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1.
以岩石实验中矿物的几何形态及空间分布为建模依据,以实验条件及单矿物电导率的测量结果为约束条件,用有限元数值方法模拟了不同微观结构的斜长石、辉石混合物在施加电压后电势及电流的分布情况,并计算了混合模型在不同温度条件下的电导率.研究结果显示,数值模型网格数及矿物颗粒数的选取对电导率计算结果的精度有较大影响,在体导电情况下,模型电导率因矿物比例含量和排列结构而异.当斜长石及辉石随机分布时,随着辉石含量的增加,混合模型电导率在不同温度下均有所增加,且温度越高,增加幅度越大,电导率的有限元模拟计算结果接近于有效介质渗透理论模型,且位于并、串联模型之间以及HS模型的上、下边界范围内;在斜长石及辉石含量一定的情况下,各矿物的排列分布对电导率计算结果也有一定的影响,当矿物颗粒大小接近且分布均匀时,模型中电势沿电流传导方向变化较为均匀,模拟计算得出的电导率相对较高,当矿物颗粒大小差别较大及分布不均匀时,电势分布受到一定的扰动,电导率计算结果也较低.将混合模型电导率有限元计算结果与辉长岩、辉绿岩及玄武岩实验测量结果进行比较,显示这3种岩石样品电导率与温度变化关系的斜率均与混合模型计算结果的斜率相接近,表明这些岩石在所选温度段导电机制与斜长石、辉石混合模型相似,用斜长石、辉石混合模型的电导率研究玄武岩、辉长岩及辉绿岩的导电性具有适用性.将混合模型有限元计算结果与玄武岩、辉长岩、辉绿岩覆盖区地壳大地电磁实测结果对比,发现大地电磁电导率结果位于混合模型计算结果范围内,用斜长石、辉石混合模型模拟玄武岩、辉长岩等岩石地壳具有一定的可行性. 相似文献
2.
电导率是表征岩石电学性质的重要物理参数,在地质资源勘查和测井解释等领域发挥着巨大作用.快速、准确地确定岩石电导率具有重要的理论和实践意义.作为近年来发展的一种岩石物理数值模拟工具,数字岩心技术在定量计算电导率等物性参数方面应用广泛.三维微观结构的准确获取是数字岩心技术计算岩石电导率的关键,但传统获取岩石三维微观结构的方法较为复杂费时.为了方便快速地通过数字岩心技术计算岩石的电导率,本文研究了岩石二维与三维数字岩心的电导率联系.我们基于微米级X射线CT扫描得到的三个砂岩样品的微观结构信息建立了三维数字岩心,并通过有限元法计算的三维数字岩心电导率与实验数据的对比验证数值计算方法的有效性.随后我们数字地扩展了岩石的孔隙,产生了较大孔隙度的三维数字岩心样本,在此基础上,计算了三维数字岩心和相应二维数字岩心的电导率,并通过Archie公式分别拟合了电导率与孔隙度之间的关系,得到了相应的胶结系数.结果表明,三维数字岩心的胶结系数小于二维数字岩心的胶结系数,且二者的比值与岩石实测孔隙度呈线性负相关关系.以该联系为纽带,通过二维图像快速计算得到的电导率与孔隙度关系,确定了三维数字岩心的电导率与孔隙度关系,并进一步通过三维数字岩心的孔隙度计算其电导率.该方法计算得到的人工砂岩样品的电导率与其三维数字岩心电导率相关系数高于96%,验证了基于二维图像的数字岩心电导率计算方法的有效性.本文的研究结果为快速、准确地计算岩石电导率提供了新的思路,在油气勘探开发中有广阔的应用前景. 相似文献
3.
针对现有导电模型很难描述含黄铁矿混合泥质砂岩储层导电规律的难题,本文设计并压制了黄铁矿骨架纯岩样,以及不同分散泥质、层状泥质和黄铁矿含量的石英骨架人造岩样,测量了岩样岩电及配套实验数据,从实验角度分析了黄铁矿含量变化对岩石导电性的影响。考虑到岩石中不同物质成分间导电特性的差异,提出将含黄铁矿混合泥质砂岩分为层状泥质、石英颗粒、黄铁矿颗粒、油气、分散粘土颗粒、微孔隙水和可动水,将电导率差分方程与通用阿尔奇方程相结合,利用电导率差分方程描述在主介质中添加分散相介质的导电规律,而利用通用阿尔奇方程描述两种导电介质组成的混合介质的导电规律,在此基础上利用并联导电理论描述分散泥质砂岩与层状泥质的导电规律,建立了一种能够有效描述含黄铁矿混合泥质砂岩导电特性的新型通用电阻率模型。理论验证表明所建立的电阻率模型满足物理约束条件,且预测的导电规律与实验规律相一致,即随着黄铁矿颗粒含量和电导率的增加,R_t和I值均减小。利用实验测量的46块人造岩样在不同含油饱和度下的岩电实验数据,验证了该模型完全能够描述黄铁矿骨架纯岩样、石英骨架混合泥质砂岩岩样,以及骨架含部分黄铁矿的混合泥质砂岩岩样的导电规律。实现了含黄铁矿混合泥质砂岩地层饱和度的准确求取,有效的提高了复杂储层测井解释评价的精度。 相似文献
4.
《地球物理学进展》2016,(4)
复杂泥质砂岩储层的饱和度评价一直是测井解释领域亟待解决的难点和热点问题,基于并联导电理论和阿尔奇公式建立的导电模型扩展性有限,在一定程度上限制了该类模型扩展描述孔隙结构更复杂的高泥高钙砂岩储层的导电规律,而有效介质对称导电理论能很好地描述复杂泥质砂岩储层导电规律,具有很好的应用前景,但仍需深入研究.首先针对纯砂岩,使用有效介质对称导电理论建立纯砂岩有效介质对称导电模型,理论分析与实验研究表明纯砂岩有效介质对称导电模型优于阿尔奇方程,不但可以描述纯砂岩阿尔奇规律,而且可以描述纯砂岩非阿尔奇规律,并且满足当孔隙度等于1时地层因素等于1,以及当含水饱和度等于1时电阻增大系数等于1的物理约束,可更好地描述纯砂岩导电规律.其次,针对分散泥质砂岩,使用有效介质对称导电理论建立泥质砂岩有效介质对称导电模型,理论分析与实验研究表明,泥质砂岩有效介质对称导电模型优于泥质电阻率模型和双电层模型,不需要采用经验拟合就能完整地描述饱含水分散泥质砂岩的电导率与地层水电导率之间曲线和直线关系,模型预测的粘土含量和粘土电导率变化对岩石导电规律的影响与理论认识相符,可更好地描述分散泥质砂岩导电规律.第三,针对两组分混合介质,使用有效介质对称导电理论、并联导电理论、串联导电理论,分别建立了有效介质对称导电方程、并联导电方程、串联导电方程,理论比较表明有效介质对称导电理论与并联导电理论和串联导电理论均不等价,即当两种组分混合介质遵循并联或串联导电规律时,混合介质的导电规律不能用有效介质对称导电理论描述.有效介质对称导电理论能够描述骨架和水以及粘土均为连续项的岩石导电规律.它通过引入渗滤指数和渗滤速率几何参数来描述各种组份的连通性、表面的粗糙度、形状、润湿性等对岩石导电性的影响,因此,有效介质对称导电理论的适用性更广,可用于描述孔隙结构更复杂的高泥高钙砂岩储层的导电规律. 相似文献
5.
《应用地球物理》2017,(1)
针对祁连山冻土区DK-4井孔含水合物岩层构建岩石物理模型,分别采用K-T方程模型方法和区分填充模式的等效介质模型方法(模式Ⅰ和模式Ⅱ)。K-T方程主要模拟地震波在两相介质中传播,基于弹性模量计算速度;而等效介质模型主要依据对水合物地层介质的两种假设:模式Ⅰ是将水合物作为孔隙填充物的一部分,模式Ⅱ是将水合物作为岩石骨架的一部分。首先根据粉砂岩层段的测井数据提取了水合物地层骨架的物性参数,包括纵波速度、横波速度、密度、体积模量和剪切模量。然后依据水合物地层各主要成分的物性参数,建立了基于K-T方程的岩石物理模型和区分填充模式的等效介质模型。将两类模型的速度曲线分别与实际地层数据进行了对比:由K-T方程建立的岩石物理模型,其理论计算的速度偏离实际值;而区分填充模式的等效介质模型,其理论计算的速度符合实际值,并且填充模式Ⅱ模型的速度曲线比填充模式Ⅰ模型更接近实际地层情况。采用区分填充模式的等效介质模型,能够更好地实现对祁连山冻土区水合物粉砂岩地层的模拟。 相似文献
6.
双频电磁波电导率层析成像反演 总被引：1，自引：0，他引：1
介绍一个新的跨井电磁波层析成像方法,该方法利用两个频率的透射电磁波的电场强度之比值重建研究区域的电导率分布图像,无需计算发射天线的初始辐射场强与辐射方向因子.详细讨论了双频电磁波电导率层析成像的方法与其适用条件,并给出了应用实例.双频电磁波电导率层析成像适用于良导介质(＞0.01 S/m)和1-100MHz工作频率情况.该方法应用于实际数据,获得了较传统吸收成像更精细的层析图. 相似文献
7.
本文采用格子玻耳兹曼方法计算混合物的整体电导率．整体电导率与各组分的电导率、体积分数和混合物结构有关．数值计算方法的有效性通过两相混合物并联或串联模型的解析解加以验证．对随机分布模型的计算发现格子玻耳兹曼方法得到的电导率落在H S理论边界内．对Al Bi合金整体电导率的数值模拟结果和实验结果非常相近．对饱和水岩石的介电常数的计算与实验结果相比误差较小．格子玻耳兹曼方法为混合物的整体电导率的计算提供了一个有效的途径. 相似文献
8.
实际地震勘探中,储层物性参数的差异是导致地震波响应特征发生变化的根本原因,而建立储层物性参数与地震响应特征之间的联系,需要跨越微观孔隙尺度、介观测井尺度以及宏观地震尺度等三个不同尺度空间.本文基于已知井的岩石物理实验数据和测井数据,利用复杂多孔隙介质理论将微观尺度孔隙岩石粗化到介观测井尺度,利用Backus平均理论将介观测井尺度的模型进一步粗化到宏观地震尺度,最终,得到地震尺度裂缝-多孔隙介质模型.其数值计算结果与测井数据和地震数据的对比表明：基于两级尺度粗化算法的裂缝多孔隙介质模型在给定参数下是有效的,且基于该模型的地震响应特征分析方法能够对储层的地震响应特征随物性参数的变化进行分析. 相似文献
9.
相对于常规砂岩,致密砂岩在岩石物理性质、力学性质等方面具有明显差异,并呈现出很强的非均质性.岩石物理模型能将储层参数与地震特性信息联系起来,因此可以作为致密砂岩储层参数与地震特性信息转换的桥梁.常规的岩石物理模型通常只考虑单一因素(例如非均匀性,单一孔隙,单一尺度等),建立的岩石物理模板并不适用于致密砂岩.本文针对高饱和气、微裂隙发育、非均质性强的致密砂岩储层,利用Voigt-Reuss-Hill模型计算混合矿物的弹性模量,采用微分等效介质(DEM)模型描述含裂隙、孔隙岩石的骨架弹性模量,基于Biot-Rayleigh波动方程构建了岩石物理弹性模板,给出了致密砂岩储层弹性参数与物性的关系.基于测井数据和实验数据对岩石物理弹性模板进行校正,并将校正后的岩石物理弹性模板结合叠前地震资料应用于川西地区储层孔隙度与裂隙含量预测.结果显示,反演裂隙含量、孔隙度与储层试气报告、测井孔隙度基本吻合,表明该模板能够较合理地应用于致密砂岩储层孔隙度及裂隙含量解释中. 相似文献
10.
从二维麦克斯韦方程组出发推导出反演介电常数和电导率等二维介质物性参数的反演公式.反演的步骤是: 建立初始猜测模型，利用电磁波时间域有限差分法模拟正演数据，用正演数据与观测数据之间的数据残差建立目标函数，通过引入一个由麦克斯韦方程计算的伴随场，将目标函数对介质参数的导数表示成显式形式，应用最优化理论得出对初始猜测模型的修改，用共轭梯度法迭代，最终得到反演结果.用合成数据反演具有粗糙地表的非导电介质的介电常数，用实验数据同时反演介电常数和电导率，并比较了麦克斯韦方程反演结果与声波方程反演结果、波动方程偏移剖面的差异. 相似文献
11.
Paul W.J. Glover Malcolm J. Hole Jaume Pous 《Earth and Planetary Science Letters》2000,180(3-4):369-383
Many types of mixing model are used widely within the earth sciences to determine the electrical properties of porous media consisting of solid and fluid phases of known conductivities, volume fractions and distributions (i.e. phase connectivities). Most models are valid for two or more conducting phases. However, of the simple models only Archie’s law includes a variable term, the Archie cementation exponent m, that describes the connectivity of the phases. Unfortunately, Archie’s law is only valid for one conducting phase distributed within a non-conducting phase, which makes it inapplicable in instances where the rock matrix has a significant conductivity such as for clay-rich rocks and in calculations involving partial melting. More complex models exist which account for multiple conducting phases and control over phase conductivity. We have adapted the conventional Archie’s law to produce a simple modified Archie’s law that can be used with two conducting phases of any conductivity and any volume fraction, while retaining the ability to model variable connectivities within those phases that result from variations in their distribution. The modified model has two exponents (m and p) that describe the connectivity of each of the two phases. The exponents are related through an equation that depends also on the volume fractions of the two phases. The modified and the conventional versions of Archie’s law have been tested on a granular analogue porous medium with a conducting matrix and a pore space saturated with a range of saline fluids with different salinities and conductivities. The new model describes the experimentally determined electrical behaviour of the system extremely well, improving greatly on the conventional Archie’s law. 相似文献
12.
Spatial scale effect on the upper soil effective parameters of a distributed hydrological model 总被引：1，自引：0，他引：1
Nonlinear dynamics and spatial variability in hydrological systems make the formulation of scaling theories difficult. Therefore, the development of knowledge related to scale effects, scaling techniques, parameterization and linkages of parameters across scales is highly relevant. The main purpose of this work is to analyse the spatial effect of the static storage capacity parameter Hu and the saturated hydraulic conductivity parameter ks from microscale (sub‐grid level) to mesoscale (grid level) and its implication to the definition of an optimum cell size. These two parameters describe the upper soil water characteristics in the infiltration process conceptualization of the TETIS hydrological model. At microscale, the spatial heterogeneity of Hu and ks was obtained generating random parameter fields through probability distribution functions and a spatial dependence model with pre‐established correlation lengths. The effective parameters at mesoscale were calculated by solving the inverse problem for each parameter field. Results indicate that the adopted inverse formulation allows transferring the nonlinearity of the system from microscale to the mesoscale via non‐stationary effective parameters. Their values at each cell and time step are in the range of zero to the mean value of the parameter at microscale. The stochastic simulations showed that the variance of the estimated effective parameters decreases when the ratio between mesoscale cell size and correlation length at microscale increases. For a ratio greater than 1, we found cell sizes having the characteristics of a representative elementary area (REA); in such case, the microscale variability pattern did not affect the system response at mesoscale. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
13.
Angus I. Best Lucy M. MacGregor Jeremy Sothcott Tim A. Minshull 《Geophysical Prospecting》2011,59(4):777-786
Improvements in the joint inversion of seismic and marine controlled source electromagnetic data sets will require better constrained models of the joint elastic‐electrical properties of reservoir rocks. Various effective medium models were compared to a novel laboratory data set of elastic velocity and electrical resistivity (obtained on 67 reservoir sandstone samples saturated with 35 g/l brine at a differential pressure of 8 MPa) with mixed results. Hence, we developed a new three‐phase effective medium model for sandstones with pore‐filling clay minerals based on the combined self‐consistent approximation and differential effective medium model. We found that using a critical porosity of 0.5 and an aspect ratio of 1 for all three components, the proposed model gave accurate model predictions of the observed magnitudes of P‐wave velocity and electrical resistivity and of the divergent trends of clean and clay‐rich sandstones at higher porosities. Using only a few well‐constrained input parameters, the new model offers a practical way to predict in situ porosity and clay content in brine saturated sandstones from co‐located P‐wave velocity and electrical resistivity data sets. 相似文献
14.
裂缝型储层的描述包括预测裂缝分布特征和识别裂隙充填物.依据等效介质理论计算的纵波速度随裂缝密度的增大而减小.正演地震记录显示,裂缝介质含气时反射振幅最大,且变化程度比含油或含水时大.叠前方位AVO反演所得的各向异性梯度Bani与裂缝密度成正比,可用于描述有效裂缝发育强度.对于不同的裂缝密度,各向异性梯度Bani与各向同性梯度Biso的比值I(1)fluid近似为常数,且对流体敏感.经裂缝纵横比和背景介质拉梅常数修正后,流体因子Ifluid既不随纵横比变化,又不受背景介质的影响,是裂缝型储层敏感的流体识别因子.在塔里木盆地塔北哈拉哈塘地区热瓦普区块碳酸盐岩储层裂缝发育区域,运用该参数在井点处的流体识别效果与钻井结果一致. 相似文献
15.
The first part of the contribution deals with the generalization of the solution given by Sharpe and states the elements of the mathematical model of the explosion generating longitudinal waves. The generalization of Sharpe's solution consists in finding out the response of the medium to a pressure p(t) applied at the source, for any value of the ratio K=Vp/Vs covering the range √2 ÷∞. The second part contains the results of the calculation and design of three electronic analog models of the explosion process in rocks. The first is represented by electrical circuits separated by emitter follower circuits. The scheme of the second model has electrical circuits and elements of operational calculus (integrator, summation instrument). The electrical circuits are represented by the two filters simulating the selective effect of the explosion in rocks. The third model is a logical programming scheme of the problem on an analog computer. For the calculus of the electrical parameters of the three schemes we have taken into account scaling of the physical and geometrical parameters of the medium and of the explosion which should ensure the simulation of the explosion process in rocks of all kinds of importance in seismic prospecting. 相似文献
16.
A two-phase numerical model using Smoothed Particle Hydrodynamics (SPH) is applied to two-phase liquid-sediments flows. The absence of a mesh in SPH is ideal for interfacial and highly non-linear flows with changing fragmentation of the interface, mixing and resuspension. The rheology of sediment induced under rapid flows undergoes several states which are only partially described by previous research in SPH. This paper attempts to bridge the gap between the geotechnics, non-Newtonian and Newtonian flows by proposing a model that combines the yielding, shear and suspension layer which are needed to predict accurately the global erosion phenomena, from a hydrodynamics prospective. The numerical SPH scheme is based on the explicit treatment of both phases using Newtonian and the non-Newtonian Bingham-type Herschel-Bulkley-Papanastasiou constitutive model. This is supplemented by the Drucker-Prager yield criterion to predict the onset of yielding of the sediment surface and a concentration suspension model. The multi-phase model has been compared with experimental and 2-D reference numerical models for scour following a dry-bed dam break yielding satisfactory results and improvements over well-known SPH multi-phase models. With 3-D simulations requiring a large number of particles, the code is accelerated with a graphics processing unit (GPU) in the open-source DualSPHysics code. The implementation and optimisation of the code achieved a speed up of x58 over an optimised single thread serial code. A 3-D dam break over a non-cohesive erodible bed simulation with over 4 million particles yields close agreement with experimental scour and water surface profiles. 相似文献
17.
Quantifying Damage, Saturation and Anisotropy in Cracked Rocks by Inverting Elastic Wave Velocities 总被引：1，自引：0，他引：1
Alexandre Schubnel Philip M. Benson Ben D. Thompson Jim F. Hazzard R. Paul Young 《Pure and Applied Geophysics》2006,163(5-6):947-973
Crack damage results in a decrease of elastic wave velocities and in the development of anisotropy. Using non-interactive
crack effective medium theory as a fundamental tool, we calculate dry and wet elastic properties of cracked rocks in terms
of a crack density tensor, average crack aspect ratio and mean crack fabric orientation from the solid grains and fluid elastic
properties. Using this same tool, we show that both the anisotropy and shear-wave splitting of elastic waves can be derived.
Two simple crack distributions are considered for which the predicted anisotropy depends strongly on the saturation, reaching
up to 60% in the dry case. Comparison with experimental data on two granites, a basalt and a marble, shows that the range
of validity of the non-interactive effective medium theory model extends to a total crack density of approximately 0.5, considering
symmetries up to orthorhombic. In the isotropic case, Kachanov's (1994) non-interactive effective medium model was used in
order to invert elastic wave velocities and infer both crack density and aspect ratio evolutions. Inversions are stable and
give coherent results in terms of crack density and aperture evolution. Crack density variations can be interpreted in terms
of crack growth and/or changes of the crack surface contact areas as cracks are being closed or opened respectively. More
importantly, the recovered evolution of aspect ratio shows an exponentially decreasing aspect ratio (and therefore aperture)
with pressure, which has broader geophysical implications, in particular on fluid flow. The recovered evolution of aspect
ratio is also consistent with current mechanical theories of crack closure. In the anisotropic cases—both transverse isotropic
and orthorhombic symmetries were considered—anisotropy and saturation patterns were well reproduced by the modelling, and
mean crack fabric orientations we recovered are consistent with in situ geophysical imaging.
Our results point out that: (1) It is possible to predict damage, anisotropy and saturation in terms of a crack density tensor
and mean crack aspect ratio and orientation; (2) using well constrained wave velocity data, it is possible to extrapolate
the contemporaneous evolution of crack density, anisotropy and saturation using wave velocity inversion as a tool; 3) using
such an inversion tool opens the door in linking elastic properties, variations to permeability. 相似文献
18.
Mass and heat transfer occurring across phase-interfaces in multi-phase flow in porous media are mostly approximated using equilibrium relationships or empirical kinetic models. However, when the characteristic time of flow is smaller than that of mass or heat transfer, non-equilibrium situations may arise. Commonly, empirical approaches are used in such cases. There are only few works in the literature that use physically-based models for these transfer terms. In fact, one would expect physical approaches to modeling kinetic interphase mass and heat transfer to contain the interfacial area between the phases as a variable. Recently, a two-phase flow and solute transport model was developed that included interfacial area as a state variable [36]. In that model, interphase mass transfer was modeled as a kinetic process. 相似文献
19.
This paper presents a Bayesian Monte Carlo method for evaluating the uncertainty in the delineation of well capture zones and its application to a wellfield in a heterogeneous, multiaquifer system. In the method presented, Bayes' rule is used to update prior distributions for the unknown parameters of the stochastic model for the hydraulic conductivity, and to calculate probability-based weights for parameter realizations using head residuals. These weights are then assigned to the corresponding capture zones obtained using forward particle tracking. Statistical analysis of the set of weighted protection zones results in a probability distribution for the capture zones. The suitability of the Bayesian stochastic method for a multilayered system is investigated, using the wellfield Het Rot at Nieuwrode, Belgium, located in a three-layered aquifer system, as an example. The hydraulic conductivity of the production aquifer is modeled as a spatially correlated random function with uncertain parameters. The aquitard and overlying unconfined aquifer are assigned random, homogeneous conductivities. The stochastic results are compared with deterministic capture zones obtained with a calibrated model for the area. The predictions of the stochastic approach are more conservative and indicate that parameter uncertainty should be taken into account in the delineation of well capture zones. 相似文献