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41.
传统认为TSR成因的固态沥青(焦沥青)属于热化学反应的终端产物,不会对TSR的反应进程起到重要作用.本文以活性炭作为固态沥青(焦沥青)的模型化合物,开展了CaSO4-C-H2O体系的热模拟实验研究,探讨了CaSO4-C-H2O体系发生TSR的热力学特征.实验结果表明,CaSO4-C-H2O体系在300℃时即可启动TSR,主要生成CaCO3、H2S和CO2等产物.这一TSR门限温度要远低于以往室内利用气态或液态烃类进行的TSR模拟实验温度范围,与热力学计算结果一致.利用HSC Chemistry 5.0软件进行TSR过程模拟,发现25~200℃时CaSO4-C-H2O体系发生的TSR完全受动力学控制,在温度保持不变情况下,压力增大不利于CaSO4-C-H2O体系发生TSR.较少的含水量对TSR有一定促进作用,而含水量过多则可能抑制TSR的进行,含水量对TSR的影响可能与CaSO4在水中的饱和浓度有关.在一定的温度下,当体系pH≤2时,随着pH逐渐降低,CaSO4的量呈线性递减,但在沉积盆地地层水pH范围内(pH>4),pH对TSR的作用可以忽略不计.CaSO4-C-H2O体系发生的TSR反应是一个放热过程,并且随着温度升高,反应热逐渐增大.在25~200℃范围内,TSR反应热为12.9~133 J/molCaSO4.热力学计算以及模拟实验结果均暗示,固态沥青(焦沥青)可能比烃类更容易参与TSR. 相似文献
42.
43.
Chris Harris H. Stuart Smith Anton P. le Roex 《Contributions to Mineralogy and Petrology》2000,138(2):164-175
We have measured the δ18O values of the major phenocrysts (olivine, clinopyroxene and plagioclase) present in lavas from Tristan da Cunha and Gough
Island. These islands, which result from the same mantle plume, have enriched radiogenic isotope ratios and are, therefore,
prime candidates for an oxygen isotope signature that is distinct from that of MORB. Consistent differences between the δ18O values of olivine, pyroxene and feldspar in the Gough lavas show that the phenocrysts in the mafic Gough Island lavas are
in oxygen isotope equilibrium. The olivines in lavas with SiO2 <50 wt% have a mean δ18O value of 5.19‰, consistent with crystallization from a magma having the same oxygen isotope composition as MORB. Phenocrysts
in all the Gough lavas show a systematic increase in δ18O value as silica content increases, which is consistent with closed-system fractional crystallization. The lack of enrichment
in δ18O of the Gough magmas suggests that the mantle source contained <2% recycled sediment. In contrast, the Tristan lavas with
SiO2 >48 wt% contain phenocrysts which have δ18O values that are systematically ∼0.3‰ lower than their counterparts from Gough. We suggest that the parental mafic Tristan
magmas were contaminated by material from the volcanic edifice that acquired low δ18O values by interaction with water at high temperatures. The highly porphyritic SiO2-poor lavas show a negative correlation between olivine δ18O value and whole-rock silica content rather than the expected positive correlation. The minimum δ18O value occurs at an SiO2 content of about 45 wt%. Below 45 wt% SiO2, magmas evolved via a combination of assimilation, fractionational crystallization and crystal accumulation; above 45 wt%
SiO2, magmas appeared to have evolved via closed-system fractional crystallization.
Received: 23 November 1998 / Accepted: 27 September 1999 相似文献
44.
Marie Lionard Koenraad Muylaert Michle Tackx Wim Vyverman 《Estuarine, Coastal and Shelf Science》2008,76(4):809-817
In the upper Schelde estuary in 2002, phytoplankton biomass and community composition were studied using microscopic and pigment analyses. Chlorophyll a concentration was a good predictor of phytoplankton biomass estimated from cell counts and biovolume measurements. The phytoplankton carbon to chlorophyll a ratio, however, was often unrealistically low (<10). CHEMTAX was used to estimate the contribution of the major algal groups to total chlorophyll a. The dominant algal groups were diatoms and chlorophytes. While diatom equivalents in chlorophyll a predicted diatom biomass relatively well, chlorophyte equivalents in chlorophyll a were only weakly related to chlorophyte biomass. The pigment-based approach to study phytoplankton overestimated phytoplankton biomass in general and chlorophyte biomass in particular in late autumn and winter, when phytoplankton biomass was low. A possible explanation for this overestimation may be the presence of large amounts of vascular plant detritus in the upper Schelde estuary. Residual chlorophyll a, chlorophyll b and lutein in this detritus may result in an overestimation of total phytoplankton and chlorophyte biomass when the contribution of phytoplankton to total particulate organic matter is low. 相似文献
45.
Inter-annual variability in phytoplankton summer blooms in the freshwater tidal reaches of the Schelde estuary (Belgium) 总被引:1,自引:1,他引:0
Marie Lionard Koenraad Muylaert Abdel Hanoutti Tom Maris Michle Tackx Wim Vyverman 《Estuarine, Coastal and Shelf Science》2008,79(4):694-700
The inter-annual variability in phytoplankton summer blooms in the upper reaches of the Schelde estuary was investigated between 1996 and 2005 by monthly sampling at 10 stations. The large inter-annual variations of the chlorophyll a concentration in the freshwater tidal reaches were independent from variations in chlorophyll a in the tributary river Schelde. Summer mean chlorophyll a concentrations were significantly negatively correlated with flushing rate (Spearman correlation: r = −0.67, p = 0.05, n = 9) but not with temperature, irradiance and suspended particulate matter or dissolved silica (DSi) concentrations. During dry summers, low flushing rates permitted the development of dense phytoplankton populations in the upper part of the estuary, while during wet summers high flushing rates prevented the development of dense phytoplankton blooms. Flushing rate was also found to be important for the phytoplankton community composition. At low flushing rates, the community was dominated by diatoms that developed within the upper estuary. At high flushing rates, chlorophytes imported from the tributary river Schelde became more important in the phytoplankton community. The position of the chlorophyll a maximum shifted from the head of the estuary when flushing rates were low, to more downstream when flushing rates were high. Although DSi concentrations tended to be lower during years of high phytoplankton (mainly diatom) biomass, the relation with flushing rate was not significant. 相似文献
46.
Pham Thi Tuyet Nhung Do Thi Hoai Pham Tuan-Anh Thibaut Le Bertre Pierre Darriulat Pham Ngoc Diep Nguyen Thi Phuong Nguyen Thi Thao Jan Martin Winters 《天文和天体物理学研究(英文版)》2019,(3):97-110
Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better spatial resolution than previously available. They are analysed with emphasis on the de-projection in space of the effective emissivity and flux of matter using as input a prescribed configuration of the velocity field, assumed to be radial. The data are found to display an intrinsic axisymmetry with respect to an axis making a small angle with respect to the line of sight. A broad range of wind configurations, from prolate(bipolar) to oblate(equatorial) has been studied and found to be accompanied by significant equatorial emission. Qualitatively, the effective emissivity is enhanced near the equator to produce the central narrow component observed in the Doppler velocity spectra and its dependence on star latitude generally follows that of the wind velocity with the exception of an omni-present depression near the poles. In particular, large equatorial expansion velocities produce a flared disc or a ring of effective emissivity and mass loss. The effect on the determination of the orientation of the star axis of radial velocity gradients, and possibly competing rotation and expansion in the equatorial disc, is discussed. In general,the flux of matter is found to reach a broad maximum at distances of the order of 500 AU from the star.Arguments are given that may be used to favour one wind velocity distribution over another. As a result of the improved quality of the data, a deeper understanding of the constraints imposed on morphology and kinematics has been obtained. 相似文献
47.
Defining representative reservoir models usually calls for a huge number of fluid flow simulations, which may be very time-consuming. Meta-models are built to lessen this issue. They approximate a scalar function from the values simulated for a set of uncertain parameters. For time-dependent outputs, a reduced-basis approach can be considered. If the resulting meta-models are accurate, they can be called instead of the flow simulator. We propose here to investigate a specific approach named multi-fidelity meta-modeling to reduce further the simulation time. We assume that the outputs of interest are known at various levels of resolution: a fine reference level, and coarser levels for which computations are faster but less accurate. Multi-fidelity meta-models refer to co-kriging to approximate the outputs at the fine level using the values simulated at all levels. Such an approach can save simulation time by limiting the number of fine level simulations. The objective of this paper is to investigate the potential of multi-fidelity for reservoir engineering. The reduced-basis approach for time-dependent outputs is extended to the multi-fidelity context. Then, comparisons with the more usual kriging approach are proposed on a synthetic case, both in terms of computation time and predictivity. Meta-models are computed to evaluate the production responses at wells and the mismatch between the data and the simulated responses (history matching error), considering two levels of resolution. The results show that the multi-fidelity approach can outperform kriging if the target simulation time is small. Last, its potential is evidenced when used for history matching. 相似文献
48.
Gravity and S-wave modelling across the Jan Mayen Ridge,North Atlantic; implications for crustal lithology 总被引:1,自引:0,他引:1
Rolf Mjelde Inger Eckhoff Ståle Solbakken Shuichi Kodaira Hideki Shimamura Karl Gunnarsson Ayako Nakanishi Hajime Shiobara 《Marine Geophysical Researches》2007,28(1):27-41
The horizontal components from fourteen Ocean Bottom Seismometers deployed along four profiles focused along the western margin
of the Jan Mayen microcontinent, North Atlantic, have been modelled with regard to S-waves, based on P-wave models obtained
earlier. The seismic models have furthermore been constrained by 2D gravity modelling. High V
p/V
s-ratios (2.3–7.9) within the Cenozoic sedimentary section are attributed to significant porosities, whereas V
p/V
s-ratios in the order of 1.9–2.2 for the Mesozoic and Paleozoic sedimentary rocks indicate shale-dominated lithology throughout
the area. The eastern side of the Jan Mayen Ridge is interpreted as a passive, volcanic margin, based on relatively high crustal
V
p/V
s-ratios (1.9), whereas lower V
p/V
s-ratios (1.75–1.8) suggest the presence of intermediate composition crust and non-volcanic margin on the western side of the
ridge. In the westernmost part of the Jan Mayen Basin, slightly increased upper mantle V
p/V
s-ratios may indicate some degree of serpentization of upper mantle peridotites. 相似文献
49.
Poseidon-2 is the dual frequency, solid-state radar altimeter embarked on the CNES/NASA oceanographic satellite Jason-1. This article gives a brief summary of the instrument design and some in-flight performances. Flight results have confirmed the very good results of the altimeter transfer function, which is very stable, and that the range noise at instrument level is less than 2 cm for a Significant Wave Height of 2 m. 相似文献
50.