填料对地热井固井材料导热性能的影响

在地热井固井水泥中加入导热填料能够明显改善水泥石导热性能,提升地热井取热效果。在总结导热路径理论和紧密堆积理论的基础上,通过试验研究不同填料种类、粒径及掺量对固井水泥导热性能的影响。试验结果表明：较其他种类填料,石墨对水泥石导热性能提升效果最好;石墨粒径越大对应水泥石导热系数越高。不同粒径的石墨混合,较单一粒径石墨对水泥石导热性能的提升效果更好,其最优混合配比为：石墨粒径为150 μm与100 μm,质量比为2：1。随着石墨掺量增加,固井材料的导热系数逐渐增大,但流动度和48 h抗压强度逐渐降低。参照固井相关规范,提出固井材料中石墨掺量应控制在9%左右为宜。研究成果为地热井高导热固井材料的制备提供借鉴。移动阅读     

低频含水岩石介电高值成因及改进测量方法

含水岩石在低频下常常呈现高达104以上的介电常数值,数值模拟和实测结果都表明这是由于岩石中存在着传导电流,其具有与外场同相和正交的实、虚部,这二者通过与频率成反比的关系叠加在介电常数上.提出在平行板电容器一极板与被测岩石样品间夹入不导电薄膜的办法来消除传导电流的不利影响.对标准件的测量表明该方法的最大误差在4%以内.用该方法测量淡水饱和岩石样品,结果得到合理适中的介电常数值及清晰明了的介电极化谱.除湿岩石外,该方法还适用于冰、生物肌体等固态导电介质的介电谱研究.     

利用卫星遥感影像对多尺度专题图形数据库更新

利用PCI遥感图像处理软件，对QUICKBIRD和SPOT5遥感影像进行纠正、数据融合、线性增强，在MapINFO软件支持下，进行遥感图像与矢量数据同名点的配准，矢栅叠加，输出更新变化部分，进行外业调绘，根据调绘信息进行数据更新。     

半潜式贮油沉箱结构温度场计算分析

研究了多介质热传导问题。采用有限单元法对工程中的半潜式圆筒壳贮油沉箱夹层壳壁结构的温度场进行了计算分析。     

Estimating apparent thermal diffusivity of soil using field temperature time series

Reliable estimates of soil thermal properties such as heat capacity, thermal conductivity, and diffusivity are important in analysis of heat transmission through soils in applications such as shallow geothermal applications, buried electrical conduits, and in general heat/fluid flow analyses. A number of analytical, numerical and experimental methods are available to determine the soil thermal properties. In this paper, the analytical and numerical methods developed on the basis of one-dimensional heat conduction equation are used to estimate the apparent thermal diffusivity of soil. Three of the four analytical methods, Amplitude, Phase, and Arctangent provide explicit equations for the apparent thermal diffusivity. Two methods, Harmonic and Numerical, make use of large number of temperature measurements to implicitly solve for the apparent thermal diffusivity. The temperature time series data monitored at different depths in two field sites in Melbourne, Australia for more than 2 year period were used to estimate the apparent thermal diffusivity of soil down to 2 m depth. The apparent thermal diffusivity was calculated using all five methods and compared with laboratory experimental results. The effectiveness of each method in predicting the thermal diffusivity was compared and observed discrepancies were discussed. Finally, the observed soil temperature data for a 12 month period are used to model the temperature variation in the ground analytically using Harmonic method and the model prediction for the following 12 month was compared independently with the field measurements. The analytical model prediction is found to be in good agreement with the field monitored data.     

Sinusoidal oscillations radiating from a cylindrical source in thermal conduction or groundwater flow: Closed‐form solutions

The diffusion equation governs thermal conduction and groundwater flow phenomena. In this paper, we study the two‐dimensional radial propagation of a sinusoidal perturbation radiating from a cylindrical source within an infinite slab of homogeneous material. The solution of this problem has several applications. For instance, it can be used to determine the hydraulic diffusivity of the subsurface based on measurements of the hydraulic head around a vertical well during its development. For thermal problems, it can be used to determine the thermal diffusivity based on measurements of the temperature distribution around a cylindrical heat source generating a sinusoidal power per unit length. In this paper, we present a comprehensive analytical solution of this problem and we compare these solutions with numerical solutions. Two approximate analytical solutions, which can be relevant in practice, are also presented. Finally, we give an upper bound for the survival time of the transient part of the solution and we provide an estimate of the radius of influence of the sinusoidal solicitation. Copyright © 2010 John Wiley & Sons, Ltd.     

水合物钻井液微观结构热传导分形模型研究

[摘 要] 在水合物勘探开发过程中,钻井液除常规作用外,还必须具有抑制水合物分解与再生成 的作用。钻井液的这些宏观作用由其内部微观结构所决定,而水合物的分解和生成与介质的传热过程 有关。由于钻井液微观结构与多孔介质相似,故其传热过程也相似。利用多孔介质的性质及其传热理 论,系统分析了水合物钻井液微观结构与多孔介质的异同,探讨了水合物在钻井液中的分解特性。接着 阐述了分形理论,对钻井液微观结构的传热分形模型进行了研究。最后得出钻井液中水合物分解的传 热过程,建立了钻井液微观结构的一维热传导分形模型,并得出有效导热系数的分形表达式。     

The numerical modelling of advective transport in the presence of fluid pressure transients

Conventional modelling of transport problems for porous media usually assumes that the Darcy flow velocities are steady. In certain practical situations, the flow velocity can exhibit time‐dependency, either due to the transient character of the flow process or time dependency in the boundary conditions associated with potential flow. In this paper, we consider certain one‐ and three‐dimensional problems of the advective transport of a chemical species in a fluid‐saturated porous region. In particular, the advective flow velocity is governed by the piezo‐conduction equation that takes into account the compressibilities of the pore fluid and the porous skeleton. Time‐ and/or mesh‐refining adaptive schemes used in the computational modelling are developed on the basis of a Fourier analysis, which can lead to accurate and optimal solutions for the advective transport problem with time‐ and space‐dependent advective flow velocity distributions. Copyright © 2006 John Wiley & Sons, Ltd.     

Integral equation solution of heat extraction from a fracture in hot dry rock

In the study of heat extraction by circulating water in a fracture embedded in geothermal reservoir, the heat conduction in the reservoir is typically assumed to be one dimensional and perpendicular to the fracture. In this paper, we demonstrate that by an integral equation formulation utilizing Green's function, the multi‐dimensional heat flow in the reservoir can be modelled. In the resulting numerical solution system, the discretization of reservoir geometry is entirely eliminated, leading to a much more efficient scheme. The multi‐dimensional heat conduction effect as compared to its one‐dimensional simplification is studied. Copyright © 2001 John Wiley & Sons, Ltd.