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微量陨石激光熔样稀有气体测定方法是一种可以在微米尺度上对几毫克陨石样品进行准确稀有气体同位素分析的方法,克服了传统全岩熔融法在测量时存在样品用量大、前处理过程复杂和样品稀有气体分布不均导致不同组分的宇宙射线暴露历史无法进一步区分等问题。但是由于该方法所用样品体积小和样品用量低,要求实验室具有超低本底的稀有气体提取系统,目前国内在微量陨石稀有气体分析技术方面尚处于起步阶段。本文采用金刚石激光样品窗成功研制了超低本底的气体提取系统,通过系统体积标定和天平称量误差、热本底、干扰元素、质量歧视及质谱灵敏度等参数的校正,在中国科学院地质与地球物理研究所建立了微量陨石激光熔样稀有气体测定方法,并对毫克级微量钙长辉长无球粒陨石Millbillillie粉末标样进行了稀有气体同位素含量和比值测定,计算获得准确一致的宇宙暴露年龄。该方法的建立,将为我国迅速发展的比较行星学和深空探测提供重要技术支撑。 相似文献
32.
An experimental study of single and two-phase fluid flow through fractured granite specimens 总被引:1,自引:2,他引:1
P. G. Ranjith 《Environmental Earth Sciences》2010,59(7):1389-1395
Triaxial tests on the two-phase flow of air and water through fractured granite specimens were performed to discover whether
the two-phase fluid flow within rock fractures was laminar or turbulent. The two-phase flow characterization was carried out
based on the macroscopic two-phase steady state flow model and the homogeneous steady state flow model. Rock specimens with
a single natural fracture (joint roughness coefficient, JRC < 10) were tested using two-phase, high pressure triaxial rig.
Experimental results show that the estimated Reynolds numbers for various inlet fluid pressures are well below 1000. The findings
of this study reveal that both single and two-phase flow through rock fractures (JRC < 10) can be characterized as laminar
flows at moderate inlet fluid pressures. However, for single-phase air flow, an increase in inlet air pressures may result
in the formation of turbulent flow. 相似文献
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The ultra-low permeability of shale reservoirs necessitates engineering applications such as hydraulic fracturing to enable the extraction of economically viable amounts of gas. In this process, a high-pressure fluid is injected into the reservoir to create a network of fractures. Proppants are solid, spherical, high-strength particles with size range between 8 and 140 mesh (105 μm–2.38 mm), which are injected into the reservoir simultaneously with fracturing fluid to prompt the opening of the fractures created, and they play a major role in the hydraulic fracturing process. As a result, appropriate management of proppants in shale reservoirs based on precise identification of their behaviour in shale reservoirs is necessary, because unexpected proppant performance or behaviour, commonly known as proppant damage mechanisms, can greatly reduce fracture conductivity. Therefore, it is essential to determine the major factors affecting proppant behaviour in order to maintain constant fracture conductivity. Numerous factors have been found in previous studies, and they can be summarized into three major groups: proppant properties, reservoir properties and hydraulic fracturing production, which affect proppant damage mechanisms. In the present paper, case studies have been provided on the determination of potential factors influencing proppant behaviour, followed by a discussion of their effects on fracture conductivity. The aim of this study is to present current opinions on potential factors influencing proppant behaviour based on a comprehensive literature review. 相似文献
34.
Bandara K. M. A. S. Ranjith P. G. Zheng W. Tannant D. D. De Silva V. R. S. Rathnaweera T. D. 《Acta Geotechnica》2022,17(11):4837-4864
Acta Geotechnica - Proppant crushing and embedment in hydraulically-induced fractures is a major drawback to the recovery of unconventional oil/gas and geothermal energy production. This study... 相似文献
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Finite element simulation of fluid flow in fractured rock media 总被引:1,自引:3,他引:1
Fluid dynamics models are used by the petroleum industry to model single- and/or multi-phase flow within fractured rock formations,
in order to facilitate extraction of fluids such as oil and natural gas, and in other areas of engineering to study groundwater
flow, as well as to estimate contaminant seepage and transport. In this paper, the numerical modelling software Comsol is used to simulate air and water flow through a specimen of granite with a single vertical fracture subjected to triaxial
loading conditions. The intent of the model is to simulate triaxial test findings on a rock specimen with a natural fracture.
Fluid flow is simulated at various confining and inlet pressures using the cubic law. Model results were in good agreement
with laboratory findings. Pressure distribution along the fracture and across the specimen are as expected with a near linear
pressure distribution along the length of the fracture. A drawdown effect on pressure distribution across the specimen in
the vicinity of the fracture is also observed. Pressure gradient was largely uniform; however, some localised zones of high
gradient along the fracture are observed. 相似文献
40.
Richa Shukla P. G. Ranjith S. K. Choi A. Haque Mohan Yellishetty Li Hong 《Rock Mechanics and Rock Engineering》2013,46(1):83-93
Acoustic emissions (AE) and stress–strain curve analysis are well accepted ways of analysing crack propagation and monitoring the various failure stages (such as crack closure, crack initiation level during rock failure under compression) of rocks and rock-like materials. This paper presents details and results of experimental investigations conducted for characterizing the brittle failure processes induced in a rock due to monocyclic uniaxial compression on loading of two types of sandstone core samples saturated in NaCl brines of varying concentration (0, 2, 5, 10 and 15 % NaCl by weight). The two types of sandstone samples were saturated under vacuum for more than 45 days with the respective pore fluid to allow them to interact with the rocks. It was observed that the uniaxial compressive strength and stress–strain behaviour of the rock specimens changed with increasing NaCl concentration in the saturating fluid. The acoustic emission patterns also varied considerably for increasing ionic strength of the saturating brines. These observations can be attributed to the deposition of NaCl crystals in the rock’s pore spaces as well some minor geo-chemical interactions between the rock minerals and the brine. The AE pattern variations could also be partly related to the higher conductivity of the ionic strength of the high-NaCl concentration brine as it is able to transfer more acoustic energy from the cracks to the AE sensors. 相似文献