System identification estimation of soil properties at the Lotung site

Dynamic properties of the soils at the Lotung test site, Lotung, Taiwan, are estimated from seismic vertical array measurements (input–output data sets) using both time-invariant and time-variant parametric modeling methods (system identification). Soil properties are directly mapped from model parameters to an equivalent lumped mass model of the soil interval. Shear stiffness and damping ratios were calculated for 8 events with M_L ranging from 4.5 to 7.0. Shear stiffness ranged between 0.5 and 6 MN/m, inversely proportional to PGA. The equivalent viscous damping ratio varied from 2 to 30% of critical damping, proportional to PGA. Degradation of soil behavior, while less pronounced with increasing depth, consistently occurs above a peak input acceleration of 0.07 g. Although “non-linear” behavior is evident above 0.17 g, Event 7 (0.21 g) is accurately predicted using a linear constant parameter model estimated from the smaller Event 8 aftershock ground motions.     

Continuous Multi‐probe Measurements in Fastflowing Waters Using a Hydrographic Slot

Taking continuous spatiotemporal in situ measurements with multi‐probes in fast‐flowing waters/rivers can be problematic because the sensors may be damaged by high shear forces and flotsam. To protect the multi‐probe and to enable easy access for the maintenance and calibration of the sensors, a special multi‐probe holder fixed in a hydrographic slot was developed. The validation of the probe system revealed a “memory effect” at short time scales (< 10 s) within sharp gradients caused by the overflow container of the multi‐probe rack keeping the sensors submerged in the sample water. Continuously recorded data (conductivity, temperature, pH, oxygen concentration and saturation, as well as in vivo fluorescence of chlorophyll‐a) from a research cruise on board the RV ALBIS along the river Elbe (river km 309) and entering the river Saale are presented. This river stretch upstream of the city of Magdeburg to the mouth of the Saale tributary was found to have a complex physicochemical character, which is attributable to the long mixing process of water from the river Saale and the river Elbe.     

Evaluation of one-dimensional in situ leaching processes

A methodology to characterizing processes of in situ leaching is developed to investigate various parameters that may affect the recovery of a valuable mineral and assure a successful application of the in situ leaching technology. The governing equations of in situ leaching processes for the one-dimensional case are solved both analytically and numerically for both the consumption rate of a lixiviant and the production rate of a target mineral. A numerical simulator, which is developed to evaluate coupled effects among leaching kinetics, solution flow and transport of the dissolved mineral species in saturated ore deposits, is validated against the steady-state solutions and applied to investigate the transient effects of various parameters on the mineral recovery. Results from the evaluation indicate that there exists an optimal flow velocity range of leach solution for the effective leaching of a particular ore deposit. The determination of this optimal leaching velocity may become a key to the design of a real in situ leach mine. Results of the parameter sensitivity study illustrate the relative importance of other parameters such as porosity, ore grade, and reaction rate. Copyright © 1999 John Wiley & Sons, Ltd.     

Metasomatic effects related to channelled fluid streaming through deep crust: fenites and associated carbonatites (In Ouzzal Proterozoic granulites, Hoggar, Algeria)

The In Ouzzal granulitic unit (IOGU) consists predominantly of felsic orthogneisses most of which correspond to granitoids emplaced during the Archaean, plus metasediments, including olivine-spinel marbles, of late Archaean age. All units were metamorphosed at granulite facies during the Eburnean (2 Ga). The stable isotope signature of the marbles (δ¹³C=–0.8 to –4.2‰/PDB; δ¹⁸O = 7.9 to 18.9‰/SMOW) does not record a massive streaming of C-bearing fluids during metamorphism. Most of the isotopic variation in the marbles is explained in terms of pregranulitic features. Metasomatic transformation of granulites into layered potassic syenitic rocks and emplacement of carbonate veins and breccias occurred during retrogressive granulite facies conditions. The chemistry of these rocks is comparable with that of fenites and carbonatites with high contents of (L)REEs, Th, U, F, C, Ba and Sr but, with respect to these elements, a relative depletion in Nb, Ta, Hf, Zr and Ti. The isotopic compositions of Nd (?Nd_(T)=–6.3 to –9.9), of Sr (⁸⁷Sr/⁸⁶Sr_(T)= 0.7093–0.7104), and the O isotopic composition of metasomatic clinopyroxene (δ¹⁸O = 6.9 to 8‰), all indicate that the fluid had a strong crustal imprint. On the basis of the C isotope ratios (δ¹³C =–3.5 to –9.7‰), the fluid responsible for the crystallization of carbonates and metasomatic alteration is thought to be derived from the mantle, presumably through degassing of mantle-derived magmas at depth. Intense interaction with the crust during the upward flow of the fluid may explain its chemical and isotopic signatures. The zones of metasomatic alteration in the In Ouzzal granulites may be the deep-seated equivalents of the zones of channelled circulation of carbonated fluids described at shallower levels in the crust.     

Gedrite–garnet–sillimanite-bearing granulites from Amessmessa area, south In Ouzzal, Hoggar, Algeria

Some granulites from the Amessmessa area (south In Ouzzal unit, Hoggar) contain the peak assemblage gedrite+garnet+sillimanite+quartz that was used to estimate the P–T conditions of metamorphism. The rocks developed symplectites and corona textures by the breakdown of the primary paragenesis to orthopyroxene, cordierite and spinel. The successive parageneses formed in separate microdomains according to a clockwise P–T path. Geothermometry, geobarometry and phase diagram calculations indicate that the textures formed by decompression and cooling from 7–9 kbar and 850–900°C to 3.5–4.5 kbar and 700–800°C. This P–T evolution is consistent with low to medium a_H2O, between 0.4 and 0.7, and is similar to the metamorphic conditions deduced in Al–Mg granulites from the north of In Ouzzal.     

水土流失对山地旅游地水体观光功能影响研究

水土流失影响山地旅游景观质量,成为当前山地旅游地普遍性的环境问题之一.通过土壤与水体浊度模拟实验表明,水土流失以改变水体浊度从而影响景观观光质量,20NTU浊度可作为次降雨水土流失对水体景观影响的临界值.以浙江省天台县石梁景区实证研究得到,不同流域降雨侵蚀对水体浊度影响具有差异性,同一流域次降雨侵蚀对观光水体浊度影响受流域降水强度与降水量共同作用.     

交叉偶极子声测井多频率反演地层三阶弹性常数和地应力研究

基于声弹性理论,本文详细论述了利用交叉偶极子多频率相速度反演地层三阶弹性常数和地应力的理论及信噪比对反演结果的影响.定性和定量分析表明在速度应力方程中,不含三阶弹性常数项与含三阶弹性常数项相比对速度的影响可以忽略,由此只利用一次测井资料同时反演地应力和三阶弹性常数是一个严重病态的问题或一个不确定性问题.针对不同的反演模型,详细考察了信噪比对各自简化模型和精确模型反演结果的影响.数值模拟结果表明,利用一次测井采用精确模型反演全部四个参数方法受信噪比影响严重.而利用不同流体压力下的测井资料进行反演时可以采用简化模型取代精确模型以便简化计算和提高反演速度,因为简化模型和精确模型有着几乎相同的精度;同时,分步反演的方法可以较好地反演出原位地应力及三阶弹性常数.     

Combustion Kinetics of Athabasca Bitumen from 1D Combustion Tube Experiments

There are two basic requirements for heavy-oil recovery processes: first, mobilize the bitumen, and second, have a drive mechanism deliver the mobilized bitumen to a production wellbore. In situ combustion has the potential to be an important heavy-oil recovery method. Before design of in situ combustion recovery processes can start, it is necessary as a first step to understand the kinetics of various complex chemical reactions and determine kinetic constants associated with the reactions. Even with modern reservoir simulation capabilities, this is a significant challenge. In this research, an Athabasca bitumen combustion tube experiment, conducted by the ISC Research Group at the University of Calgary, was history matched by using a reservoir thermal simulator to determine a set of kinetic parameters as well as the transport parameters for the system. The main results of the history match was a match of air injection rate, bitumen and gas production volumes, average product gas compositions, temperature profiles along the tube through time, and pressure. Gridding sensitivities were examined to determine if the derived kinetic and transport parameters were dependent on gridblock size. The results revealed that the grid was refined enough to sufficiently capture thermal, mass transfer, and reaction length scales. After this single match was achieved, the same constants were used to successfully predict several other combustion tube experiments. The results suggest that the fuel (coke) for high-temperature oxidation (HTO) originates mainly from low-temperature oxidation (LTO) and not from thermal cracking. This implies that the major control on HTO is upstream oxygen transfer into the LTO region. If LTO does not occur, then a relatively small amount of coke is deposited in the matrix due to thermal cracking and this may be insufficient to start or sustain HTO.     

浅谈铟、镉在大厂矿田的分布及综合回收前景

大厂矿田锡石硫化物矿床中产出的富铟铁闪锌矿为世界所罕见,文章探讨该类型矿床铟、镉的分布规律,分析计算该金属保有地质储量及年产量,简介当前回收情况及展望综合回收前景.