Volatility of Bitumen Prices and Implications for the Industry     

Emil D. Attanasi 《Natural Resources Research》2008,17(4):205-213

Sustained crude oil price increases have led to increased investment in and production of Canadian bitumen to supplement North American oil supplies. For new projects, the evaluation of profitability is based on a prediction of the future price path of bitumen and ultimately light/medium crude oil. This article examines the relationship between the bitumen and light crude oil prices in the context of a simple error-correction economic-adjustment model. The analysis shows bitumen prices to be significantly more volatile than light crude prices. Also, the dominant effect of an oil price shock on bitumen prices is immediate and is amplified, both in absolute terms and percentage price changes. It is argued that the bitumen industry response to such market risks will likely be a realignment toward vertical integration via new downstream construction, mergers, or on a de facto basis by the establishment of alliances.  相似文献   

The Rožná uranium deposit (Bohemian Massif, Czech Republic): shear zone-hosted, late Variscan and post-Variscan hydrothermal mineralization     

Bohdan Kříbek  Karel Žák  Petr Dobeš  Jaromír Leichmann  Marta Pudilová  Miloš René  Bohdan Scharm  Marta Scharmová  Antonín Hájek  Daniel Holeczy  Ulrich F. Hein  Bernd Lehmann 《Mineralium Deposita》2009,44(1):99-128

Three major mineralization events are recorded at the Rožná uranium deposit (total mine production of 23,000 t U, average grade of 0.24% U): (1) pre-uranium quartz-sulfide and carbonate-sulfide mineralization, (2) uranium, and (3) post-uranium quartz-carbonate-sulfide mineralization. (1) K–Ar ages for white mica from wall rock alteration of the pre-uranium mineralization style range from 304.5 ± 5.8 to 307.6 ± 6.0 Ma coinciding with the post-orogenic exhumation of the Moldanubian orogenic root and retrograde-metamorphic equilibration of the high-grade metamorphic host rocks. The fluid inclusion record consists of low-salinity aqueous inclusions, together with H₂O-CO₂-CH₄, CO₂-CH₄, and pure CH₄ inclusions. The fluid inclusion, paragenetic, and isotope data suggest that the pre-uranium mineralization formed from a reduced low-salinity aqueous fluid at temperatures close to 300°C. (2) The uraniferous hydrothermal event is subdivided into the pre-ore, ore, and post-ore substages. K–Ar ages of pre-ore authigenic K-feldspar range from 296.3 ± 7.5 to 281.0 ± 5.4 Ma and coincide with the transcurrent reorganization of crustal blocks of the Bohemian Massif and with Late Stephanian to Early Permian rifting. Massive hematitization, albitization, and desilicification of the pre-ore altered rocks indicate an influx of oxidized basinal fluids to the crystalline rocks of the Moldanubian domain. The wide range of salinities of fluid inclusions is interpreted as a result of the large-scale mixing of basinal brines with meteoric water. The cationic composition of these fluids indicates extensive interaction with crystalline rocks. Chlorite thermometry yielded temperatures of 260°C to 310°C. During this substage, uranium was probably leached from the Moldanubian crystalline rocks. The hydrothermal alteration of the ore substage followed, or partly overlapped in time, the pre-ore substage alteration. K–Ar ages of illite from ore substage alteration range from 277.2 ± 5.5 to 264.0 ± 4.3 Ma and roughly correspond with the results of chemical U–Pb dating of authigenic monazite (268 ± 50 Ma). The uranium ore deposition was accompanied by large-scale decomposition of biotite and pre-ore chlorite to Fe-rich illite and iron hydrooxides. Therefore, it is proposed that the deposition of uranium ore was mostly in response to the reduction of the ore-bearing fluid by interaction with ferrous iron-bearing silicates (biotite and pre-ore chlorite). The Th data on primary, mostly aqueous, inclusions trapped in carbonates of the ore substage range between 152°C and 174°C and total salinity ranges over a relatively wide interval of 3.1 to 23.1 wt% NaCl eq. Gradual reduction of the fluid system during the post-ore substage is manifested by the appearance of a new generation of authigenic chlorite and pyrite. Chlorite thermometry yielded temperatures of 150°C to 170°C. Solid bitumens that post-date uranium mineralization indicate radiolytic polymerization of gaseous and liquid hydrocarbons and their derivatives. The origin of the organic compounds can be related to the diagenetic and catagenetic transformation of organic matter in Upper Stephanian and Permian sediments. (3) K–Ar ages on illite from post-uranium quartz-carbonate-sulfide mineralization range from 233.7 ± 4.7 to 227.5 ± 4.6 Ma and are consistent with the early Tethys-Central Atlantic rifting and tectonic reactivation of the Variscan structures of the Bohemian Massif. A minor part of the late Variscan uranium mineralization was remobilized during this hydrothermal event.  相似文献   

Petrology,genesis and geodynamic implication of the Mesoproterozoic–Late Cretaceous Timmasamudram kimberlite cluster,Wajrakarur field,Eastern Dharwar Craton,southern India     

Ashish Dongre  N.V. Chalapathi Rao  K.S. Viljoen  B. Lehmann 《地学前缘(英文版)》2017,8(3):541-553

New mineralogical and bulk-rock geochemical data for the recently recognised Mesoproterozoic(ca.1100 Ma) and late Cretaceous(ca.90 Ma) kimberlites in the Timmasamudram cluster(TKC) of the Wajrakarur kimberlite field(WKF),Eastern Dharwar Craton,southern India,are presented.On the basis of groundmass mineral chemistry(phlogopite,spinel,perovskite and clinopyroxene),bulk-rock chemistry(SiO_2.K_2O,low TiO_2.Ba/Nb and La/Sm),and perovskite Nd isotopic compositions,the TK-1(macrocrystic variety) and TK-4(Macrocrystic variety) kimberlites in this cluster are here classified as orangeites(i.e.Group Ⅱ kimberlites),with geochemical characteristics that are very similar to orangeites previously described from the Bastar Craton in central India,as well as the Kaapvaal Craton in South Africa.The remaining kimberlites(e.g.,TK-2,TK-3 and the TK-1 microcrystic variant),are more similar to other 1100 Ma,Group Ⅰ-type kimberlites of the Eastern Dharwar Craton,as well as the typical Group Ⅰkimberlites of the Kaapvaal Craton.Through the application of geochemical modelling,based on published carbonated peridotite/melt trace element partition coefficients,we show that the generation of the TKC kimberlites and the orangeites results from low degrees of partial melting of a metasomatised,carbonated peridotite.Depleted mantle(T_(DM)) Nd perovskite model ages of the 1100 Ma Timmasamudram kimberlites show that the metasornatic enrichment of their source regions are broadly similar to that of the Mesoproterozoic kimberlites of the EDC.The younger,late Cretaceous(ca.90 Ma) TK-1(macrocrystic variant)and TK-4 kimberlites,as well as the orangeites from the Bastar Craton,share similar Nd model ages of1100 Ma,consistent with a similarity in the timing of source enrichment during the amalgamation of Rodinia supercontinent.The presence of late Cretaceous diamoncliferous orangeite activity,presumably related to the location of the Marion hotspot in southern India at the time,suggests that thick Iithosphere was preserved,at least locally,up to the late Cretaceous,and was not entirely destroyed during the breakup of Gondwana,as inferred by some recent geophysical models.  相似文献   

Prediction of capillary hysteresis in a porous material using lattice-Boltzmann methods and comparison to experimental data and a morphological pore network model     

B. Ahrenholz  J. Tölke  P. Lehmann  A. Peters  A. Kaestner  M. Krafczyk  W. Durner 《Advances in water resources》2008

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Thank you to 2022 Ocean Dynamics reviewers     

Ezer  Tal  Carniel  Sandro  Amin  Chabchoub  de Camargo  Ricardo  Estrada-Allis  Sheila N.  Gao  Guoping  Greatbatch  Richard J.  Lermusiaux  Pierre F. J.  Liu  Zhiyu  Miyazawa  Yasumasa  Forster  Alejandro Orfila  Panickal  Swapna  Phillips  Helen  Pinones  Andrea  Stanev  Emil  Volker  Christoph  Xu  Fanghua  Young  Emma 《Ocean Dynamics》2023,73(1):35-38

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Sources to the East Greenland Current and its contribution to the Denmark Strait Overflow     

Emil Jeansson  Sara Jutterström  Leif G. Anderson  E. Peter Jones  James H. Swift 《Progress in Oceanography》2008,78(1):12-28

Data from the East Greenland Current in 2002 are evaluated using optimum multiparameter analysis. The current is followed from north of Fram Strait to the Denmark Strait Sill and the contributions of different source waters, in mass fractions, are deduced. From the results it can be concluded that, at least in spring 2002, the East Greenland Current was the main source for the waters found at the Denmark Strait Sill, contributing to the overflow into the North Atlantic. The East Greenland Current carried water masses from different source regions in the Arctic Ocean, the West Spitsbergen Current and the Greenland Sea. The results agree well with the known circulation of the western Nordic Seas but also add knowledge both to the quantification and to the mixing processes, showing the importance of the locally formed Greenland Sea Arctic Intermediate Water for the East Greenland Current and the Denmark Strait.  相似文献   

Anthropogenic carbon in the East Greenland Current     

Sara Jutterström  Emil Jeansson 《Progress in Oceanography》2008,78(1):29-36

Sections of dissolved inorganic anthropogenic carbon () based on 2002 data in the East Greenland Current (EGC) are presented. The has been estimated using a model based on optimum multiparameter analysis with predefined source water types. Values of have been assigned to the source water types through age estimations based on the transit time distribution (TTD) technique. The validity of this approach is discussed and compared to other methods. The results indicated that the EGC had rather high levels of in the whole water column, and the anthropogenic signal of the different source areas were detected along the southward transit. We estimated an annual transport of with the Denmark Strait overflow (σ_θ > 27.8 kg m⁻³) of ∼0.036 ± 0.005 Gt C y⁻¹. The mean concentration in this density range was ∼30 μmol kg⁻¹. The main contribution was from Atlantic derived waters, the Polar Intermediate Water and the Greenland Sea Arctic Intermediate Water.  相似文献   

Reply on the discussion by P. Routhier on: Molybdenum distribution in precambrian rocks of the Colorado mineral belt     

B. Lehmann 《Mineralium Deposita》1988,23(1):72-74

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S and the Structure of the Upper Mantle   总被引：1，自引：0，他引：1  

I. Lehmann 《Geophysical Journal International》1961,4(S0):124-138

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Simulation of long-term transient density-dependent transport in groundwater     

Emil O. Frind 《Advances in water resources》1982,5(2):73-88

A numerical model for the economical simulation of long-term transient response in density-dependent transport problems is introduced. Although a classical Galerkin finite element approach is used, emphasis on optimum efficiency throughout the development results in a scheme that is found to be significantly less costly than comparable existing schemes. This advantage in efficiency increases the scope of simulation problems that can be handled within the constraints of a limited research budget. Some distinctive aspects are the elimination of static quantities in the fluid continuity equation, achieved by the introduction of equivalent freshwater head, and the elimination of numerical integration, achieved by the deliberate choice of linear elements. As a result of this choice, fluid velocities are discontinuous across the element boundaries. It is shown, however, that the solution obtained with discontinuous velocities approaches that obtained with continuous velocities as the grid is refined, and that the two types of solutions give essentially the same results when the elements are in the same size range. The model is applied to simulate the complete transient response for a well-known problem of seawater intrusion in a confined aquifer. The simulation is performed with both the constant dispersion coefficient used by previous researchers, and a more physically realistic velocity-dependent dispersion coefficient. Responses are found to be substantially different for the two types of coefficients, with the velocity-dependent dispersion coefficient producing much slower convergence to a state of dynamic equilibrium, and a much more pointed saltwater toe, which at the bottom of the aquifer tends to a sharp interface at equilibrium. Finally, it is shown by means of large-scale applications that the model is capable of efficiently simulating the long-term transient response in systems of practical significance.  相似文献