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981.
982.
以大量的测试为基础,从煤层生气性、储气性、渗透性及围岩封盖性等方面对陕西韩城北部矿区煤层气的形成条件进行了研究与评价;划分了各煤层生、储、渗、盖类型,为本区今后煤层气勘探开发提供了科学依据。 相似文献
983.
To accurately measure the pH, Eh, EC and temperature of groundwater retrieved from boreholes, a deep groundwater sampling
apparatus was developed which provided sensory measurements both in situ and in a flow-through cell at ground level. Under
a pressure of 1×106 Pa the in situ accuracy of the apparatus sensor was within the following limits: pH ±0.2, temperature ±0.1°C, Eh ±10 mV,
and EC ±2.4%. The measuring and sampling of deep groundwater from a borehole of more than 1000 m in depth was performed continuously
for 30 days. Values of pH were the same for the in situ sensor, the flow-through cell sensor and the laboratory measurements
of the sampled water. At the beginning of the sampling period, Eh values of the in situ sensor indicated deep groundwater
conditions. The apparatus is particularly useful for Eh measurement. Chemical composition and stable isotope ratios indicated
that the groundwater sampled from more than 1000 m depth was a connate water with a chemical composition slightly different
from seawater of the present time, and the groundwater retrieved from 800 m depth was a meteoric water. Natural radioactive
elements are thought to be the origin of the tritium in the groundwater retrieved from the 1000 m depth.
Received: 6 August 1996 / Accepted: 22 October 1996 相似文献
984.
M. Ramonet J. C. Le Roulley P. Bousquet P. Monfray 《Journal of Atmospheric Chemistry》1996,23(2):107-136
The aim of the 222Rn measurements during the airborne campaign TROPOZ II, was first to help in the interpretation of the photochemical studies, and secondly to furnish a data set of 222Rn in the troposphere, for validation of atmospheric transport models. In this paper we present the 222Rn measurements, and their simulation with a 3-D atmospheric transport model based on observed winds. The 222Rn was measured using the active daughters deposit technique with isokinetic aerosol sampling. We have obtained 44 measurements distributed between 65° North and 55° South, from 1 to 11 km height. In 25% of cases, we found relatively high concentrations (> 300 mBq·scm) of 222Rn in the high troposphere (>8 km). The results of 3D simulations and the calculations of back-trajectories allow us to find the origins of the high 222Rn concentrations. The transport model reproduced most of the observed synoptic variations, but it overestimates the concentrations which implies a vertical transport of excessive velocity. 相似文献
985.
依据全频域的Biot理论,推导了在Biot的流体饱和孔隙介质中,平面P波垂直井轴入时与井孔相互作用所产生的井内声压场的解析表达式.通过数值计算,对井内声压场出现的共振响应进行了分析.重点研究在不同频率段渗透率对井内声压的影响及偏离井轴记录时声压的变化.结果表明,在井内测量地震波声压,全频域都有明显影响;测量大于500HZ的地震信号,检波器偏离井轴放置以及方位不同的影响不能忽略;渗透率变化对井内声压的影响程度最大不超过弹性固体情况(零渗透率)下相应声压的1/5. 相似文献
986.
报道了自行设计的收集、吸附、吸收多级串联采样装置,成功地用于一次采集焦炉烟气中以三种形态存在的有机污染物。经GC/MS检测出293神有机污染物,其中71种为重点污染物。此项技术能够全面真实地反映焦炉烟气中全量多环芳烃和其它复杂有机污染物的状况。 相似文献
987.
“面型”岩石测量方法可成倍地减少样品采集量和分析工作量,大幅度降低了工作成本。增强了样品的代表性,并且能够消除“测网效应”,快速有效地查明区域或矿区地球化学特征以及矿化富集部位。 相似文献
988.
Identifying the Representative Elementary Volume for Permeability in Heterolithic Deposits Using Numerical Rock Models 总被引:1,自引:0,他引:1
Using a range of realistic 3D numerical lithofacies (dm-scale) models of ripple laminated sandstone intercalated with mudstone
we evaluate how single-phase permeability varies as a function of sample support. The models represent a range of mudstone
content which is typical for tidal deposits. Furthermore, the spatial distribution of flow barriers (i.e. mudstone) is not
random, but governed by sedimentological rules giving a variable anisotropy ratio as a function of mudstone content. Both
vertical and horizontal permeability are found to vary at small sample volumes, but these fluctuations reduce as the sample
volume increases. The vertical permeability increases while the horizontal permeability is nearly constant as a function of
sample support for small mudstone contents. For higher mudstone content, the horizontal permeability decreases while the vertical
permeability is nearly constant as a function of sample support. We propose a criterion, based on a normalised standard deviation,
to determine the Representative Elementary Volume (REV). The size of the REV is dependent on both the property measured (vertical
and horizontal permeability) and the correlation lengths of the lithological elements (i.e. lithofacies). Based on this we
identify three flow upscaling regimes that each require a different method for upscaling: (1) layered systems where the arithmetic
and harmonic averages are appropriate, (2) systems close to the percolation threshold where a percolation model should be
used, and (3) discontinuous systems where an effective medium method provides the best estimate of permeability. The work
gives, by using numerical experiments on a range of heterogeneous systems, a new insight in determination of the REV for permeability
at the lithofacies scale and its relation to sedimentological parameters. 相似文献
989.
Restoration interventions to combat land degradation are carried out in arid and semi-arid areas to improve vegetation cover and land productivity. Evaluating the success of an intervention over time is challenging due to various constraints (e.g. difficult-to-access areas, lack of long-term records) and the lack of standardised and affordable methodologies. We propose a semi-automatic methodology that uses remote sensing data to provide a rapid, standardised and objective assessment of the biophysical impact, in terms of vegetation cover, of restoration interventions. The Normalised Difference Vegetation Index (NDVI) is used as a proxy for vegetation cover. Recognising that changes in vegetation cover are naturally due to environmental factors such as seasonality and inter-annual climate variability, conclusions about the success of the intervention cannot be drawn by focussing on the intervention area only. We therefore use a comparative method that analyses the temporal variations (before and after the intervention) of the NDVI of the intervention area with respect to multiple control sites that are automatically and randomly selected from a set of candidates that are similar to the intervention area. Similarity is defined in terms of class composition as derived from an ISODATA classification of the imagery before the intervention. The method provides an estimate of the magnitude and significance of the difference in greenness change between the intervention area and control areas. As a case study, the methodology is applied to 15 restoration interventions carried out in Senegal. The impact of the interventions is analysed using 250-m MODIS and 30-m Landsat data. Results show that a significant improvement in vegetation cover was detectable only in one third of the analysed interventions, which is consistent with independent qualitative assessments based on field observations and visual analysis of high resolution imagery. Rural development agencies may potentially use the proposed method for a first screening of restoration interventions. 相似文献
990.