DEM simulations of methane hydrate exploitation by thermal recovery and depressurization methods     

《Computers and Geotechnics》2016

Methane hydrate (MH, also called fiery ice) exists in forms of pore filling, cementing and load-bearing skeleton in the methane hydrate bearing sediment (MHBS) and affects its mechanical behavior greatly. To study the changes of macro-scale and micro-scale mechanical behaviors of MHBS during exploitation by thermal recovery and depressurization methods, a novel 2D thermo-hydro-mechanical bonded contact model was proposed and implemented into a platform of distinct element method (DEM), PFC2D. MHBS samples were first biaxially compressed to different deviator stress levels to model different in-situ stress conditions. With the deviator stress maintained at constant, the temperature was then raised to simulate the thermal recovery process or the pore water pressure (i.e. confining pressure for MH bond) was decreased to simulate the depressurization process. DEM simulation results showed that: during exploitation, the axial strain increased with the increase of temperature (in the thermal recovery method) or decrease of pore water pressure (in the depressurization method); sample collapsed during MH dissociation if the deviator stress applied was larger than the compression strength of a pure host sand sample; sample experienced volume contraction but its void ratio was slightly larger than the pure host sand sample at the same axial strain throughout the test. By comparison with the laboratory test results, the new model was validated to be capable of reproducing the exploitation process by thermal recovery and depressurization methods. In addition, some micro-scale parameters, such as contact distribution, bond distribution, and averaged pure rotation rate, were also analyzed to investigate their relationships with the macroscopic responses.  相似文献   

The behavior of a multilayered porous thermo-elastic medium with anisotropic thermal diffusivity and permeability     

《Computers and Geotechnics》2016

With the aid of integral transform techniques, this paper presents an extended precise integration solution for thermal consolidation problems of a multilayered porous thermo-elastic medium with anisotropic thermal diffusivity and permeability due to a heat source. From the fundamental governing equations, ordinary differential equations are derived by employing Laplace–Hankel transforms. By applying the extended precise integration method, equations in the transformed domain can be solved, and the actual solutions are further obtained by adopting a numerical inverse transformation. The accuracy and feasibility of the proposed theory is demonstrated by contrastive analysis with existing studies. Finally, several examples are carried out to investigate the influence of heat source’s type, axial distance, burial depth of heat source, ratio of thermo-permeability, permeability anisotropy, thermal diffusivity anisotropy and stratification on the thermal consolidation process.  相似文献   

Characterisation of carbonate minerals from hyperspectral TIR scanning using features at 14 000 and 11 300 nm     

D. Green  M. Schodlok 《Australian Journal of Earth Sciences》2016,63(8):951-957

Rapid characterisation of carbonate phases in hyperspectral reflectance spectra acquired from drill core material has important implications for mineral exploration and resource modelling. Major infrared active features of carbonates lie in the thermal region around 6500 nm, 11 300 nm and 14 000 nm, with the latter two features being most useful for differentiating mineral species. A scatter diagram of the wavelength of the 14 000 nm feature vs that of the 11 300 nm feature, powerfully differentiates carbonates. Although the wavelength of the 11 300 nm peak is easily measured, the 14 000 nm trough and peak are commonly weak and their wavelengths can confidently be used only after filtering the spectra, e.g. selecting only those with the trough and peak separated by 175–230 nm, typical of common carbonates. The method is demonstrated with drillhole 120R from the Rosebery polymetallic VHMS deposit in western Tasmania, which has been scanned with the HyLogger-3 system. A 14 000–11 300 plot shows a high degree of clustering of the drillhole 120R data close to the library spectra of calcite, dolomite, Fe-dolomite, ankerite, kutnohorite, rhodochrosite, Fe-rhodochrosite and siderite. The interpreted compositions of the carbonate spectral populations strongly correlate with the chemical populations of 144 analysed carbonates and provide a highly resolved spatial framework for interpreting carbonate alteration.  相似文献   

低温低压条件下辉石粉末的热导率实验分析:对月球及火星表面热环境研究的指示   总被引：1，自引：0，他引：1  

于雯  李雄耀  王世杰 《岩石学报》2016,32(1):99-106

在真空条件下矿物粉末热导率的实验测量,可为我们研究月球及行星表面的热属性和热演化,解译热红外和微波探测数据,开展月球及行星探测载荷设计提供重要的数据参数。本研究主要采用改造后的Hot Disk TPS 2500S导热仪对辉石粉末的热导率进行测量。同时,分析了真空度、温度对辉石粉末热导率的影响。实验结果表明:1)热导率随着真空度的降低呈下降趋势,大气压力在1000Pa时,辉石粉末热传导机制发生明显改变。在低压条件下(1000Pa)热导率随真空度的变化趋于平缓;2)辉石粉末热导率随温度的升高而增大,但是增大的幅度在低压和常压条件下存在明显差异。根据实验结果,提出了低压条件下辉石粉末热导率随真空度和温度变化的关系式。本研究表明,在月球和火星表面热环境的研究中,温度和压力对热导率的影响程度是不同的。上述结果对未来开展地外样品的热导率测量提供了重要的参考。  相似文献   

河北牛驼镇地热田高温地热水成因分析   总被引：1，自引：0，他引：1  

王永波  丁文萍  田月  王婧  丁蕊 《城市地质》2016,(3):59-64

牛驼镇地热田以基岩热储层最优,是目前地热田开发利用条件最好的热储层。牛驼镇基岩热储水温60℃~100℃,顶板埋深最浅处小于500m,一般为800~1500m,涌水量50~110 m3/h。基岩地热水水化学类型为Cl—Na型水,偏硅酸浓度46~92mg/L,偏硼酸浓度5.0~33 mg/L,氟浓度5.41~11 mg/L,是优质的理疗矿泉水。本文着重从构造运动的角度分析了牛驼镇高温地热水的形成。阐述了自元古代的吕梁运动开始至二叠纪期间,研究区在经过"三降两升"的五个地史发展期中不仅沉积了良好的基岩热储层,亦储藏了丰富的水源。随着新生代喜山运动的活跃,在牛东等断裂的控制下,牛驼镇凸起发育成熟,在此过程中,牛驼镇凸起暴露地表,沉积了新近系和第四系,构成基岩热储的良好盖层。另外,由于基岩热储岩性的热导率较高及埋藏深度较浅,使得牛驼镇地热田拥有相对较高温度的地热水资源。  相似文献   

基于Neuman井流理论确定玄武岩潜水含水层渗透系数的应用——以吉林靖宇煤矿为例          下载免费PDF全文

段乃金  陈刚  候海巅  徐建 《山东国土资源》2016,32(10)

全面分析研究区玄武岩潜水含水层水文地质条件的基础上,对稳定流和非稳定理论确定潜水含水层渗透系数的优缺点进行了对比,认为非稳定井流公式确定玄武岩潜水含水层渗透系数是合理的。Aquifer Test软件基于Neuman井流理论配线法求参原理,运用计算机完成了自动求参,避免了人工配线的不足。该文根据吉林靖宇煤矿研究区玄武岩潜水含水层非稳定流抽水试验,分别用Aquifer Test软件和稳定井流公式进行了求参,并对比分析得出:玄武岩含水层弹性释水作用影响时间较长,利用Neuman潜水井流公式求参可靠,且更逼近现实;用Aquifer Test软件实现了自动求参,具有操作简单规范、可比性好的优点。  相似文献   

Leachate studies on fly ash-stabilised expansive clay liners     

M. Uma Shankar 《Geomechanics and Geoengineering》2016,11(2):114-118

This paper presents leachate studies on fly ash-stabilised expansive clay liners. Fly ash in different contents (0%, 10%, 20% and 30%) by dry weight of the expansive clay was added to the clay, and the ash-clay blend was compacted as a liner overlying a compacted lateritic clay layer. Deionised water (DIW) and calcium chloride (CaCl₂) solutions of varying concentration (5 mM, 10 mM, 20 mM, 50 mM, 100 mM and 500 mM) were used as the permeating fluids in the leachate studies. Chemical analysis of the leachate was performed. For a given CaCl₂ concentration, the concentrations of both calcium ion and chloride ion in the leachate decreased up to a fly ash content of 20%, and thereafter they increased when the fly ash content was increased to 30%. Further, for a given fly ash content, concentrations of calcium ion and chloride ion increased with increasing CaCl₂ concentration.  相似文献   

Geotechnical Hybrid Simulation to Investigate the Effects of the Hydraulic Conductivity on One-Dimensional Consolidation Settlement     

Youngcheul Kwon 《Marine Georesources & Geotechnology》2016,34(3):219-233

Difficulties in the prediction of time-distribution of consolidation settlement will be introduced by using the Murayama test embankment case of Japan. In particular, it will be discussed why the prediction of consolidation rate is difficult in multi-layered soil with complex and variable mechanical properties like organic soil or peat. It can be inferred that uncertainties, which are embedded intricately in the consolidation problem as well as given ground condition, would be major causes for consolidation settlement. After that, the author focused on the movement of pore water under the various conditions of hydraulic conductivity in the soils, and how it can affect the time-distribution of the consolidation settlement. For the applied key methodology on the consolidation settlement problem, we propose the hybrid consolidation simulation controlling the movement of pore water with high accuracy and, finally, the aim of this article is to discuss the methodological approaches obtained by the study, including the basic concept and accurate movement of pore water under various conditions of soil layers and hydraulic conductivity.  相似文献   

长春地区粉质黏土导热系数与其物性参数相关性研究     

姚仁  杜立志  吕守航  沈明燮 《世界地质》2018,37(3):976-981

为研究导热系数与影响因素之间的相关关系,建立导热系数的推算公式,以长春地区粉质黏土为研究对象,对原状土样的导热系数与其物理参数之间的相关性进行回归分析。制作9个重塑土样,测其相关的参数值,以验证回归方程的适用性。结果表明,回归分析建立导热系数与2个物理参数之间的关系式不成立;考虑天然密度、含水率和孔隙度为自变量,其分别对应的相关性系数T检验显著值(Sig)都0. 05,复决定系数为0. 886,建立的回归方程成立,自变量能准确解释因变量的变化,且含水率与导热系数呈负相关,天然密度和孔隙度呈正相关。重塑土样相关参数代入回归方程得到的导热系数值与实验实测值之间相对误差低于4%,验证了该回归方程的普遍性和适用性。  相似文献   

Hydrothermal Dolomite: A Review and PerspectiveEI北大核心CSCD     

Li Q.  Bao Z. 《大地构造与成矿学》2018,(4):699-717

Hydrothermal dolomite commonly closely associates with oil-gas reservoirs and sediment-hosted Pb-Zn deposits, the Mississippi Valley-type (MVT) Pb-Zn deposits in particular. Host rocks of MVT deposits usually experienced extensive dolomitization, and indeed, hydrothermal dolomite is considered as a useful prospective indicator for MVT mineralization. However, genetic link between the hydrothermal dolomitization and MVT Pb-Zn mineralization is a matter of debate. This paper briefly reviewed the nomenclature and research history of hydrothermal dolomite, introduced the major geological, geochemical characteristics, and distribution of hydrothermal dolomite, spatial and possibly genetic relationship between hdyrothermal dolomite and hdyrothermal ore deposits and oil-gas reservoirs based on case studies including the occurrence of hydrothermal dolomites in MVT deposits in Southwest China. The temporal and genetic relationships between dolomitizaiton and thermal sulfate reduction, sulfide precipitation and thus the location of ore mineralization well worthy more attention, and comprehensive geological and isotope geochemical and state of art in situ techniques will contribute to understanding of the genesis of hydrotherml dolomite and the spatially related ore deposits and oil-gas reservoirs. © 2018, Science Press. All right reserved.  相似文献