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Porosity and pore structure from acoustic well logging data
338A used to process the digital data. Multilayer images were produced on which supervised and unsupervised classification systems were applied to describe such features as matrix, pores, clay coatings, and quartz. Best results were obtained using a combination of plain transmitted light and circularly polarised light.
936039 Porosity and pore structure from acoustic well logging data Tao, G; King, M S Geophys Prospect V41, N4, May 1993, P435-451 A new acoustic velocity to porosity transform is presented, based on a velocity model by Kuster and Toksoz, for improved understanding of pore structure by inverting P and S wave data obtained from sonic logs. Pore structure as well as total porosity can be taken into account. Calculations for sedimentary rocks using this procedure are presented and compared to those from the time-average equation. The potential for extending the method to more complex lithologies and shaly rocks is discussed.
936O4O Fractai Menger Sponge and Sierpinski Carpet as models for reservoir rock/pore systems: II. Image analysis of natural fractal reservoir rocks Garrison, J R; Pearn, W C; yon Rosenberg, D U In Situ V17, N1, 1993, P1-53 Reservoir rock/pore systems are considered as natural fractal objects and compared to two well known regular fractals. In order to investigate the fractal characteristics of natural reservoir rocks and assess the validity of the Sierpinski Carpet model, SEM image analysis was carried out on samples of sandstone, dolomite, and limestone reservoir rocks. Two types of multiple fractal rock/pore system were identified. The pseudorandom Sierpinski Carpet is considered adequate to model reservoir rocks in two dimensions.
936041 Fractai Menger Sponge and Sierpinski Carpet as models for reservoir rock/pore systems: III. Stochastic simulation of natural fractal processes Garrison, J R; Pearn, W C; von Rosenberg, D U In Situ V17, N2, 1993, P143-182 Reservoir rock/pore systems are considered as natural fractal objects and compared to two well known regular fractals. Geometry of the rock/pore systems can be described in terms of apparent fractal dimension determined from diameter-number distributions. Two types of multiple fractal rock/pore system have been identified. To further investigate the fractal nature of natural reservoir rocks and validate the Sierpinski Carpet model presented in paper I and analogies and interpretations developed in paper II, a computer algorithm for stochastic modelling or simulation of fractal pore diameter distributions is presented.
936042 Nondestructive measurement of fracture aperture in crystalline rock cores using X ray computed tomography Johns, R A; Steude, J S; Castanier, L M; Roberts, P V J Geophys Res V98, NB2, Feb 1993, P1889-1900 The variability of the aperture field in natural fractures in two granite cores was characterised using a medical and an industrial scanner. A quantitative method has been developed to measure fracture aperture thickness and reconstruct the aperture distribution in the cores with spatial resolution 1.4mm by 1.4mm by 5ram. Results show fracture aperture varies over a
range of several orders of magnitude and approximately follows a log-normal distribution in one of the cores. Using tracers, it is possible to image flow distribution and fingering in the cores.
936043 Magnetic pore fabric analysis: verification through image autocorrelation Pfleiderer, S; Halls, H C J Geophys Res V98, NB3, March 1993, P4311-4316 A new method to study pore geometry of sandstones is presented in which the samples are impregnated with a magnetic solution (ferrofluid) and the anisotropic magnetic susceptibility (AMS) is subsequently measured and analysed. Interpretations based on AMS are compared to pore structure shapes from image analysis of thin sections. Limits of applicability of the new technique for interpretation of anisotropic petrophysical properties are discussed.
936044 Characterisation of non-spherical particles from their packing behaviour Yu, A B; Standish, N Powder Technol V74, N3, March 1993, P205-213 Non-spherical particles are usually characterised in terms of equivalent spherical diameter, but such parameters developed to date do not satisfactorily characterise the structural properties of particulate materials. An equivalent packing diameter is here defined on the basis of the similarity between packing systems of spherical and non-spherical particles, and is empirically related to sphericity and some commonly used equivalent particle diameters (volume, surface, and surface volume diameters). The relation between porosity and sphericity of monosized particles is formulated using published data.
936045 Change in pore size distribution of peat in shear processes Yamaguchi, H; Hashizume, Y; Ikenaga, H Soils Found V32, N4, Dec 1992, PI-16 Saturated remoulded specimens of peat, normally or overconsolidated under isotropic stress conditions, were subject to drained triaxial shear tests. Specimens were vacuum freeze dried immediately after testing and mercury porosimetry carried out. Pore size distributions observed are discussed with reference to changes in pore structure and drained shear behaviour. Effects of strain rate on pore structure were investigated for normally consolidated specimens only. Changes in pore structure corresponded to volume changes during shear and were considerably influenced by degree of overconsolidation.
936046 Interpretation of capillary pressure curves using invasion percolation theory Zhou, D; Stenby, E H Trans Porous Media Vll, N1, April 1993, P17-31 The concept of invasion percolation is introduced and used to develop a new model to obtain pore size distributions from capillary pressure measurements in porous media. Improvement over use of the conventional percolation model is obtained as physical trapping of the wetting phase can be taken into account. The new model is evaluated against a data set of over 100 capillary pressure curves from consolidated media. The pore-throat size distribution obtained using the new model is broader than that from conventional percolation and capillary tube models.
© 1993 Pergamon Press Ltd. Reproduction not permitted
936039 Porosity and pore structure from acoustic well logging data Tao, G; King, M S Geophys Prospect V41, N4, May 1993, P435-451 A new acoustic velocity to porosity transform is presented, based on a velocity model by Kuster and Toksoz, for improved understanding of pore structure by inverting P and S wave data obtained from sonic logs. Pore structure as well as total porosity can be taken into account. Calculations for sedimentary rocks using this procedure are presented and compared to those from the time-average equation. The potential for extending the method to more complex lithologies and shaly rocks is discussed.
936O4O Fractai Menger Sponge and Sierpinski Carpet as models for reservoir rock/pore systems: II. Image analysis of natural fractal reservoir rocks Garrison, J R; Pearn, W C; yon Rosenberg, D U In Situ V17, N1, 1993, P1-53 Reservoir rock/pore systems are considered as natural fractal objects and compared to two well known regular fractals. In order to investigate the fractal characteristics of natural reservoir rocks and assess the validity of the Sierpinski Carpet model, SEM image analysis was carried out on samples of sandstone, dolomite, and limestone reservoir rocks. Two types of multiple fractal rock/pore system were identified. The pseudorandom Sierpinski Carpet is considered adequate to model reservoir rocks in two dimensions.
936041 Fractai Menger Sponge and Sierpinski Carpet as models for reservoir rock/pore systems: III. Stochastic simulation of natural fractal processes Garrison, J R; Pearn, W C; von Rosenberg, D U In Situ V17, N2, 1993, P143-182 Reservoir rock/pore systems are considered as natural fractal objects and compared to two well known regular fractals. Geometry of the rock/pore systems can be described in terms of apparent fractal dimension determined from diameter-number distributions. Two types of multiple fractal rock/pore system have been identified. To further investigate the fractal nature of natural reservoir rocks and validate the Sierpinski Carpet model presented in paper I and analogies and interpretations developed in paper II, a computer algorithm for stochastic modelling or simulation of fractal pore diameter distributions is presented.
936042 Nondestructive measurement of fracture aperture in crystalline rock cores using X ray computed tomography Johns, R A; Steude, J S; Castanier, L M; Roberts, P V J Geophys Res V98, NB2, Feb 1993, P1889-1900 The variability of the aperture field in natural fractures in two granite cores was characterised using a medical and an industrial scanner. A quantitative method has been developed to measure fracture aperture thickness and reconstruct the aperture distribution in the cores with spatial resolution 1.4mm by 1.4mm by 5ram. Results show fracture aperture varies over a
range of several orders of magnitude and approximately follows a log-normal distribution in one of the cores. Using tracers, it is possible to image flow distribution and fingering in the cores.
936043 Magnetic pore fabric analysis: verification through image autocorrelation Pfleiderer, S; Halls, H C J Geophys Res V98, NB3, March 1993, P4311-4316 A new method to study pore geometry of sandstones is presented in which the samples are impregnated with a magnetic solution (ferrofluid) and the anisotropic magnetic susceptibility (AMS) is subsequently measured and analysed. Interpretations based on AMS are compared to pore structure shapes from image analysis of thin sections. Limits of applicability of the new technique for interpretation of anisotropic petrophysical properties are discussed.
936044 Characterisation of non-spherical particles from their packing behaviour Yu, A B; Standish, N Powder Technol V74, N3, March 1993, P205-213 Non-spherical particles are usually characterised in terms of equivalent spherical diameter, but such parameters developed to date do not satisfactorily characterise the structural properties of particulate materials. An equivalent packing diameter is here defined on the basis of the similarity between packing systems of spherical and non-spherical particles, and is empirically related to sphericity and some commonly used equivalent particle diameters (volume, surface, and surface volume diameters). The relation between porosity and sphericity of monosized particles is formulated using published data.
936045 Change in pore size distribution of peat in shear processes Yamaguchi, H; Hashizume, Y; Ikenaga, H Soils Found V32, N4, Dec 1992, PI-16 Saturated remoulded specimens of peat, normally or overconsolidated under isotropic stress conditions, were subject to drained triaxial shear tests. Specimens were vacuum freeze dried immediately after testing and mercury porosimetry carried out. Pore size distributions observed are discussed with reference to changes in pore structure and drained shear behaviour. Effects of strain rate on pore structure were investigated for normally consolidated specimens only. Changes in pore structure corresponded to volume changes during shear and were considerably influenced by degree of overconsolidation.
936046 Interpretation of capillary pressure curves using invasion percolation theory Zhou, D; Stenby, E H Trans Porous Media Vll, N1, April 1993, P17-31 The concept of invasion percolation is introduced and used to develop a new model to obtain pore size distributions from capillary pressure measurements in porous media. Improvement over use of the conventional percolation model is obtained as physical trapping of the wetting phase can be taken into account. The new model is evaluated against a data set of over 100 capillary pressure curves from consolidated media. The pore-throat size distribution obtained using the new model is broader than that from conventional percolation and capillary tube models.
© 1993 Pergamon Press Ltd. Reproduction not permitted