Publications
254 results found
Yang C, Grattoni CA, Muggeridge AH, et al., 2000, Flow of Water Through Elastically Deformable Polymer Gels, European Conference on Mathematics of Oil Recovery (ECMOR)
Sisavath S, Jing XD, Zimmerman RW, 2000, Effect of stress on the hydraulic conductivity of rock pores, PHYSICS AND CHEMISTRY OF THE EARTH PART A-SOLID EARTH AND GEODESY, Vol: 25, Pages: 163-168, ISSN: 1464-1895
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- Citations: 28
Zambrano J, Zimmerman RW, Gringarten AC, 2000, Influence of geological features on well test behavior, 2000 SPE Asia Pacific Conference on Integrated Modelling for Asset Management SPE 59398, Yokohama, Japan, 25-26 April (2000)
Romero CE, Carter J, Gringarten AC, et al., 2000, A modified genetic algorithm for reservoir characterisation, SPE Int. Oil Gas Conf, Beijing, 7-10 Nov
Zimmerman RW, 2000, Micromechanics of poroelastic rocks, Heterogeneous Media: Modelling, Methods, and Simulation, Editors: Markov, Preziosi, Boston, Publisher: Birkhauser, ISBN: 9780817640835
Zambrano J, Zimmerman RW, Gringarten AC, 2000, Influence of Geological Features on Well Test Behavior, 2000 SPE Asia Pacific Conference on Integrated Modelling for Asset Management SPE 59398, Yokohama, Japan, 25-26 April (2000)
Zimmerman RW, 2000, Implications of static poroelasticity for reservoir compaction, Rotterdam, 4th north american rock mechanics symposium (narms 2000) JUL 31-AUG 03, 2000 SEATTLE, WASHINGTON, Publisher: A A Balkema, Pages: 169-172
Al-Sharji HH, Grattoni CA, Dawe RA, et al., 1999, Pore-scale study of the flow of oil and water through polymer gels
High water production is one of the major problems faced by the petroleum industry. One method of controlling water production that has been used with some success is to inject polymer gels into the near-well bore formation. However, polymer gel injections are not always successful, in part because the exact mechanisms by which they reduce water permeability more so than oil permeability are not understood. To elucidate the fundamental mechanisms involved in disproportionate permeability reduction (DPR), we have conducted a series of experiments on flow of water and oil through bulk polymer gels and through polymer-filled glass micromodels. Flow experiments through weak polyacrylamide-based gels have been performed to obtain the gel permeabilities by using different test conditions: constant pressure, constant flow rate, and the falling head method. Gel permeability was found to vary with flowrate, according to a power-law that holds over several orders of magnitude of velocity. This was true for both water and oil flow, although with different pre-factors and exponents. Water flows through the gel matrix as if flowing through a porous medium, whereas the oil pushes its way through in the form of immiscible drops or filaments. Mathematical models to quantify these flows are currently being developed.
Zimmerman RW, Lutz MP, 1999, Thermal stresses and thermal expansion in a uniformly heated functionally graded cylinder, JOURNAL OF THERMAL STRESSES, Vol: 22, Pages: 177-188, ISSN: 0149-5739
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- Citations: 193
Al-Sharji HH, Grattoni CA, Dawe RA, et al., 1999, Pore-scale study of oil and water flow through polymer gels, Journal of Petroleum Technology, Vol: 51, ISSN: 0149-2136
Yeo IW, Zimmerman RW, 1998, Efect of shear displacement on the aperture and permeability of a rock fracture, International Journal of Rock Mechanics, Vol: 35, Pages: 1051-1070
del Rio JA, Zimmerman RW, Dawe RA, 1998, Formula for the conductivity of a two-component material based on the reciprocity theorem, Solid State Communications, Vol: 106, Pages: 183-186
Schlueter EM, Zimmerman RW, Witherspoon PA, et al., 1997, The fractal dimension of pores in sedimentary rocks and its influence on permeability, Engineering Geology, Vol: 48, Pages: 199-215
Lutz MP, Monteiro PJM, Zimmerman RW, 1997, Inhomogeneous interfacial transition zone model for the bulk modulus of mortar, Cement and Concrete Research, Vol: 27, Pages: 1113-1122
Lutz MP, Monteiro PJM, Zimmerman RW, 1996, Inhomogeneous interfacial transition zone model for the elastic moduli of concrete, Pages: 1246-1255
An inhomogeneous interfacial transition zone model has been developed for the macroscopic elastic moduli of concrete. Each inclusion (fine or coarse aggregate) is assumed to be spherical, and surrounded by an interfacial transition zone (ITZ) in which the elastic moduli vary smoothly as a function of radial distance from the center of the inclusion, according to a power law. The exponent in the power law can be chosen based on the estimated thickness of the ITZ, or by fitting the power law to measured porosity profiles. For this model, an analytical expression has been found for the overall effective bulk modulus. The macroscopic bulk modulus of the concrete depends on known properties such as the elastic moduli of the bulk cement paste and the inclusions, the volume fraction of the inclusions, as well as on the elastic moduli at the interface. By comparing the model predictions to measurements of the macroscopic elastic moduli, estimates can be obtained of the elastic moduli at the interface. This model affords a simple, non-destructive method for estimating the mechanical properties within the interfacial transition zone.
Lutz MP, Zimmerman RW, 1996, Thermal stresses and effective thermal expansion coefficient of a functionally-gradient sphere, Journal of Thermal Stresses, Vol: 19, Pages: 39-54
Zimmerman RW, Bodvarsson GS, 1996, Hydraulic conductivity of rock fractures, Transport in Porous Media, Vol: 23, Pages: 1-30
Yeo IW, Zimmerman RW, de Freitas MH, 1996, Design and analysis of an experimental system to measure directional permeabilities of a rock fracture under normal and shear loading, International Symposium of the International Society of Rock Mechanics, Torino, Italy, Pages: 1223-1227
Zimmerman RW, Bodvarsson GS, 1996, Effective transmissivity of a two-dimensional fracture network, International Journal of Rock Mechanics, Vol: 33, Pages: 433-438
Zimmerman RW, Hadgu T, Bodvarsson GS, 1996, A new lumped-parameter model for flow in unsaturated dual-porosity media, Advances in Water Resources, Vol: 19, Pages: 317-327
Lutz MP, Zimmerman RW, 1996, Effect of the interphase zone on the bulk modulus of a particulate composite, Journal of Applied Mechanics, Vol: 63, Pages: 855-861
Zimmerman RW, 1996, Effective conductivity of a two-dimensional medium containing elliptical inclusions, Proceedings of the Royal Society, Vol: A452, Pages: 1713-1727
Zimmerman RW, 1995, Effective block size for imbibition and absorption in dual-porosity media, GEOPHYS RES LETTS, Vol: 22, Pages: 1461-1464
A theoretical study is presented of liquid imbibition and solute absorption from a fracture network into a collection of matrix blocks of varying sizes and shapes. An individual irregularly-shaped matrix block can be modeled with reasonable accuracy using the results for a spherical matrix block, by defining an effective radius ($) over tilde a = 3V/A, where V is the volume of the block and A is its surface area. In the early-time regime, a collection of spherical blocks of different sizes can be replaced by an equivalent spherical block with a radius of a(eq) = < a(-1) >(-1), where the average is taken on a volumetrically-weighted basis. In the long-time limit, where no equivalent radius can rigorously be defined, asymptotic expressions are derived for the cumulative uptake as a function of the mean and the standard deviation of the radius distribution function, for both normal and lognormal radius distributions.
HADGU T, ZIMMERMAN RW, BODVARSSON GS, 1995, COUPLED RESERVOIR-WELLBORE SIMULATION OF GEOTHERMAL RESERVOIR BEHAVIOR, GEOTHERMICS, Vol: 24, Pages: 145-166, ISSN: 0375-6505
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- Citations: 21
Hadgu T, Zimmerman RW, Bodvarsson GS, 1995, Coupled reservoir-wellbore simulation of geothermal reservoir behavior, GEOTHERMICS, Vol: 2, Pages: 145-166
The reservoir simulator TOUGH and the wellbore simulator WFSA have been coupled to model Row of geothermal brine in the reservoir as well as in the wellbore, An outline of the structure of the two computer codes is given, together with the relevant equations. A new module, COUPLE, has been written to serve as an interface between TOUGH and WFSA. Two sample problems are given to illustrate the use of the coupled codes. One of these problems compares the results of the new simulation method to those obtained by using the deliverability option in TOUGH. The coupled computing procedure is shown to simulate more accurately the behavior of a geothermal reservoir under exploitation.
Zimmerman RW, Bodvarsson GS, 1995, Simple procedure for estimating the effective hydraulic conductivity of a two-dimensional saturated or partly-saturated fracture network, Pages: 26-28
The effective medium theory developed by Kirkpatrick has been used as the basis for a procedure for finding the effective gridblock-scale conductivity of a two-dimensional fracture network. In contrast to computationally-intensive flow simulations, the proposed procedure requires only the solution of a single nonlinear equation. The method has been tested against some previously published numerical simulations of flow through saturated and unsaturated networks, and in both cases yields reasonably accurate predictions of the macroscopic hydraulic conductivity.
Schlueter EM, Zimmerman RW, Cook NGW, et al., 1994, Perimeter-area power-law relationship of pores in sedimentary rocks and implications for permeability, 1994 SEG Annual Meeting, Pages: 315-318
© 1994 SEG Annual Meeting. All Rights Reserved. Perimeter-area power-law relationships of pores in five sedimentary rocks are determined from scanning electron photomi-crographs of thin sections. These relationships for the pores of four sandstones were found to lie between 1.43 and 1.49, while that of an Indiana limestone was found to be 1.67. We discuss how the perimeter-area power-law relationship of pores, along with a pore-size distribution, can be used to estimate the hydraulic permeability.
ZIMMERMAN RW, MYER LR, COOK NGW, 1994, GRAIN AND VOID COMPRESSION IN FRACTURED AND POROUS ROCKS, INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES & GEOMECHANICS ABSTRACTS, Vol: 31, Pages: 179-184, ISSN: 0148-9062
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- Citations: 18
Zimmerman RW, 1994, Behavior of the poisson ratio of a two-phase composite material in the high-concentration limit, Applied Mechanics Reviews, Vol: 47, Pages: 38-44, ISSN: 0003-6900
The behavior of the Poisson ratio of a material filled with spherical inclusions is studied in the high-concentration limit, using the Mori-Tanaka and the differential effective medium theories. When the inclusions are either much stiffer or much softer than the matrix, both theories predict the existence of a boundary layer near c = 1 in the graph of the Poisson ratio v as a function of inclusion concentration c. As c increases, v first approaches some fixed point v* that depends only on the matrix properties. In a localized region near c = 1, v then varies rapidly so as to equal the Poisson ratio of the inclusions at c = 1. The results therefore show a qualitative distinction between, for example, the effect of very hard inclusions and infinitely rigid inclusions. The results also illustrate the extent to which the Poisson ratio fails to obey a mixing law of the Voigt or Reuss type, in that the effective Poisson ratio is not bounded between the Poisson ratios of the matrix and inclusion phases. © American Society of Mechanical Engineers.
Schlueter EM, Zimmerman RW, 1993, Network model of sandstone permeability, Pages: 207-212
A model is developed that allows accurate prediction of the hydraulic permeability of a core sample of sedimentary rock. The pore structure is idealized as consisting of a cubic network of pore tubes. The individual conductance of each tube is estimated from its area and perimeter, using the hydraulic radius approximation. Variations in the pore diameter along the length of the tube are accounted for with a 'constriction factor' whose derivation is based on laminar flow through an irregular tube. The areas and perimeters of the individual pores are estimated from image analysis of scanning electron micrographs of thin sections, with appropriate stereological corrections. Effective medium theory is used to find the effective single-tube conductance, based on the distribution of individual conductances. This procedure is applied to four sandstones, with the predicted permeabilities in each case within a factor of two of the measured values.
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