Resistivity response to the porosity and permeability of low rank coal

Laojunmiao coal samples from the eastern Junggar basin were studied to understand the relationship between coal resistivity and the physical parameters of coal reservoirs under high temperatures and pressures.Specifically,we analysed the relationship of coal resistivity to porosity and permeability via heating and pressurization experiments.The results indicated that coal resistivity decreases exponentially with increasing pressure.Increasing the temperature decreases the resistivity.The sensitivity of coal resistivity to the confining pressure is worse when the temperature is higher.The resistivity of dry coal samples was linearly related to φ~m.Increasing the temperature decreased the cementation exponent(m).Increasing the confining pressure exponentially decreases the porosity.Decreasing the pressure increases the resistivity and porosity for a constant temperature.Increasing the temperature yields a quadratic relationship between the resistivity and permeability for a constant confining pressure.Based on the Archie formula,we obtained the coupling relationship between coal resistivity and permeability for Laojunmiao coal samples at different temperatures and confining pressures.     

煤层气排采时渗透率动态特征研究

正确认识煤层气井开采过程中的渗透性变化特征是实现煤层气科学高效开发的重要前提.目前,大量的室内实验研究渗透率随排采的变化时仅考虑压力敏感性,而没有考虑在实际生产过程中存在的基质收缩效应的影响.笔者提出一种动态分析方法,利用实际生产数据,分段拟合出不同生产时间下的煤层参数,包括渗透率和地层压力等,并且在前人研究的基础上建立了考虑应力敏感效应和基质收缩效应的渗透率数学模型,通过数据回归获得到模型的具体参数.该方法可以用于描述煤层渗透率的动态特征,预测煤层气产量变化,指导现场配产.     

反馈放大器的一种广义算法

本文介绍了反馈放大器的一种新的计算方法。本方法的特点是把四种类型的反馈放大器归纳为一类来计算。这是作者瓜熟蒂落 图使反馈放大器的分析和计算向着规范化统一化方向前进过程中所做的努力和尝试。     

低孔低渗气藏测井识别方法的应用研究

低孔低渗油气藏一直是储层测井评价中的一个难点问题。锦旗工区根据岩性、物性以及含油气性的关系,采用侵入特性、孔隙度曲线重叠、含气指示、声波速度比值等方法进行低孔低渗气藏的识别。锦旗地区面积大,气水关系复杂,应充分利用各种测井资料,采用多种方法开展流体性质分析,进行综合判别。从应用效果来看,孔隙度重叠,含气指示方法最为可靠。     

Mechanical property and permeability of raw coal containing methane under unloading confining pressure

Based on domestic-developed triaxial servo-controlled seepage equipment for thermal–hydrological–mechanical coupling of coal containing methane, an experimental study was carried out to investigate mechanical property and gas permeability of raw coal, under the situation of conventional triaxial compression and unloading confining pressure tests in different gas pressure conditions. Triaxial unloading confining pressure process was reducing confining pressure while increasing axial pressure. The research results show that, compared with the peak intensity of conventional triaxial loading, the ultimate strength of coal samples of triaxial unloading confining pressure was lower, deformation under loading was far less than unloading, dilation caused by unloading was more obvious than loading. The change trend of volumetric strain would embody change of gas permeability of coal, the permeability first reduced along with volumetric strain increase, and then raised with volume strain decrease, furthermore, the change trends of permeability of coal before and after destruction were different in the stage of decreasing volume strain due to the effect of gas pressure. When gas pressure was greater, the effective confining pressure was smaller, and the radial deformation produced by unloading was greater. When the unloading failed confining pressure difference was smaller, coal would be easier to get unstable failure.     

Reconstruction of different scales of pore-fractures network of coal reservoir and its permeability prediction with Monte Carlo method

There are millimeter, micron and nanometer scales of pores and fractures in coal to describe different scales of coal pores and fissures communicating path and to quantitatively characterize their permeability. Such information provides an important basis for studying coalbed methane output mechanism. The pores and fissures in a large number of coal samples were observed and counted by scanning electron microscopy and optical microscopy. The probability distribution models of pore-fissure network were then established. Different scales of pore-fissures 2D network models were reconstructed by Monte Carlo method. The 2D seepage models were obtained through assignment zero method and using Matlab software. The effect of permeability on different scale pore-fractures network was obtained by two-dimensional seepage equation. Predicted permeability is compared with the measured ones. The results showed that the dominant order of different scale pore-fractures connected path from high to low is millimeter-sized fractures, seepage pores and micron-size fractures. The contribution of coal reservoir permeability from large to small is millimeter-size fractures, micron-size fractures and seepage pores. Different parameters in different scale pore-fractures are of different influence permeability.Reconstruction of different scale pore-fractures network can clearly display the connectivity of porefractures, which can provide a basis for selecting migration path and studying gas flow pattern.     

考虑轴力扩散计算基础弯矩的方法

在计算柱下扩展基础、条形基础等应力时考虑柱轴力在基础中的扩散作用 ,使计算结果更合理 ,同时把扩展基础和刚性基础计算方法自然统一 ,推出了计算公式 ,便于实际应用     

计算非刚性基地的主轴部件静,动特性的传递矩阵法

本文将一般的传递矩阵法扩展于计算在非刚性基地上设置支承的主轴部件的动静、特性。根据支承地的动力学特点,建立了具有基地分支系统的新的力学模型;并导出整个系统的计算方法。实际主轴动特性的测量结果表明,基于新模型的计算结果与实测值有良好的吻合。     

预应力等效荷载计算的通用方法及其简化

应用微分几何曲线论基本公式,建立了张拉按抛物线布置的预应力筋引起的等效荷载计算的通用方法及通用方法的简化方法．经计算分析,给出了目前张拉预应力筋引起的等效荷载计算的常规方法的适用范围．为合理设计预应力混凝土转换梁等特色结构提供了部分参考．     

轴向均布荷载压杆稳定问题的重心插值配点法

用重心插值配点法对轴向均布荷载下压杆稳定问题进行了研究。采用重心Lagrange插值多项式建立未知函数的微分矩阵,采用配点法将压杆稳定问题的控制方程表示为代数方程组。通过求解代数方程组系数矩阵的特征值和特征向量,得到了精度很高的后屈曲挠度数值和临界载荷数值。实例证明,这种方法原理简单,易于程序实现。     

绉组织矩阵模型的建立及其CAD实现

通过随机方法建立了绉组织纹板矩阵与穿综矩阵,结合上机图矩阵关系得到了组织矩阵,讨论了绉组织上机图矩阵的CAD实现方法.对五片综和六片综绉组织的研究结果表明,随机方法可以方便地实现绉组织矩阵模型的建立,可以通过CAD快速实现不同交织规律的绉组织,可加速绉组织的设计过程并提高设计效率.     

Relationship between fracturing nominal stress and porosity for metal foams under biaxial tension

High porosity metal foams have been more and more extensively utilized owing to their excellent properties[1—7]. In order to select and use these materials more effectively and rationally, researchers have widely studied their mechanical characteristics, of which the tensile property is a very important index. As in the practical engineering structure, the applied loading is always multiaxial, it is necessary to investigate the biaxial and triaxial tensile properties. Based on our studies on …     

一种混凝土桥梁徐变的有效计算方法

为了研究由徐变、收缩引起的变形对桥梁结构的影响,以力的增量形式推导出计算各施工阶段徐变次内力、徐变变形的递推公式,同时将本文的递推公式和传统的位移增量递推公式分别编制计算程序,利用有限元原理就奉化江大桥的施工结束阶段时徐变次内力和徐变变形进行模拟计算,并对两种计算结果进行了比较,提出一种有效计算混凝土桥梁徐变效应的方法.     

产品方案设计约束模型及其演化博弈算法求解

针对产品方案设计这一有约束的系统求解问题,通过分析产品方案设计在概念与特性上与约束满足问题(CSP)的相似性,将方案求解问题映射到CSP中来表示方案设计,对应CSP中的变量、变量的域和约束集建立产品方案设计CSP模型.采用演化博弈算法求解CSP模型,将方案设计求解问题的搜索空间映射为博弈的策略组合空间,将评价函数映射为博弈的效用函数.通过主体的顺序最优反应达到均衡状态,并不断对均衡状态施加扰动再重新恢复均衡,从而搜寻到更优的均衡状态,最终达到对应于全局最优解的Pareto最优均衡状态.以透平膨胀机的方案设计为例验证了所提理论和方法的可行性和有效性.     

地铁管片抗裂度及裂缝宽度试验和计算方法

为了研究钢筋混凝土衬砌管片的开裂性能,对2片 1:1 不同配筋率的钢筋混凝土衬砌管片进行了试验。研究发现,配筋率的提高对钢筋混凝土衬砌管片抗裂度的影响十分有限,随着配筋率的提高平均裂缝间距、最大裂缝宽度减小,但减小幅度不大。根据试验结果,分析了不同配筋率对钢筋混凝土衬砌管片抗裂度和裂缝宽度的影响,给出了考虑衬砌管片高度影响的抗裂度及考虑配筋率影响的最大裂缝宽度实用计算公式,理论计算结果与试验数据吻合良好。     

对称次反对称矩阵反问题的最小二乘解

讨论了对称次反对称矩阵反问题的最小二乘解,得到了解的具体表达式。并讨论了用对称次反对称矩阵构造给定矩阵的最佳逼近问题,给出该问题有解的充分必要条件和解的表达式。     

环形腔激光器加速寿命试验和特征寿命的计算

恒应力加速寿命试验是快速获得电子元器件失效数据、测量其寿命的有效方法.将该方法用于环形腔He-Ne激光器产品,根据环形腔激光器失效概率试验数据的分布特征,提出了一种先验分布函数,并由加速寿命方程出发,导出了计算环形腔激光器特征寿命的公式.对环形腔激光器产品试验数据进行了处理,精确地估算出环行激光器产品的寿命,极大地缩短了试验周期.     

考虑竖向地震动下模量比和阻尼比简化公式

为了满足抗震规范和工程应用上的需要,提出便于工程应用的简化计算方法来考虑竖向地震动对动剪切模量和阻尼比的影响非常必要.根据考虑竖向地震动对土体最大剪应变相对增量影响的回归方程,建立考虑竖向地震动与土体动剪切模量比和阻尼比变化之间的简化计算公式.分析结果可以看出,加竖向地震动后使动剪切模量比减少,阻尼比增大,而无论增大还是减小都是非线性的,随剪应变幅值的增大,加竖向后模量比减小百分比逐渐变大,阻尼比增大百分比逐渐变小,随输入加速度峰值增大,影响也越大.竖向地震动对动剪切模量比在小应变时影响不大,大应变时影响较大,减小百分比最大可达17%,竖向地震动对阻尼比在大应变时影响不大,小应变时影响较大,增大百分比最大可达16%.     

修正的矩阵正交化方法及其偏导数

矩阵正交化过程普遍采用的足经典的施密持正交化方法．文章对施密特正交化过程进行修正,且给出了变量矩阵施密特正交化过程的偏导数,能满足某些数值算法的需要。     

异面绉组织矩阵的设计与计算机实现

为了加快异面绉组织的设计过程,提出了一种基于随机分组法的异面绉组织纹板矩阵和穿综矩阵生成方法.对十片综绉组织纹板矩阵、穿综矩阵的构造过程进行了分析,并运用计算机验证了所提出方法的有效性.研究结果表明,提出的异面绉组织矩阵的设计方法可以快速产生效果较好的异面绉组织.