Compressibility and permeability of sand–kaolin mixtures. Experiments versus non‐linear homogenization schemes

This study deals with the behaviour of mixtures of sand and saturated kaolin paste considered as composite materials made of permeable and deformable (with non‐linear behaviour) matrix (the kaolin paste) with rigid and impervious inclusions (the sand grains). Oedometric and permeability tests highlight the key role of the state of the clay paste, and show the existence of a threshold of sand grain concentration above which a structuring effect influences both compressibility and permeability. At the light of these experiments two homogenization schemes (with simplifying assumptions to make the problem manageable) are considered to model these two parameters. Qualitative and quantitative comparisons with experimental data point out their respective domain of interest and limitations: a tangent homogenization scheme is shown to be sufficient to describe the macroscopic properties for dilute sand concentration; above the concentration threshold, the structuring effect is captured by the new homogenization scheme developed in this paper. Copyright © 2010 John Wiley & Sons, Ltd.     

包裹体测温技术在高邮凹陷北斜坡戴南组油气成藏期中的应用

为确定高邮凹陷北斜坡戴南组油藏的成藏期次,采用流体包裹体测温技术,对研究区3口井的流体包裹体特征和均一温度进行了分析。结果表明,该区戴南组储层流体包裹体分为盐水包裹体和有机包裹体;均一温度呈1期连续分布,主峰温在90～100℃。根据包裹体均一温度、地层埋藏史和热史,推测该区戴南组油气成藏时对应的地质年代约为垛二段沉积末期。结合圈闭发育史和烃源岩生排烃史等分析,最终确定研究区戴南组为1期成藏,时间为垛二段沉积末期。     

Two‐scale modeling of solute dispersion in unsaturated double‐porosity media: Homogenization and experimental validation

A two‐scale modeling of solute transport in double‐porosity (DP) media under unsaturated water flow conditions is presented. The macroscopic model was developed by applying the asymptotic homogenization method. It is based on theoretical and empirical considerations dealing with the orders of magnitude of characteristic quantities involved in the process. For this purpose a physical model that mimics the behavior of DP medium was built. The resulting two‐equation model relies on a coupling exchange term between micro‐ and macro‐porosity subdomains associated with local non‐equilibrium solute concentrations. The model was numerically implemented (Comsol Multiphysics^®) to simulate the macroscopic one‐dimensional physical process taking place into the porous medium of 3D periodic microstructure. A series of dispersion experiments of NaCl solution under unsaturated steady‐state flow conditions were performed. The experimental results were used first to calibrate the dispersion coefficient of the model, and second to validate it through two other independent experiments. The excellent agreement between the numerical simulations and the measurements of the time evolution of the non‐symmetrical breakthrough curves provides a proof of predictive capacity of the developed model. Copyright © 2010 John Wiley & Sons, Ltd.     

焉耆盆地三工河组储层流体包裹体形成期次分析

焉耆盆地三工河组流体包裹体具有丰度低、个体小的特征,并以液态烃相包裹体为主,主要分布在石英颗粒的溶孔或溶缝当中。结合盆地成岩作用和有机质演化历史分析,认为它们形成于侏罗纪晚期的以压溶和溶蚀作用为特征的晚成岩作用阶段。包裹体均一温度呈双峰型分布,具有 10 1~ 110℃和 12 1~ 130℃两个区间,结合焉耆盆地的埋藏史和盆地的热史,这两个温度区间分别对应于晚侏罗世和侏罗纪末期。包裹体组份特征分析也证实该地区存在两期包裹体,并且包裹体组分主要是在烃源岩低成熟阶段形成的。可以认为,焉耆盆地三工河组储层的流体包裹体主要是在晚侏罗世烃源岩的低成熟阶段和侏罗纪末期烃源岩的成熟阶段形成。     

Equivalent Permeability and Simulation of Two-Phase Flow in Heterogeneous Porous Media

The problem of calculating equivalent grid block permeability tensors for heterogeneous porous media is addressed. The homogenization method used involves solving Darcy's equation subject to linear boundary conditions with flux conservation in subregions of the reservoir and can be readily applied to unstructured grids. The resulting equivalent permeability tensor is stable as defined relative to G-convergence. It is proposed to use both conforming and mixed finite elements to solve the local problems and compute approximations from above and below of the equivalent permeability, respectively. Comparisons with results obtained using periodic, pressure and no-flux boundary conditions and the renormalization method are presented. A series of numerical examples demonstrates the effectiveness of the methodology for two-phase flow in heterogeneous reservoirs.     

极点对称模态分解下西安高温天气的趋势特征

基于1960-2016年西安均一化气象资料,采用极点对称模态分解法,对西安市的高温天气变化特征进行分析,探讨赤道东太平洋海温异常（El Ni?o）、西太平洋副热带高压变化（WPSH）,与西安极端高温变化的关系。结果表明：① 采用非均一化数据,会低估西安暖夜、夏季、热夜、热浪日数变化趋势,高估冬季供暖能耗下降幅度、夏季制冷能耗上升幅度,对暖昼、高温日数影响相对较小。② 在年代变化上,暖昼、热浪、高温日数和制冷度日等四个指标,反映西安白天高温变化特征,呈现一致的四阶段“下降—上升—下降—上升”的变化过程;表征夜间高温变化的暖夜和热夜日数,以1993年为节点,呈现两阶段“阶梯状”的上升趋势。③ 在影响因素上,赤道太平洋中西部海温异常与西安高温关系更为密切。当Ni?o 4区海温异常偏高时,西安暖昼、夏季、炎热天气制冷耗能明显增加,寒冷天气供暖能耗显著降低;同时,当WPSH强度越大,控制面积越大、西伸脊点偏西时,西安暖夜、夏季、热夜日数明显增加、寒冷天气供暖能耗明显下降。     

四川盆地威远气田碳酸盐岩中有机包裹体研究

本文通过对威远、资阳地区上震旦统碳酸盐岩储集层中有机包裹体的研究,提出有机包裹体多分布于储层孔洞缝中所充填的三期矿物中,研究区油气运移的主要通道是溶蚀孔洞和裂缝。并根据不同期次充填矿物中有机包裹体特征、均一温度及单个有机包裹体成分,追索了研究区油气热演化程度、油气运移期次、油气运移的深度和温度。研究结果表明,研究区存在三次主要的油气运移和聚集,其各自演化的程度及油气运移的深度和温度皆不同。     

Yield design of dry‐stone masonry retaining structures—Comparisons with analytical,numerical, and experimental data

Over the past few years, there has been a steady increase in the interest in dry‐stone walling not only to preserve existing constructions but also to build new ones. Yet, dry masonry's expansion is slowed down by the lack of scientific knowledge to assess its reliability. This study aims at contributing to the construction of this scientific frame using a simplified model based on yield design and homogenization, which can be directly exploited for engineering purposes. A new analytical expression of the ultimate load is thus established. Then, the validity of the method is assessed by comparisons with limit equilibrium analysis, distinct element method, and field trials. Finally, possible improvements of the model are discussed. Copyright © 2008 John Wiley & Sons, Ltd.