Evaluation of the Reduction in Uncertainty Obtained by Conditioning a 3D Stochastic Channel to Multiwell Pressure Data

A stochastic channel embedded in a background facies is conditioned to data observed at wells. The background facies is a fixed rectangular box. The model parameters consist of geometric parameters that describe the shape, size, and location of the channel, and permeability and porosity in the channel and nonchannel facies. We extend methodology previously developed to condition a stochastic channel to well-test pressure data, and well observations of the channel thickness and the depth of the top of the channel. The main objective of this work is to characterize the reduction in uncertainty in channel model parameters and predicted reservoir performance that can be achieved by conditioning to well-test pressure data at one or more wells. Multiple conditional realizations of the geometric parameters and rock properties are generated to evaluate the uncertainty in model parameters. The ensemble of predictions of reservoir performance generated from the suite of realizations provides a Monte Carlo estimate of the uncertainty in future performance predictions. In addition, we provide some insight on how prior variances, data measurement errors, and sensitivity coefficients interact to determine the reduction in model parameters obtained by conditioning to pressure data and examine the value of active and observation well data in resolving model parameters.     

A Reflection on Mg, Cd, Ca, Li and Si Isotopic Measurements and Related Reference Materials

This contribution aims to report the reflections we had with the scientific community during two international workshops on reference materials for stable isotopes in Davos (2002) and Nice (2003). After evaluating the isotopic homogeneity of some existing reference materials, based on either certificates, literature data or specific inter-laboratory rounds, we confirm these as primary reference materials or propose new ones relative to which stable isotope compositions should be reported. We propose DSM-3 for Mg, NIST SRM 915a for Ca, L-SVEC for Li and NBS28 for Si. Cadmium does not yet have a well identified delta zero material, although three commercial mono-elemental Cd solutions have yielded the same isotopic composition relative to one another. In order to scale the linearity of any mass spectrometer, some secondary reference materials are also proposed: Cambridge-1 solution for Mg, the "Münster-Cd" and JEPPIM Cd solutions for Cd and the "Big Batch" silicate for Si. The team from Nancy propose to prepare a mixed spike solution for Li isotopes. Well-characterised natural samples such as ocean or continental waters, diatoms, sponges, rocks and minerals are needed to validate the entire analytical procedure, particularly to take into account the effect of sample mineralisation and of chemical manipulations for elemental separation prior to analysis.     

Tektonik und zyklische Sedimentation in der helvetischen Zone der Schweizer Alpen

Zusammenfassung In der helvetischen Kreide scheint es also im ganzen so zu sein, daß die einfachen Rhythmen (Feinschichtung und Kalk-Mergel-Schichtwechsel) klimatisch, d. h. exogen, die Zyklen und Großzyklen tektonisch, d. h. endogen, begründet sind (3).     

Zeitgebundene Erzlagerstätten

Proceeding from the observation that in the Early Paleozoic there is a time-bound, world-wide distributed ore deposit type with scheelite in volcanic-sedimentary series, the question concerning a systematic development of ore deposits connected with an evolution of the earth's crust and mantle is discussed. A schematic model of this development is constructed, which, beginning with a still thin, primeval crust, by way of time-bound stages as for instance greenstone belts and mobile zones, receiving abundant material introduction from juvenile volcanism accompanied with corresponding time-bound ores, leads to the “Assynthic” revolution, giving rise to a crust which is essentially dependent on selfsupport by sedimentary reworking and palingenic magmatism. During the initial “juvenile” period as well as during the palingenic there is significant participation of sedimentary processes, in dependence upon time-bound evolution of the atmosphere and biosphere, for material transport, redeposition and renewed concentration. During the “palingenic” stage the crust is only episodically supplied with mantle material along world-wide volcanic, tectonic lineaments, whereby new ore types, for example the scheelite ores of the Early Paleozoic or the copper-molybdenum ores at the Mesozoic-Cenozoic transition, experience their time-bound formation.     

Single subduction zone for the generation of Devonian ophiolites and high‐P metamorphic belts of the Variscan Orogen (NW Iberia)

Within the Variscan Orogen, Early Devonian and Late Devonian high‐P belts separated by mid‐Devonian ophiolites can be interpreted as having formed in a single subduction zone. Early Devonian convergence nucleated a Laurussia‐dipping subduction zone from an inherited lithospheric neck (peri‐Gondwanan Cambrian back‐arc). Slab‐retreat induced upper plate extension, mantle incursion and lower plate thermal softening, favouring slab‐detachment within the lower plate and diapiric exhumation of deep‐seated rocks through the overlying mantle up to relaminate the upper plate. Upper plate extension produced mid‐Devonian suprasubduction ocean floor spreading (Devonian ophiolites), while further convergence resulted in plate coupling and intraoceanic ophiolite imbrication. Accretion of the remaining Cambrian ocean heralded Late Devonian subduction of inner sections of Gondwana across the same subduction zone and the underthrusting of mainland Gondwana (culmination of NW Iberian allochthonous pile). Oblique convergence favoured lateral plate sliding, and explained the different lateral positions along Gondwana of terranes separated by Palaeozoic ophiolites.     

Place and people: spatializing degrees of bonding and bridging social capital in Lisbon (Portugal)

GeoJournal - Broad academic interest in measuring social relationships within an urban context has grown over recent decades. Significant research attention is focused on where social synergies...     

Application of pyrolysis-GC/MS for rapid assessment of organic contamination in sediments from Barcelona harbor

Pyrolysis-GC/MS is advantageous as a tool for rapid sediment contamination assessment because of the small sample size required, minimal sample preparation and its ability to detect a wide variety of organic pollutants as well as naturally-occurring biological materials. Py-GC/MS was applied, together with determination of organic carbon, and major and minor element concentrations, to evaluate potentially contaminated sediments in the port of Barcelona (Spain) and the adjacent Llobregat River delta. Detected contaminant markers, most evident in the Old Port (Port Vell) area, included hopanes and alkylated PAHs (petroleum), sterenes (sewage), C₁₆–C₁₉ phenylalkanes (detergents) and parent PAHs (combusted fuels).     

Paleobotany of Wisconsinan interstadials, eastern Great Lakes region, North America

This study concerns the pollen and plant macrofossils from Mid-Wisconsinan Interstadial sites within the Wisconsinan ice margin in eastern North America. The time period covered is from about 55,000 years BP to 22,500 years BP, an interval much longer than the postglacial. Sediments examined are principally those of large lakes deposited in the Erie and Ontario basins during intervals of ice retreat.The Port Talbot I Interval (from about 55,000 to 50,000 years BP) in the Erie basin is characterized by pollen assemblages alternating from Pinus-dominated zones to ones with abundant Pinus, Quercus, and nonarboreal pollen. These assemblages are interpreted as indicating relatively warm and dry conditions. Mean July temperatures fluctuated between 15 and 21°C.During the succeeding Port Talbot II Interval and Plum Point Interstadial, in both the Erie and Ontario basins, pollen assemblages are characterized by dominant Pinus and Picea. Characteristic macrofossils include needles of the boreal Picea and Larix and leaves of species with a more northerly distribution, such as Dryas integrifolia, Betula glandulosa var. glandulosa, Vaccinium uliginosum var. alpinum, and Salix herbacea. These fossil assemblages are interpreted as indicating cooler and moister conditions in a forest-tundra environment. Mean July temperatures fluctuated between 10 and 15°C during the Port Talbot II Interval and Plum Point Interstadial.     

On steep isogradic surfaces in the Simplon area

The Simplon tunnel (19.7 km long) in the Central Alps crosses, at an altitude of 640–700 m, a mountain chain that culminates in Monte Leone (3 553 m). Along the tunnel axis the metamorphic grade of Mesozoic sediments, recrystallized during the Lepontine phase of the Alpine orogenesis, increases from NW to SE. Investigations on rock samples from the tunnel and from surface exposures give information in three dimensions on conditions during the culmination of Alpine regional metamorphism in the Simplon group. The succession of isograds from km 3 from the NW entrance of the tunnel in SE direction is: First occurrence of biotite, of garnet, last occurrence of albite in paragenesis with calcite, entry of feldspars of the peristerite gap and of oligoclase alone in calc-schists, marbles and amphibolites, coming in of plagioclase An > 30 associated with calcite, first occurrence of staurolite and kyanite, entry of tremolite and calcite, occurrence of plagioclase An >50 in calcschists. Correlation of the data from tunnel and surface samples shows that, in the northwestern and central part of the section, the isogradic surfaces are steeply inclined to the NW, the average dip is 60–75°, with uncertainty between 55 and 90°. In the southeastern part of the section the isogradic surfaces are overturned and dip to the E. No observations indicate gently inclined isogradic surfaces. Geological evidence excludes postmetamorphic tilting of originally subhorizontal isogradic surfaces in such a scale. It is assumed that, during the Lepontine phase, the isobaric surfaces have been subhorizontal, but that the isotherms (which roughly correspond to isograds) have formed angles greater than 45° with isobars. During the culmination of metamorphism vertical and lateral temperature gradients differed considerably from place to place in the Simplon area, and gradually changed also in one and the same direction. The Simplon area is situated near the western edge of the high-grade metamorphic zones of the Ticino complex. The metamorphic conditions described are believed to have been strongly influenced by the eastern adjacent vast thermal bulge of the Central Alps. Thus, not only in Val Bregaglia, with its quite different geological environment, at the E end of the highgrade zone and of the same thermal antiform, but also in the Simplon area in the W, isogradic surfaces are steeply inclined.