共查询到20条相似文献，搜索用时 109 毫秒
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Zonal distribution of seepage hydrocarbon-induced altereb carbonates over oil/gas reservoirs is a common phenomenon observed in the field.The authors considered that the continuous production of CO2 within the “alteration chimney ”gives rise to a significant difference in physical and chemical properties between its interior and the surrounding country rocks.And it is this difference that has promoted the erosion and precipitation of carbonates,thus leading to the zonal distribution of seepage hydrocarbon-induced altered carbonates over oil/gas reservoirs.This may be a reasonable interpretation of the phenomenon described above. 相似文献
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Astronomy Reports - Improvement of the prediction accuracy of the Earth’s rotation parameters (ERP) is one of the main problems of applied astrometry. In order to solve this problem, various... 相似文献
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This paper deals with a simulated test of biogenic mineralization made with a blue-green alga species,Spirulina platensix. The data in the experiment were recorded by a computerized surveying system. The influ-ence of algae on the accumulation of phosphorus by changing their microenvironment to promote the forma-tion and deposition of phosphate was studied. The results show that the pH value of cultural liquor rose up to 10 and the redox potential (Eh) may dropby 100-200 mV during the algal logarithmic growth stage, and the cultrual liquor was changed into a mediumwith a weakly reducing condition. At the end of the logarithmic growth stage white deposits of Na_2Ca(CO_3)_2·5H_2O and Ca_2Mg (PO_4)_2·2H_2O were formed on the floor of cultural containers. The test presented a wduableevidence for the theory of biogenic mineralization. 相似文献
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Wang Ende Shenyang Institute of Gold Technology Shenyang Liaoningand Guan Guangyue Northeast U niversity of Technology Shenyang Liaoniny 《《地质学报》英文版》1994,68(1):31-42
The bacteria used in the experiment are Thiobacillus Ferrooxidans separated from acidic mine water in sulphide deposits. The chemoautotrophic bacteria can act directly on sulphides and accelerate the oxidation of sulphides. The experiment shows that the bacteria, as an important microbial factor of gold's supergenous enrichment within the oxidized zones of sulphide deposits, are helpful to dissolve gold and silver in ferric sulphate. In the bacterial oxidation process, the precipitation of goethite is concerned both with the lower activity of ferric ions and with the existence of carbonates in solution. Meanwhile, the acid-resisting and oxidizing ability of the bacteria will certainly lead up to a microbial way of treating the acidic mine water. 相似文献
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The coupled discrete element method and lattice Boltzmann method (DEMLBM) has increasingly drawn attention of researchers in geomechanics due to its mesoscopic nature since 2000. Immersed boundary method (IBM) and immersed moving boundary (IMB) are two popular schemes for coupling fluid particle in DEMLBM. This work aims at coupling DEM and LBM using the latest IBM algorithm and investigating its accuracy, computational efficiency, and applicability. Two benchmark tests, interstitial fluid flow in an ideal packing and single particle sedimentation in viscous fluid, are carried out to demonstrate the accuracy of IBM through semi-empirical Ergun equation, finite element method (FEM), and IMB. Then, simulations of particle migration with relatively large velocity in Poiseuille flow are utilized to address limitations of IBM in DEMLBM modeling. In addition, advantages and deficiencies of IBM are discussed and compared with IMB. It is found that the accuracy of IBM can be only guaranteed when sufficient boundary points are used and it is not suitable for geomechanical problems involving large fluid or particle velocity. 相似文献
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非常规油气资源的孔隙结构及其连通性非常复杂，其孔隙尺度从毫米到纳米跨越多个量级.多孔介质中气体的输运过程不仅依赖于介质的多尺度微观结构特征，还依赖于气体的相关属性.气体在多尺度多孔介质中的输运过程包括无滑流、滑脱流和过渡流，涉及分子扩散和努森扩散等多种机制，因此很难用唯一的连续介质理论来描述气体的输运特征.大量的数据表明真实多孔介质中的内部孔隙具有分形标度特征，因此采用分形几何表征多尺度多孔介质的孔隙结构，引入孔隙分形维数和迂曲度分形维数定量表征多孔介质的微结构和弯曲流道，建立多尺度多孔介质气体输运过程的细观模型；推导了多尺度多孔介质中气体的有效渗透率和有效扩散系数，并讨论了多尺度多孔介质微结构参数和气体属性对于气体等效输运特性的定量影响.该研究不仅可以丰富渗流理论，且有利于深入理解非常规油气藏的产出机制. 相似文献
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用格子波耳兹曼方法模拟双重孔隙介质中的流体迁移 总被引：3，自引：0，他引：3
作者在本文中介绍了基于格子波耳兹曼模型的双重孔隙介质中流体运移的数值模拟计算方法。我们从格子波耳兹曼碰撞模型出发，利用格子波耳兹曼方程、Chapman-Enskog展开，以及多尺度技术，得到了描述双重孔隙介质中流体迁移的二维扩散方程。利用格子气自动机方法计算该扩散方程，实现了对双重孔隙介质中流体运移过程的数值模拟仿真。数值实验表明，我们所使用的方法正确、有效。 相似文献
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Hongyang Cheng Stefan Luding Nicolás Rivas Jens Harting Vanessa Magnanimo 《国际地质力学数值与分析法杂志》2019,43(5):1115-1139
Biot theory predicts wave velocities in a saturated granular medium using the pore geometry, viscosity, densities, and elastic moduli of the solid skeleton and pore fluid, neglecting the interaction between constituent particles and local flow, which becomes essential as the wavelength decreases. Here, a hydro-micromechanical model, for direct numerical simulations of wave propagation in saturated granular media, is implemented by two-way coupling the lattice Boltzmann method (LBM) and the discrete element method (DEM), which resolve the pore-scale hydrodynamics and intergranular behavior, respectively. The coupling scheme is benchmarked with the terminal velocity of a single sphere settling in a fluid. In order to mimic a small amplitude pressure wave entering a saturated granular medium, an oscillating pressure boundary on the fluid is implemented and benchmarked with the one-dimensional wave equation. The effects of input waveforms and frequencies on the dispersion relations in 3D saturated poroelastic media are investigated with granular face-centered-cubic crystals. Finally, the pressure and shear wave velocities predicted by the numerical model at various effective confining pressures are found to be in excellent agreement with Biot analytical solutions, including his prediction for slow compressional waves. 相似文献
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Pore structures of porous media and properties of fluid flow are key factors for the study of non-Darcy groundwater flow. However, it is difficult to directly observe pore structures and flow properties, resulting in a “black box” problem of porous media. This problem has hindered the in-depth study of the groundwater flow mechanism at the pore scale. In recent years, 3D rapid prototyping technology has seen tremendous development. 3D printing provides digital models and printing models of porous media with clear internal structure. Thus, Lattice Boltzmann Method can be used to simulate the flow processes at the pore scale based on real pore structures. In this study, 3D printing cores and Lattice Boltzmann Method were coupled to conduct both laboratory and numerical experiments in spherical porous media with different sphere diameters and periodic arrays. The LBM simulation results show a good agreement with laboratory experimental results. With the advantages of LBM and 3D printing, this approach provides a visualization of the complex pore structure and fluid flow in pores, which is a promising method for studies of non-Darcy groundwater flow at the pore scale. 相似文献
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A preliminary problem to solve in the set-up of a mathematical model simulating a geophysical process is the choice of a suitable discrete scheme to approximate the governing differential equations. This paper presents a simple technique to test finite difference schemes used in the modeling of geophysical processes occurring in a geological structure. This technique consists in generating analytical solutions similar to the ones characterizing a geophysical process, given general information on some relevant parameters. Useful information for the choice of the discrete scheme to employ in the mathematical model simulating the original geophysical process can be obtained from the comparison between the analytical solution and the approximated numerical solutions generated by means of different discrete schemes. Two classes of numerical examples approximating the differential equation that governs the steady state earth's heat flow have been treated using three different finite differences schemes. The first class of examples deals with media whose phenomenological parameters vary as continuous space functions; the second class, instead, deals with media whose phenomenological parameters vary as discontinuous space functions. The finite difference schemes that have been utilized are: Centered Finite Difference Scheme (CDS), Arithmetic Mean Scheme (AMS), and Harmonic Mean Scheme (HMS).The numerical simulations showed that: the CDS may yield physically inconsistent solutions if the lattice internodal distance is too large, but in case of phenomenological parameters varying as a continuous function, this pitfall can be avoided increasing the lattice node refinement. In case of phenomenological parameters varying as a discontinuous function, instead, the CDS may yield physically inconsistent solutions for any lattice-node refinement. The HMS produced good results for both classes of examples showing to be a scheme suitable to model situations like these. 相似文献
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Multiscale mixed/mimetic methods on corner-point grids 总被引：1，自引：0，他引：1
Multiscale simulation is a promising approach to facilitate direct simulation of large and complex grid models for highly
heterogeneous petroleum reservoirs. Unlike traditional simulation, approaches based on upscaling/downscaling, multiscale methods
seek to solve the full flow problem by incorporating subscale heterogeneities into local discrete approximation spaces. We
consider a multiscale formulation based on a hierarchical grid approach, where basis functions with subgrid resolution are
computed numerically to correctly and accurately account for subscale variations from an underlying (fine-scale) geomodel
when solving the global flow equations on a coarse grid. By using multiscale basis functions to discretise the global flow
equations on a (moderately sized) coarse grid, one can retain the efficiency of an upscaling method and, at the same time,
produce detailed and conservative velocity fields on the underlying fine grid. For pressure equations, the multiscale mixed
finite-element method (MsMFEM) has been shown to be a particularly versatile approach. In this paper, we extend the method
to corner-point grids, which is the industry standard for modelling complex reservoir geology. To implement MsMFEM, one needs
a discretisation method for solving local flow problems on the underlying fine grids. In principle, any stable and conservative
method can be used. Here, we use a mimetic discretisation, which is a generalisation of mixed finite elements that gives a
discrete inner product, allows for polyhedral elements, and can (easily) be extended to curved grid faces. The coarse grid
can, in principle, be any partition of the subgrid, where each coarse block is a connected collection of subgrid cells. However,
we argue that, when generating coarse grids, one should follow certain simple guidelines to achieve improved accuracy. We
discuss partitioning in both index space and physical space and suggest simple processing techniques. The versatility and
accuracy of the new multiscale mixed methodology is demonstrated on two corner-point models: a small Y-shaped sector model
and a complex model of a layered sedimentary bed. A variety of coarse grids, both violating and obeying the above mentioned
guidelines, are employed. The MsMFEM solutions are compared with a reference solution obtained by direct simulation on the
subgrid. 相似文献
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This paper describes the application of a three-dimensional lattice Boltzmann method (LBM) to Newtonian and non-Newtonian (Bingham fluid in this work) flows with free surfaces. A mass tracking algorithm was incorporated to capture the free surface, whereas Papanastasiou’s modified model was used for Bingham fluids. The lattice Boltzmann method was first validated using two benchmarks: Newtonian flow through a square cross-section tube and Bingham flow through a circular cross-section tube. Afterward, the dam-break problem for the Newtonian fluid and the slump test for Bingham fluid were simulated to validate the free-surface-capturing algorithm. The numerical results were in good agreement with analytical results, as well as other simulations, thereby proving the validity and correctness of the current method. The proposed method is a promising substitute for time-consuming and costly physical experiments to solve problems encountered in geotechnical and geological engineering, such as the surge and debris flow induced by a landslide or earthquake. 相似文献
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Laboratory validation of lattice Boltzmann method for modeling pore-scale flow in granular materials
Characteristics of fluid flow through various engineering structures, such as granular filters and asphalt pavements, influence their design life. Numerical simulation of fluid flow is useful for evaluating the hydraulic characteristics of these materials. Among various techniques, the lattice Boltzmann (LB) method is widely accepted due to the ease of implementing boundary conditions and the numerical stability in a wide variety of flow conditions. It has proven to be extremely efficient in the simulation of fluid flow through the complex geometries of granular materials. In this study, two-dimensional and three-dimensional LB models were developed to represent pore-scale monophasic Newtonian incompressible fluid flow in granular materials. Three-dimensional geometries of compacted aggregates and asphalt specimens were generated from X-ray Computed Tomography technique and used as input for the LB model. The accuracy of the models was verified by comparing the results with analytical solutions of simple geometries and hydraulic conductivity measurements on the compacted aggregates and hot mix asphalt specimens. The results of LB simulations were in excellent agreement with those obtained from analytical calculations and laboratory measurements. 相似文献