiments using a polypeptide model of TE showed that rFKBP65, while promoting coacervation, may retard the maturation of this model polypeptide into larger aggregates. Based on these results, we suggest that FKBP65 may act as an elastin chaperone in vivo by controlling both the coacervation and the maturation stages of its self-assembly into fibrils.
Truncation attenuates molecular chaperoning and apoptosis inhibition by p26, a small heat shock protein fromArtemia franciscana
Authors: Wu Yong , MacRae Thomas H.
Published: November 2010

The small heat shock proteins (sHSPs), which prevent irreversible protein denaturation and inhibit apoptosis, consist of an amino-terminus, the canonical α-crystallin domain, and a carboxy-terminal extension. It remains difficult, however, to define sHSP structure–function relationships and with this in mind p26, an sHSP from the crustacean Artemia franciscana , was truncated by deletion mutagenesis. Wild-type p26 cDNA and three truncated variants inserted into the eukaryotic expression vector pcDNA3.1/HisC were used to generate stably transfected 293H cells. p26 shielded transfected cells against death upon exposure to heat and oxidative stress. Truncation reduced chaperone activity, with cells synthesizing the p26 α-crystallin domain being the least resistant. Wild-type p26 inhibited apoptosis in transfected cells, with protection against oxidation-generated apoptosis being more effective than that against heat-induced apoptosis. Truncation reduced p26 apoptotic inhibitory activity, with the α-crystallin domain again being the least effective. The results show that a crustacean sHSP functions effectively in mammalian cells, demonstrating interchangeability of these proteins between distantly related organisms and indicating similarities in their mechanisms of action. Moreover, maximal activity was observed for full-length p26, indicating that structural elements required for chaperone activity and apoptosis inhibition reside throughout the protein.
EXPOSING DIGITAL VIDEO LOGO-REMOVAL FORGERY BY INCONSISTENCY OF BLUR
Authors: SU YUTING , ZHANG JING , HAN YU , CHEN JING , LIU QINGZHONG
Published: November 2010

A novel approach for detecting video logo-removal forgery is proposed by measuring inconsistency of blur. Our approach is based on the assumption that if a digital video undergoes logo-removal forgery; the blurriness of the forged region is expected to be different as compared to the nontampered parts of the video. Blurriness is first estimated by analyzing the spatial and temporal statistical property of logo areas, and suspicious areas are roughly located; then features are extracted and a fine classification is implemented by applying support vector machine (SVM) to extract features. If the suspicious areas and the reference areas are classified into different classes, the video is judged as a forged video. Experimental results show that our method is robust to video lossy compression for logo-removal forgery detection with the advantages of high classification accuracy and low computation cost.
VON NEUMANN, VILLE, AND THE MINIMAX THEOREM
Authors: BEN-EL-MECHAIEKH HICHEM , DIMAND ROBERT W.
Published: November 2010

Von Neumann proved the minimax theorem (existence of a saddle-point solution to 2 person, zero sum games) in 1928. While his second article on the minimax theorem, stating the proof, has long been translated from German, his first announcement of his result (communicated in French to the Academy of Sciences in Paris by Borel, who had posed the problem settled by Von Neumann's proof) is translated here for the first time. The proof presented by Von Neumann and Morgenstern (1944) is not Von Neumann's rather involved proof of 1928, but is based on what they called "The Theorem of the Alternative for Matrices" which is in essence a reformulation of an elegant and elementary result by Borel's student Jean Ville in 1938. Ville's argument was the first to bring to light the simplifying role of convexity and to highlight the connection between the existence of minimax and the solvability of systems of linear inequalities. It by-passes nontrivial topological fixed point arguments and allows the treatment of minimax by simpler geometric methods. This approach has inspired a number of seminal contributions in convex analysis including fixed point and coincidence theory for set-valued mappings. Ville's contributions are discussed briefly and von Neuman's original communication, Ville's note, and Borel's commentary on it are translated here for the first time.
TECHNICAL EFFICIENCY OF EFFORTS TO ENHANCE INNOVATIVENESS IN THE EUROPEAN UNION
Authors: NASIEROWSKI W.
Published: November 2010

The objective of this paper is to clarify whether or not the so-called innovation leaders are efficient in transforming innovation inputs into outputs. The study aims to expand on the thought that the level of inputs is decisive in classification of countries as leaders, followers, or laggards in the race to improve innovativeness and competitiveness, and thus raise the standard of living. Based upon the European Innovation Scoreboard (EIS), the efficiency of investment in innovation is examined with the use of the DEA model. The use of the EIS as the main source imposes a limitation on the scope of the countries examined, yet the EIS is essentially the only comprehensive source that examines innovativeness. It is observed that the so-called laggards in innovation are often efficient in their use of resources, whereas leaders of innovation fall short in the area of returns to scale and congestion. Such an observation provides an important guide to the development of policies aimed at improving innovative efforts. Finally, through the use of the nonparametric DEA model, this paper provides a methodological extension to the methods for investigation of innovation systems.
THE APPLICATION OF FEATHER KERATIN AND ITS DERIVATIVES IN TREATMENT OF POTATO STARCH WASTEWATER
Authors: WANG RONG-MIN , LI FANG-YING , WANG XIAO-JIE , LI QUAN-FANG , HE YU-FENG , WANG YAN-BING
Published: November 2010

In this paper, stable and homogeneous feather keratin was effectively extracted from feathers. Its molecular weight is 20kDa with low dispersivity. The extracted feather keratin (FK) and its derivatives (FK-ET) were used as natural polymer flocculants. It was a new kind of effective and innoxious flocculant for the COD removal of potato starch wastewater. The removal rate of COD was up to 75% under the following optimal condition: 100mL of initial wastewater (COD = 7380), T = 20°C, [FK-ET] = 0.4g/L, [Bent] = 4g/L, pH = 8.0. Compared with traditional flocculants, keratin flocculants are innoxious natural polymers. Their sludge is easy to be treated, and there is no further pollution. Also, the flocculating constituents, which containing keratin, starch, saccharide, protein and other solubility substances from wastewaters, should be reutilized. It has practical application value in water treatment as a kind of natural polymer flocculant.
Geological modelling of a reservoir analogue; Cenozoic meander belts, Loranca Basin, Spain
Authors: Diaz-Molina M. , Arribas J. , Gómez J. J. , Tortosa A.
Published: November 2010

The reconstruction of meander belts was approached by detailed geological mapping, the interpretation of exposed sandstone bodies and the application of sedimentological concepts. The single reconstructed meander belts were integrated, considering stratigraphic position and thickness in a three-dimensional model of the depositional architecture. Some useful reservoir parameters, such as volume of meander loops, areas of interconnection and fluid flow barriers, are calculated from the obtained model. Sandstone porosity is mainly of primary origin and mechanical compaction is the most intense diagenetic feature. Models of estimated permeability evolution in the point bar sequences have been developed. Gamma ray readings from different lithologies were obtained and grouped according to their palaeoenvironmental classification. The results are comparable to well logs and aid subenvironmental characterization of continental deposits.
Natural gas storage in the South Kavala Field; geological and seismological characteristics
Authors: Georgakopoulos A. N. , Papaconstantinou C. M. , Papaioannou C. A.
Published: November 2010

The South Kavala Field will have produced 670 x 10
6
Sm
3
of its original recoverable gas reserves of 1.0 x 10
9
Sm
3
by the end of 1994. Gas storage of imported gas is planned, and to provide continuity of supply and to reduce the risk of induced seismicity caused by pressure variation in the reservoir, the remaining 300 x 10
6
Sm
3
will be used as a cushion. the field lies nearby seismically active areas so the seismic hazard is evaluated. Even though the seismicity of the area is low, it is considered prudent to install a dense network of seismographs in order to monitor the effects of small magnitude (M
s
< or = 2.5) earthquakes.
Challenges in modelling reservoirs in the North Sea and on the Norwegian Shelf
Authors: Henriquez Adolfo , Jourdan Charles
Published: November 2010

Reliable predictive models for hydrocarbon production in the high cost Norwegian Offshore have required the development and application to full field simulation of a range of improved 3D geological reservoir modelling techniques. The authors' philosophy for reservoir modelling is outlined and attention focused on the acquisition of the correct type of data, understanding their frequently large inherent uncertainties, and the use of stochastic geological modelling, which, if handling advanced geological concepts and analogue data, enable a proper investigation of the effects of reservoir heterogeneity on fluid flow. Quicker and more trustworthy history matching and 'repairs' of models are made possible. There are challenges to be faced within areas such as geological concepts, estimation of Sw, Sor, and permeability, upscaling, ranking of realizations, the use of 3D seismic to determine lithological and fluid compositions and the conditioning of stochastic models using seismic attributes, well test and production data.
Analytical up-scaling of small-scale permeability using a full tensor
Authors: Aasum Yngve , Kasap Ekrem , Kelkar Mohan
Published: November 2010

An analytical method is developed to calculate an effective permeability tensor for a grid block by accounting for small-scale heterogeneity within the grid block. The method honours both the location and the orientation of the smallscale heterogeneity. Effective permeability tensors calculated using the analytical method and a numerical method show excellent agreement. Single phase flow simulations show that the effective permeability tensor method outperforms nontensor scale-up techniques in predicting the fluid flow distances in cases of general permeability anisotropy. The tensor method was also applied to two-phase flow simulations and it was shown that it retains the directionality in preferential flow paths after up-scaling.
Using 3D seismic to understand the structural evolution of the UK central North Sea
Authors: Eggink J. W. , Riegstra D. E. , Suzanne P.
Published: November 2010

Interpretation of regional 3D seismic data suggests that the structural evolution of the Central North Sea occurred in three successive structural regimes. Two successive extensional tectonic regimes from Late Palaeozoic to Early Cretaceous were followed by a predominantly compressive tectonic regime from the Late Cretaceous into the Tertiary. Tectonic movements were controlled by the relative orientation of the stress fields with respect to the fault strikes of older major Variscan fault trends. The amount and direction of strike-slip movement was controlled by a gradual clockwise rotation of the minimum effective stress in the horizontal plane from approximately NE-SW to E-W in the first two phases. Within this framework, halokinesis is only of local importance, and serves to amplify the tectonically controlled structuration. The structural model developed here explains the observed distribution of fields and structures in the Central Graben, as well as enabling prediction of structural development in its less well explored portions.
In situ characterization of chalk cores using a nuclear tracer imaging technique
Authors: Eleri Ogbonnia O. , Graue Arne , Anowi Ogugua , Skauge Arne
Published: November 2010

Core-flood experiments using chalk outcrop cores with petrophysical properties similar to North Sea chalk reservoirs have been conducted and history-matched. The objectives were to enhance the understanding of the mechanisms of fluid displacement in permeable chalk and to evaluate the imaging technique with respect to measuring three-phase saturations in chalk cores. The displacements included miscible brine/brine, drainage, miscible oil floods and water floods. The brine and oil phases were respectively labelled with gamma-emitting
22
Na and
59
Fe tracers. Fluid saturations were measured by a Germanium detector moved along the length of the core. In this investigation, emphasis has been placed on local in situ saturation development, recovery efficiency, fluid-front behaviour and tracer adsorption. The benefits from knowing the local in situ saturations, the identification of rock heterogeneity and the reproducibility of the saturation imaging have been emphasized. A good comparison was obtained between in situ fluid saturation information and that from effluent fluid measurements. The additional information on local fluid saturations obtained from the in situ measurements, coupled with petrophysical measurements, has enhanced the characterization of chalk cores and thus will contribute to a better understanding of displacement mechanisms during hydrocarbon recovery from chalk reservoirs. The nuclear tracer imaging technique was found suitable for measurements of three-phase fluid saturations.
The nature and diversity of pressure transition zones
Authors: Swarbrick Richard E. , Osborne Mark J.
Published: November 2010

Pressure transition zones occur where the rate of pressure increase or decrease exceeds a fluid gradient. Transition zones are found between intervals of permeable rock and, in each case, fluid movement is impeded by a 'seal', which acts as a temporary barrier over geological time. The composite profile of pressure vs. depth is a function of three phenomena: (1) the mechanism responsible for abnormal pressure, (2) redistribution of pressure due to fluid movement during and after the mechanism is occurring, and (3) the lithological profile of the rock succession. Pressure profiles in some overpressured systems can reveal which of the mechanisms is causing the overpressure. Once overpressure has been created, pressure decay and transference away from the interval of generation can strongly influence the nature of transition zones. Transition zones are controlled in a fundamental way by the permeability of the rocks in which the abnormal pressure is found.
A fluid dynamic classification of hydrocarbon entrapment
Authors: Heum O. R.
Published: November 2010

Fluid dynamic potentials are critical to the entrapment, distribution, phase, leakage and migration of hydrocarbons. The classification system combines two cap rock properties (static and dynamic) with five seal and leakage modes (capillary seal, pressure seal, hydraulic resistance seal, water drive leakage and hydraulic fracturing leakage) and two hydrocarbon migration mechanisms into and out of a trap (fill/spill and fill/leak). Static cap rocks, such as thick shales, usually seal more than the vertical closure of the trap, as a consequence of the critical pore throat capillary pressure (capillary seal). In two-phase hydrocarbon systems fill/spill tends to concentrate gas. Hydraulic fracturing is usually required to generate significant leakage through static cap rocks. Then fill/leak tends to concentrate oil. Dynamic cap rocks, such as inhomogeneous sand/shale sequences and faults have less sealing capacity than the static cap rocks, but are more widespread. They are strongly affected by variations in the fluid dynamic properties and are less dependent on capillary pressure. Water potentials are often critical, for seal (pressure seal) or for leakage and redistribution (water drive leakage). Hydraulic resistance seal is important for trapping of oil and crucial for concentration of oil relative to gas (fill/leak).
Tertiary extensional fault systems on the western margin of the North Sea basin
Authors: Stewart Simon A.
Published: November 2010

Major thin-skinned fault systems of Tertiary age, detaching on Permian salt, are present on the platform west of the Central Graben in the Central and Southern North Sea. In plan view the fault systems describe two large arcs which are separated by the Mid North Sea High, partially encircling the West Central Shelf of the Central North Sea and the Silver Pit Basin in the Southern North Sea. The fault trends broadly follow the strike of base salt topography. The geometry of individual faults reflects lateral variation in the role of basement faults and pre-existing Mesozoic thin-skinned extensional structures. Dominant down-to-the-basin fault polarity suggests that the fault systems represent the limit of a gravity-driven slip zone. Extension is largely balanced by down-dip growth of fold structures. Further implications for hydrocarbon exploration include growth of roll-over fold closures adjacent to the fault zones and creation of a tectonic barrier to up-dip fluid migration.
Reservoir quality and burial diagenesis in the Statfjord Formation, North Sea
Authors: Ramm Mogens , Ryseth Alf E.
Published: November 2010

This paper presents models for reservoir quality prediction in the dominantly fluvial reservoir sandstones in the Lower Jurassic Statfjord Formation in the North Viking Graben. The models are based on theory and on empirical observations from wells from the Norwegian sector of the North Sea. At depths shallower than 3000 m, porosity and permeability in the Statfjord Formation sandstones show systematic trends versus burial depth and the net-togross ratio is mainly a function of the amount of sand deposited. Hence, confident reservoir quality prediction at shallow burial may be founded on regional or subregional models that address sandstone architecture and on regional or sub-regional porosity and permeability versus depth trends. Beneath 3000-3500 m, however, the reservoir quality is more variable due to variations in porosity and permeability reduction following compaction, quartz cementation and formation of fibrous illite. Between 3000 and 4000 m, formation of quartz cement and fibrous illite reduce the permeability and the net-to-gross ratio. Accordingly, permeability lower than 1 mD and net-to-gross ratios less than half the initial sandstone content are expected in many prospects below 4000 m. In some deeply buried reservoirs, porosity loss by quartz cementation and compaction is retarded by chlorite coatings or by high pore pressure. Good permeability may be preserved to depths greater than 4000 m if the porosity is preserved (i.e. by a high overpressure or chlorite coatings) and if illitization is hindered by limited potassium supply.
Vendian and Riphean basins and prospectivity on the East European Platform
Authors: Fedorov D. L.
Published: November 2010

Riphean-Vendian strata represent the lowest stratigraphic interval of the East European Platform which could contain undiscovered hydrocarbons. Regional geophysical surveys in the 1990s have aimed at studying the structural features and petroleum potential of the ancient strata of the Moscow syneclise. In the central parts of the platform, Riphean deposits fill deep and extensive graben systems superposed by basins containing thick Vendian sequences. Middle Riphean and Upper Vendian clay-siltstone strata of coastal-marine origin are rich in organic matter of sapropelic type and are source rocks. The geological and geochemical environment is favorable for the formation of oil and gas pools. The main exploration aim is to detect zones with all the criteria favourable for the presence of hydrocarbons, modern geophysical and geochemical exploratory methods playing a crucial role.
Overpressure and hydrocarbon trapping in the chalk of the Norwegian Central Graben
Authors: Caillet G. , Judge N. C. , Bramwell N. P. , Meciani L. , Green M. , Adam P.
Published: November 2010

The hydrodynamic system within the Chalk of the Greater Ekofisk area and its effect upon pore pressure distribution and hydrocarbon trapping has been analysed. The Chalk of the area is a relatively closed system for fluid movement and has large pressure cells characterized by their own pressure regime, fluid type and trapping potential. The aquifer is near static and there is no significant regional hydrodynamic flow. Overpressure is higher at Valhall than at Eldfisk, Ekofisk or Albuskjell, but Valhall is structurally shallower than Albuskjell. This trend corresponds to a maturity trend for the reservoir fluids, and is related to burial depth, temperature and hydrocarbon charging. As total pore pressure at the top of the structures reaches fracture pressure, leakage occurs. The gas cloud observed on seismic data above Valhall may be due to present-day leakage, whilst the gas clouds above other fields could be related to leakage which occurred when the fracture pressure was lower than today. Overpressuring is a dynamic process dependent on burial, hydrocarbon generation and migration, diagenesis and seal integrity and it controls both chalk porosity and hydrocarbon trapping.
The NE Atlantic margin; implications of late Mesozoic and Cenozoic events for hydrocarbon prospectivity
Authors: Dore A. G. , Lundin E. R. , Birkeland O. , Eliassen P. E. , Jensen L. N.
Published: November 2010

The study takes in the entire NE Atlantic margin (NEAM) but emphasizes the sparsely drilled More and Voring Basins. A network of Permo-Triassic and Jurassic basins was strongly overprinted by younger extensional episodes. At least three phases are probable--early Cretaceous, mid-Cretaceous and latest Cretaceous-early Eocene--between the late Jurassic and break-up. Substantial thicknesses of Cretaceous and Cenozoic strata along the margin have focused exploration interest on the late Cretaceous and Paleocene intervals as easily drillable targets. Reservoirs within these intervals were deposited as gravity-driven sand incursions into an overwhelmingly mud-prone environment. Sand pulses of Albian-Coniacian, Santonian-early Campanian and Paleocene age occur widely, and can be tied to the tectonic episodes. Vertical migration of hydrocarbons from known Jurassic source rocks is proven west of Shetlands, but in many parts of the margin remigration from intermediate reservoirs would be required to charge the shallower plays. Failing this, prospectivity will hinge on the presence of frontier source rocks, with best possibilities at Barremian, Aptian-Albian, Cenomanian-Turonian and Paleocene levels. Potential hydrocarbon traps were formed by pre-breakup extensional faulting and by post-breakup compression.
The Carboniferous of Western Europe; the development of a petroleum system
Authors: Maynard James R. , Hofmann Wolfgang , Dunay Robert E. , Benthan Pete N. , Dean Kevin P. , Watson Ian
Published: November 2010

A consistent stratigraphic study of the western European Carboniferous Basin has allowed the generation of eight palaeogeographic timeslices. These illustrate a model of large scale eastern (dextral) tectonic escape on the northern side of a convergent margin and integrate the diverse tectonic and sedimentary settings observed within the basin as a whole. This model can be compared to the present day eastern Mediterranean, where a similar range of diverse tectonic settings are observed. Reservoir and source distribution is discussed for each time-slice along with the present distribution of Carboniferous oil and gas fields. Due to the diversity observed no unique play type can be distilled from the data to explain the distribution of hydrocarbons within the studied area.
Fuzziness, incompleteness and randomness; classification of uncertainty in reservoir appraisal
Authors: Foley Lucy , Ball Leslie , Hurst Andrew , Davis John , Blockley David
Published: November 2010

The rapid progress in computer technology in recent years has enabled the development of increasingly complex simulators, which can handle large amounts of data. It is often assumed that this automatically leads to more accurate static and dynamic reservoir models. In reality, however, there is still much evidence that the predicted performance of a reservoir often differs vastly from the actual production behaviour. These deviations are an indication of the failure to understand the processes involved and to recognize the uncertainty inherent in the definition of important reservoir characteristics. In this paper, a classification scheme is proposed, in which uncertainty is expressed as fuzziness, incompleteness and randomness. Each of these elements is described in detail and illustrated within the context of reservoir appraisal, although the approach can be applied to the wider aspects of petroleum geoscience. It is believed that adopting this classification scheme will enable the geoscientist to build a more extensive picture of uncertainty in reservoir appraisal. It will also be invaluable as a tool with which to inform management of the existing uncertainty, using a consistent language, thus providing guidance in the decision-making process.
The influence of fracture stiffness and the in situ stress field on the closure of natural fractures
Authors: Hillis Richard R.
Published: November 2010

The extent to which the aperture of natural fractures is reduced, and they are rendered closed and unproductive by the in situ stress field in the subsurface, is critical to planning the exploitation of naturally fractured reservoirs. The semi-log relation between stress and the reduction of natural fracture aperture is combined with the effective normal stress acting on fractures of varying alignment with respect to the horizontal stresses to yield the relation: delta = 1/q log(n+1/2n + n-1/2n cos2theta ) + logsigma '
H
/q - p/q, where delta is the reduction of fracture aperture (fracture closure), p and q are constants in the semi-log fracture closure/stress relation, sigma '
H
is the maximum effective horizontal stress magnitude, n is the ratio between the maximum and minimum effective horizontal stress magnitudes, and theta is the angle between the normal to the fracture and the sigma
H
direction. Key conclusions from this relation are: (i) for a given fracture, the sensitivity of fracture closure to the anisotropy of the in situ stress field can be constrained by the effective horizontal stress ratio; (ii) natural fracture closure is very sensitive to fracture alignment with respect to sigma
H
where the effective horizontal stress ratio is high; (iii) the sensitivity of natural fracture closure to its alignment with respect to sigma
H
decreases markedly as the effective horizontal stress ratio drops; (iv) except where the effective horizontal stress ratio is infinite, the rate of change of closure with changing alignment is relatively low at very low and at high misalignment angles, and much greater at intermediate angles. The above relation is applied to a number of fractures for which the closure/stress relations have been determined. With varying alignment with respect to sigma
H
, less stiff fractures show up to four times more closure than stiff fractures.
Petroleum potential of dysaerobic carbonate source rocks in an intra-shelf basin; the Lower Cretaceous of Provence, France
Authors: Machhour L. , Masse J. P. , Oudin J. L. , Lambert B. , Lapointe P.
Published: November 2010

Barremian-Aptian carbonate sediments in southern Provence belong to a drowning sequence within an intra-shelf basin and display organic-carbon-rich horizons corresponding to the demise of a rudists platform system and the onset of dysaerobic conditions. These horizons depart from the classical anoxic model accepted for most marine organic-carbon-rich deposits. They have a rich and diverse fauna documenting nutrient-rich waters with low oxygen content--an environment in which organic matter is preserved from both biological and chemical degradation. Sedimentological, geochemical and palaeoecological investigations suggest that the organic-carbon-rich carbonates reflect dysaerobic conditions favourable for organic matter preservation, the amount of dissolved oxygen being lower than the geochemical threshold for organic matter decay. These organic-carbon-rich sediments are the result of high sea surface productivity and sea bottom conditions favouring preservation. The kerogen is mainly amorphous sapropelic organic matter, essentially algal, with a high hydrogen index and is of marine origin, deposited during high sea-level.
Subcircular features and autotracking artefacts in 3D seismic interpretation; a case study from the central North Sea
Authors: Bizarro P.
Published: November 2010

Tertiary deep-water sandstones are major reservoirs in the North Sea, and display an upward gradation from sheet-like bodies to increasingly channelized units. 3D seismic horizon attribute maps at near Top Forties and Top Chalk levels within the Central North Sea portray peculiar textures, which were found to be genuine, and not the result of artefacts caused by the use of autotracking in seismic interpretation. The semi-circular fabric of the near Top Forties event is the result of pre-existing NW-SE structural trends, depositional processes and differential compaction. The pockmark pattern displayed by the Top Chalk horizon is associated with small-scale fractures related to reactivated shear zones and to episodic overpressure release. Use of attribute maps and time slices highlights elusive features, thus refining fairway delineation and understanding of fracture network properties, leading to improved reservoir description and management.
The salt pillow to diapir transition; evidence from unroofing unconformities in the Norwegian-Danish Basin
Authors: Sorensen Kai
Published: November 2010

Salt diapirs in the Norwegian Danish Basin are characterized by the occurrence of marked angular unconformities which dip towards the diapirs. These unconformities developed above salt pillows, showing that the pillows grew close to the surface, or even reached the surface, in the time interval predating diapir formation. By contrast, the unconformities above present-day pillows show that these pillows have never reached close to the surface, strongly suggesting that pillow growth to "near unroofing" was a necessary condition for a transition to diapirism. Evidence from pillows indicates that unroofing in some cases was an asymmetric process involving growth of the pillow on the footwall side of a fault which soles out on the top surface of the salt. A consequence of this mechanism is that a separate stage of salt structure growth, with a combination of both pillow and diapir features, must be included in a general model for the "classical" Zechstein basin salt structures.
Reservoir development, sequence stratigraphy and geological modelling of Westphalian fluvial reservoirs of the Caister C Field, UK southern North Sea
Authors: Ritchie J. S. , Pilling D. , Hayes S.
Published: November 2010

The earliest Westphalian B reservoir of the Caister C Field (informally named the Caister Sandstone Unit consists of erosive conglomeratic sandstones deposited in stacked low sinuosity fluvial channels. Channel types and architectural elements demonstrate an upward change to more sinuous forms. The Caister Sandstone Unit is believed to contain incised valley-fill sediments deposited as late lowstand and transgressive systems tracts when rising base level generated accommodation space. The dominant control on reservoir quality is primary depositional texture with the best permeability found in higher energy coarse sandstone and pebbly intervals associated with basal channel-fill units; crevasse channel and splay sandstones offer poor reservoir properties. The robust correlation framework, which is based upon laterally extensive coal seams, enables a sequence stratigraphic model of the field to be developed, thereby allowing a better understanding of reservoir extent and sandbody continuity. A 3D geocellular geological model is built with reservoir architecture elements controlled by the sedimentological model. This is used for volumetrics calculations, input to a reservoir simulator and in the locating and planning of in-fill wells.