On the interaction of water waves and seabed by the porous medium model

The interaction of water waves and seabed is studied by using Yamamoto's model, which takes into account the deformation of soil skeletal frame, compressibility of pore fluid flow as well as the Coulumb friction. When analyzing the propagation of three kinds of stress waves in seabed, a simplified dispersion relation and a specific damping formula are derived. The problem of seabed stability is further treated analytically based on the Mohr-Coulomb theory. The theory is finally applied to the coastal problems in the Lian-Yun Harbour and compared with observations and measurements in soil-wave tank with satisfactory results.

Influence Of Rayleigh Effect Combined With Marangoni Effect On The Onset Of Convection In A Liquid Layer Overlying A Porous Layer

The coupling mechanism of Rayleigh effect and Marangoni effect in a liquid-porous system is investigated using a linear stability analysis. The eigenvalue problem is solved by means of a Chebyshev tau method. Results indicate that there are three coupling modes between the Rayleigh effect and the Marangoni effect for different depth ratios. (C) 2008 Elsevier Ltd. All rights reserved.

Thermocapillary Convection In An Inhomogeneous Porous Layer

A new model consisting of an inhomogeneous porous medium saturated by incompressible fluid is investigated. We focus on the effects of inhomogeneity for the streamline patterns and instabilities of the system. Influences of the 'mean porosity' and gradient of distributions of porosity are also emphasized. The results cannot be obtained by studying the media with constant porosity as carried out by other researchers, and have not been discussed before.

A geometry model for tortuosity of flow path in porous media

A simple geometry model for tortuosity of flow path in porous media is proposed based on the assumption that some particles in a porous medium are unrestrictedly overlapped and the others are not. The proposed model is expressed as a function of porosity and there is no empirical constant in this model. The model predictions are compared with those from available correlations obtained numerically and experimentally, both of which are in agreement with each other. The present model can also give the tortuosity with a good approximation near the percolation threshold. The validity of the present tortuosity model is thus verified.

Instabilities of a liquid film flowing down an inclined porous plane

The problem of a film flowing down an inclined porous layer is considered. The fully developed basic flow is driven by gravitation. A careful linear instability analysis is carried out. We use Darcy's law to describe the porous layer and solve the coupling equations of the fluid and the porous medium rather than the decoupled equations of the one-sided model used in previous works. The eigenvalue problem is solved by means of a Chebyshev collocation method. We compare the instability of the two-sided model with the results of the one-sided model. The result reveals a porous mode instability which is completely neglected in previous works. For a falling film on an inclined porous plane there are three instability modes, i.e., the surface mode, the shear mode, and the porous mode. We also study the influences of the depth ratio d, the Darcy number delta, and the Beavers-Joseph coefficient alpha(BJ) on the instability of the system.

Instabilities and transient behaviors of a liquid film flowing down a porous inclined plane

The nonmodal linear stability of a falling film over a porous inclined plane has been investigated. The base flow is driven by gravity. We use Darcy's law to describe the flow in the porous medium. A simplified one-sided model is used to describe the fluid flow. In this model, the influence of the porous layer on the flow in the film can be identified by a parameter beta. The instabilities of a falling film have traditionally been investigated by linearizing the governing equations and testing for unstable eigenvalues of the linearized problem. However, the results of eigenvalue analysis agree poorly in many cases with experiments, especially for shear flows. In the present paper, we have studied the linear stability of three-dimensional disturbances using the nonmodal stability theory. Particular attentions are paid to the transient behavior rather than the long time behavior of eigenmodes predicted by traditional normal mode analysis. The transient behaviors of the response to external excitations and the response to initial conditions are studied by examining the pseudospectral structures and the energy growth function G(t) Before we study the nonmodal stability of the system, we extend the results of long-wave analysis in previous works by examining the linear stabilities for streamwise and spanwise disturbances. Results show that the critical conditions of both the surface mode and the shear mode instabilities are dependent on beta for streamwise disturbances. However, the spanwise disturbances have no unstable eigenvalue. 2010 American Institute of Physics. [doi:10.1063/1.3455503]

可动凝胶渗流规律研究现状与发展方向

系统分析了可动凝胶与聚合物体系驱油机理和适用条件的区别以及在渗流规律方面的研究现状，总结出了聚合物凝胶一般分类及其特性。提出了研究可动凝胶渗流规律需要分段试验研究流变关系来确定视黏度的变化规律，需要确定视黏度下的相渗规律变化，需要对可动凝胶的整个驱替过程统一考虑，具体研究工作中应该进行分段研究的观点。该研究对指导可动凝胶渗流规律研究和可动凝胶在提高采收率中的应用具有一定的借鉴意义。

Simulation of Natural Gas Production in Hydrate Reservoirs

This paper simulates a one-dimensional physical model of natural gas production from hydrate dissociation in a reservoir by depressurization. According to the principles of solid hydrate decomposition in stratum and flow of natural gas in porous medium, the pressure governing equations for both gas zone and hydrate zone are set up based on the physical production model. Using the approximation reported by N. N. Verigin et al. (1980), the nonlinear governing equations are simplified and the self-similar solutions are obtained. Through calculation, for different reservoir parameters, the distribution characters of pressure are analyzed. The decline trend of natural gas production rate with time is also studied. The simulation results show that production of natural gas from a hydrate reservoir is very sensitive to several reservoir parameters, such as wellbore pressure and stratum porosity and permeability.

Influence of A-type Zeolite on Methane Hydrate Formation

The porous medium has an important effect on hydrate formation. In this paper, the formation process and the gas storage capacity of the methane hydrate were investigated with A-type zeolite and Sodium Dodecyl Sulfate (SDS) existing in the system. The results show that A-type zeolite can influence methane hydrate formation. At the temperature of 273.5 K and pressure of 8.3 MPa, the distilled water with A-type zeolite can form methane hydrate with gaseous methane in 12 hours. The formation process of the system with A-type zeolite was quite steady and the amount of A-type zeolite can influence the gas storage capacity significantly. The adding of A-type zeolite with 0.067 g.(g water)(-1) into 2 x 10(-3) g.g(-1) SDS-water solution can increase the gas storage capacity, and the maximum increase rate was 31%. Simultaneously the promotion effect on hydrate formation of 3A-type zeolite is much more obvious than that of 5A-type zeolite when the water adding amounts are 0.033 g.g(-1) and 0.067 g.g(-1) at the experimental conditions.

Enhancements of the simulation method on the edge effect in resin transfer molding processes

In resin transfer molding processes, small clearances exist between the fiber preform and the mold edges, which result in a preferential resin flow in the edge channel and then disrupt the flow patterns during the mold filling stage. A mathematical model including the effect of cavity thickness on resin flow was developed for flow behavior involving the interface between an edge channel and a porous medium. According to the mathematical analysis of momentum equations in a fully developed rectangular duct and formulations of the equivalent edge permeability, comparing with three-dimensional Navier-Stokes equations, the governing equations were modified in the edge channel. The volume of fluid (VOF) method was applied to track the flow front. A simple case is numerically simulated using the modified governing equations. The effects of edge channel width and cavity thickness on flow front and inlet pressure are analyzed, and the evolution characteristics of simulated results are in agreement with the experimental results. (c) 2007 Elsevier B.V. All rights reserved

西峰油田特低渗透油藏渗流机理及开发对策研究

Micro-pore-throat, micro-fracture and low permeability are the most obvious characters of Xifeng ultra-low permeability reservoir, and threshold pressure gradient and medium deformation during the period of oilfield developing results non-linear seepage feature of the formation liquid flowing in the porous medium underground. It is impossible to solve some problems in the ultra-low permeability reservoir development by current Darcy filtration theory and development techniques. In the view of the characters of ultra-low permeability and powerful-diagenesis and fracture up-growth, the paper quantitatively characterizes of through-going scope for reservoir parameters together with some materials such as similarity field outcrop, rock core, drilling, well logging and production dynamic, which provides geological base for further development adjustment. Based on the displacement experiment of different kinds of seepage fluid and oil-water two phases, this paper proves the relationship between threshold pressure gradient and formation permeability in experiment and theory, which is power function and its index is about -1. The variation rule and the mechanism of oil-water two phases threshold pressure gradient are studied. At the same time, based on the experiment of medium deformation, the variation rule of formation physical property parameters and the deformation mechanism are researched, and the influential factors on the medium deformation are analyzed systematically. With elastic unsteady filtration theory, nonlinear mathematical models of the steady and unsteady flow of single phase as well as horizontal well flow and oil-water two phases flow are deduced with the influence of nonlinear factors including threshold pressure gradient and media deformation. The influences of nonlinear factors upon well deliverability and reservoir pressure distribution as well as the saturation variation pattern of oil-water front are analyzed. By means of the researches such as reasonable well pattern, reasonable well array ration, artificial fracture length optimization advisable water flood timing and feasibility of advanced water flooding, it is necessary to find out effective techniques in order to improve development result of this kind of reservoir. This research result develops and improves on low-velocity nonlinear seepage theory, and offers ways to study similar kind of reservoir; it is meaningful to the development of the ultra-low permeability oil and gas reservoir.

束鹿凹陷泥灰岩储层综合评价与加砂压裂技术研究与应用

Luo Ning ( Mineralogy, Petrology, Deposit Mineralogy) Directed by Fu Liyun With the increase of the level of exploration and development, North China field, as one of the maturing fields in the east, has gradually turned their prospecting targets to frontiers such as deep zones, lithologic hydrocarbon reservoirs, low permeable layers, special lithostromes, etc, which propose new challenges to mating technique of exploration engineering. In it, the special lithostrome of clay carbonate in Shu-Lu cave in Middle Flank exploration area locates in Es_3 generating rock. The area distribution is large, formation thickness is over 100 meters, the oil accumulation condition is excellent, prognostic reserves is over 80,000,000 tons, but how to effectively stimulate the special low permeable and fractured reservoir has become the bottle neck problem of stimulation and stable yields. In this thesis, through comprehensive evaluation and analysis of lithology, lithomechanics, hydrocarbon reservoir characteristics, the characteristics of fluid flow through porous medium and the stimulation measures in the past, we acquire new cognition of clay carbonate reservoirs, in addition, the research and application of first hydraulic fracturing has gained positive effect and formed commensurable comprehensive reservoir evaluation technique and mating engineering technique of hydraulic fracturing. The main cognitions and achievements are as follows: 1.Study of geological information such as lithololy analysis and nuclear magnetic logging, etc, indicates that clay carbonate formation of Shu-Lu cave is anisotropic, low permeable with high shale content, whose accumulation space gives priority to microcracks. 2.The analysis of lithomechanics of clay carbonate indicates that the hardness is moderate, Young’s modulus is between that of sandstone and limestone, clay carbonate presents plastic property and its breakdown pressure is high because of the deep buried depth. 3.The analysis of the drillstem test curves indicates that the flow and build-up pressure curve of clay carbonate of Shu-Lu cave mainly has three types: formation contamination block-up type, low permeable type, formation energy accumulation slowness type; the reservoir characteristics presents double porosity media, radial compounding, uniform flow vertical fracture, isotropy, moniliform reservoir type. The target well Jingu 3 belongs to moniliform reservoir type. 4.Through recognition and re-evaluation of the treatment effect and technologic limitations of acidizing, acid fracturing and gelled acidizing in the past, based on the sufficient survey and study of hydraulic fracturing home and abroad, combined with comprehensive formation study of target well, we launched the study of the optimization of hydraulic fracturing technique, forming the principal clue and commensurable mating technology aimed at clay carbonate formation, whose targets are preventing leak off, preventing sand bridge, preventing embedment, controlling fracture height, forming long fracture. 5. Recognition of stimulation effect evaluation.

二氧化碳在孔隙咸水层中多相流动数值模拟研究

There has been a growing concern about the use of fossil fuels and its adverse effects on the atmospheric greenhouse and ecological environment. A reduction in the release rate of CO2 into the atmosphere poses a major challenge to the land ecology of China. The most promising way of achieving CO2 reduction is to dispose of CO2 in deep saline aquifers. Deep aquifers have a large potential for CO2 sequestration in geological medium in terms of volume and duration. Through the numerical simulation of multiphase flow in a porous media, the transformation and motion of CO2 in saline aquifers has been implemented under various temperature and hydrostatic pressure conditions, which plays an important role to the assessment of the reliability and safety of CO2 geological storage. As expected, the calculated results can provide meaningful and scientific information for management purposes. The key problem to the numerical simulation of multiphase flow in a porous media is to accurately capture the mass interface and to deal with the geological heterogeneity. In this study, the updated CE/SE (Space and time conservation element and solution element) method has been proposed, and the Hybrid Particle Level Set method (HPLS) has extended for multiphase flows in porous medium, which can accurately trace the transformation of the mass interface. The benchmark problems have been applied to evaluate and validate the proposed method. In this study, the reliability of CO2 storage in saline aquifers in Daqingzi oil field in Sunlong basin has been discussed. The simulation code developed in this study takes into account the state for CO2 covering the triple point temperature and pressure to the supercritical region. The geological heterogeneity has been implemented, using the well known geostatistical model (GSLIB) on the base of the hard data. The 2D and 3D model have been set up to simulate the CO2 multiphase flow in the porous saline aquifer, applying the CE/SE method and the HPLS method .The main contents and results are summarized as followings. (1) The 2D CE/SE method with first and second –order accuracy has been extended to simulate the multiphase flow in porous medium, which takes into account the contribution of source and sink in the momentum equation. The 3D CE/SE method with the first accuracy has been deduced. The accuracy and efficiency of the proposed CE/SE method have been investigated, using the benchmark problems. (2) The hybrid particle level set method has been made appropriate and extended for capturing the mass interface of multiphase flows in porous media, and the numerical method for level set function calculated has been formulated. (3) The closed equations for multiphase flow in porous medium has been developed, adept to both the Darcy flow and non-Darcy flow, getting over the limitation of Reynolds number to the calculation. It is found that Darcy number has a decisive influence on pressure as well as velocity given the Darcy number. (4) The new Euler scheme for numerical simulations of multiphase flows in porous medium has been proposed, which is efficient and can accurately capture the mass interface. The artificial compressibility method has been used to couple the velocities and pressure. It is found that the Darcy number has determinant effects on the numerical convergence and stability. In terms of the different Darcy numbers, the coefficient of artificial compressibility and the time step have been obtained. (5) The time scale of the critical instability for critical CO2 in the saline aquifer has been found, which is comparable with that of completely CO2 dissolved saline aquifer. (6) The concept model for CO2 multiphase flows in the saline aquifer has been configured, based on the temperature, pressure, porosity as well as permeability of the field site .Numerical simulation of CO2 hydrodynamic trapping in saline aquifers has been performed, applying the proposed CE/SE method. The state for CO2 has been employed to take into account realistic reservoir conditions for CO2 geological sequestration. The geological heterogeneity has been sufficiently treated , using the geostatistical model. (7) It is found that the Rayleigh-Taylor instability phenomenon, which is associated with the penetration of saline fluid into CO2 fluid in the direction of gravity, has been observed in CO2 multiphase flows in the saline aquifer. Development of a mushroom-type spike is a strong indication of the formation of Kelvin-Helmholtz instability due to the developed short wavelength perturbations present along the interface and parallel to the bulk flow. Additional key findings: the geological heterogeneity can distort the flow convection. The ascending of CO2 can induce the persistent flow cycling effects. The results show that boundary conditions of the field site have determinant effects on the transformation and motion of CO2 in saline aquifers. It is confirmed that the proposed method and numerical model has the reliability to simulate the process of the hydrodynamic trapping, which is the controlling mechanism for the initial period of CO2 storage at time scale of 100 years.

胶东地区三类金矿成矿系统地质地球化学及动力学

The East Shandong gold province is located on the southeastern margin of the North China Craton and features uplift in the north and depression in the south. The uplift area is made up of the Archaean Jiaodong Group, the Proterozoic Jingshan Group and Yanshannian granites. Most gold deposits in the uplift area are spatially associated with the Yanshannian granites. Two types of gold mineralization occur in the region: the quartz-vein type hosted in the Linglong granite suite, and the shear zone type hosted by either the Linglong granite or Guojialing granitoid suites. The mineralization ages are 113～126 Ma. The southern part of East Shandong contains the Mesozoic Jiaolai basin, which formed during regional extension. The basin is bounded by the Wulian-Rongcheng fault in the southeast and the Tanlu fault in the west. The Pengjiakuang, Fayunkuang and Dazhuangzi gold deposit occurs on the northeastern margin of the basin. The mineralization ages of these deposits are 110～128 Ma. This paper focuses on a low-angle detachment fault developed between the Proterozoic Jingshan Group metamorphic complex and the northeastern margin of the basin. Our field work shows that the distribution of the Pengjiakuang gold deposit was controlled by the detachment fault. Moreover, the Fayunkuang, Guocheng and Liaoshang gold deposits also occurr in the periphery of the basin, and their features are similar to Pengjiakuang gold deposit. The study of geological geochemistry of the gold deposits has shown: ①three-type gold deposit was situated in the Jiaodong area, including altered rock type (Jiaojia type), quartz vein type (Linglong type) and breccia type (Pengjiakuang type); the ore-forming materials and fluid for Pengjiakuang type gold deposit shows multiple source; ②the ore materials of Jiaojia and Linglong type deposits are mainly from deep source. The author has studied geological-geochemical dynamics of three types deposits in Jiaodong area. The study of tectonic dynamics shows that ore-forming structure differential stress values of Pengjiakuang gold deposit is 100 * 10~6～130 * 10~6 Pa, and that of Jiaojia gold deposit is 100 * 10~5～194 * 10~6 Pa. Dynamics of hydrothermal ore-forming fluid has also been studied in this paper. Author applies Bernoulli equation to dynamic model of hydrothermal fluid motion in brittle fracture and cracks (quartz vein type gold mineralization), and applies Darcy law to dynamic model of hydro thermal fluid motion in porous medium (altered rock type gold mineralization). Author does daring try in order to study quantitativly transport mechanism of hydrothermal ore-forming fluid in this paper. The study of fluid inclusions and crystal dynamics shows that reaction system of hydrothermal ore-forming includes three types, as follows: ore-forming reaction, controlling reaction and buffer controlling reaction. They depend on each other, controlling each other, which form a organic system. Further research shown that formation of ore shoots was controlled by coincidence processes of tectonic dynamic condition and thermodynamic evolution. This paper has summaried reginoal metallogenic laws and seted up metallogenic(dynamics) models for Jiaodong gold ore belt.