Consolidating rock-physics classics: A practical take on granular effective medium models

Allo, Fabien

doi:10.1190/tle38050334.1

Cited by 23 publications

(7 citation statements)

References 15 publications

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“…Dvorkin and Nur (1996) used the contact theory between grains from Hertz (1882) and Mindlin (1949) and rock physics bounds of Hashin-Shtrikman (1963) to propose granular effective media models. Allo (2019) proposed an extension of these models including new modeling parameters such as matrix stiffness index, cement cohesion coefficient, contact-cement fraction, and laminated clay fraction.…”

Section: R a F Tmentioning

confidence: 99%

Rock physics modeling with mineralogical inversion in sandstone reservoir

et al. 2022

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Reservoir characterization is a valuable tool for the oil and gas industry. A better understanding of the reservoir demands the integration of petrophysical properties and elastic parameters. This integration is commonly performed with the aid of rock physics models. The elastic properties of solid-phase components are important parameters for rock physics models calibration. In this paper, we use an adaptation of mineralogical inversion to estimate the volumes of quartz, feldspar, and clay minerals that incorporate previously calculated clay volume and porosity. Clay volume estimation is performed from neutron and bulk density logs. We chose this method due to the presence of feldspar minerals in the reservoirs. Our workflow consists of petrophysics properties estimation, mineralogical inversion, rock physics model calibration in Well A, and compressional-wave velocity estimation in Well B. The mineralogical inversion in Well A provided average volumes of 64% quartz and 16% feldspar and previously estimated 20% clay minerals. When applied to Well B, the calibrated soft-sand model is a better approximation for high porosity data points than the constant-cement model, and the error between original and estimated logs is about 2.9%, suggesting that the approach can be extended to other wells in the study area.

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Section: R a F Tmentioning

confidence: 99%

Rock physics modeling with mineralogical inversion in sandstone reservoir

et al. 2022

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“…A unified equation for α can be obtained by introducing a new parameter that allows to interpolate between the two cases represented by equations ( 16) and ( 18) (Allo, 2019; Table 1), but as we shall see in the examples, the velocities obtained with these two cases do not differ significantly from a practical viewpoint.…”

Section: Model 3 Generalized Gassmann (Gg) Theorymentioning

confidence: 99%

Rock acoustics of diagenesis and cementation

Carcione,

Gei,

Picotti

et al. 2021

Preprint

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We simulate the effects of diagenesis, cementation and compaction on the elastic properties of shales and sandstones with four different petro-elastical theories and a basinevolution model, based on constant heating and sedimentation rates. We consider shales composed of clay minerals, mainly smectite and illite, depending on the burial depth, and the pore space is assumed to be saturated with water at hydrostatic conditions. Diagenesis in shale (smectite/illite transformation here) as a function of depth is described by a 5th-order kinetic equation, based on an Arrhenius reaction rate. On the other hand, quartz cementation in sandstones is based on a model that estimates the volume of precipitated quartz cement and the resulting porosity loss from the temperature history, using an equation relating the precipitation rate to temperature. Effective pressure effects (additional compaction) are accounted for by using Athy equation and the Hertz-Mindlin model. The petro-elastic models yield similar seismic velocities, despite the different level of complexity and physics approaches, with increasing density and seismic velocities as a function of depth.The methodology provides a simple procedure to obtain the velocity of shales and sandstones versus temperature and pressure due to the diagenesis-cementation-compaction process.

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“…низмов и стадий деформации и условий активности разломов. Заменить модели со сложной текстурой большинства зернистых осадочных пород на модели гранулированной эффективной среды, основанные на физике случайной упаковки сфер, предложено в [8]. Физические свойства пород-коллекторов, содержащих нефть, газ или воду, зависят от минерального состава и текстуры породы, отмечается в [9].…”

Section: Introductionunclassified

Formation of synthetic structures and textures of rocks when simulating in COMSOL Multiphysics

Voznesensky

Kidima-Mbombi

2021

Min.Sci.Technol. (RUS)

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Rock texture and structure play an important role in the formation of the rock physical properties, and also carry information about their genesis. The paper deals with the simulation of geometric shapes of various structures and textures of rocks by the finite-element method (FEM). It is carried out by programmed detailing of the element properties and their spatial location in the simulated object. When programming structures, it is also possible to set the physical properties of various parts of the model, grids, initial and boundary conditions, which can be changed in accordance with the scenarios for numerical experiments. In this study, on the basis of FEM, simulation of various structures and textures of rocks with inclusions and disruptions was implemented in COMSOL Multiphysics in conjunction with Matlab. Such structures are used to conduct computer generated simulations to determine physical properties of geomaterials and study the effect on them of agents of various physical nature. The building of several models was considered: a rock specimen with inclusions in the form of ellipses of equal dimensions with different orientations; a sandstone specimen containing inclusions with high modulus of elasticity in cement matrix when deforming; a limestone specimen with fractures filled with oil and saline water when determining its specific electrical resistance. As an example of a fractured structure analysis, the influence of the filler on the electrical resistance of the limestone specimen containing a system of thin elliptical predominantly horizontal fractures was considered. The change in the lines of current flow at different ratios between the matrix and the fracture filler conductivities and their effect on the effective (averaged) conductivity of the rock specimen was clearly demonstrated. The lower conductivity of the fracture filler leads to increasing the length and decreasing the cross-section of the current flow lines that, in turn, leads to significant decrease in the conductivity of the fractured rock specimen. The higher filler conductivity results in a slight increase in the conductivity of the fractured specimen compared to that of the homogeneous isotropic specimen. The resulting structures can be used for numerical experiments to study physical properties of rocks.

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Consolidating rock-physics classics: A practical take on granular effective medium models

Cited by 23 publications

References 15 publications

Rock physics modeling with mineralogical inversion in sandstone reservoir

Rock physics modeling with mineralogical inversion in sandstone reservoir

Rock acoustics of diagenesis and cementation

Formation of synthetic structures and textures of rocks when simulating in COMSOL Multiphysics

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