Publications
254 results found
David EC, Zimmerman RW, 2011, Compressibility and shear compliance of spheroidal pores: Exact derivation via the Eshelby tensor, and asymptotic expressions in limiting cases, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, Vol: 48, Pages: 680-686, ISSN: 0020-7683
- Author Web Link
- Cite
- Citations: 56
Wuthicharn K, Zimmerman RW, 2011, Shape factors for irregularly shaped matrix blocks, Pages: 474-482
The shape factor that appears in dual-porosity models of single-phase flow in naturally fractured reservoirs is investigated. Previously derived analytical expressions for a few simple geometries (spheres, cubes, slabs, etc.) are first reviewed. A general numerical procedure is presented that allows the shape factor of an arbitrarily shaped block to be found using a fine-grid simulation of flow into a single matrix block with constant-pressure boundary conditions. From these various results, a scaling law is suggested that expresses the shape factor in terms of the block's volume V, the block's outer surface area S, and a diffusion length l. This expression is α = 5S/Vγ, where γ = V1/3 for a three-dimensional block, and γ = A1/2 for a two-dimensional prismatic block with cross-sectional area A. For all cases analyzed, this expression predicts the shape factor within an error of less than 10%. This seems to be the first accurate, general expression available for estimating the shape factors of irregularly shaped matrix blocks such as are formed by the intersection of realistic fracture networks. Copyright 2011, Society of Petroleum Engineers.
Wong HS, Pappas AM, Zimmerman RW, et al., 2011, Effect of entrained air voids on the microstructure and mass transport properties of concrete, Cem. Concr. Res., Vol: 41, Pages: 1067-1077
Paluszny A, Zimmerman RW, 2011, Numerical simulation of multiple 3D fracture propagation using arbitrary meshes, Computer Methods in Applied Mechanics and Engineering, Vol: 200, Pages: 953-966
Sonmez H, Kasapoglu KE, Coskun A, et al., 2010, A conceptual empirical approach for the overall strength of unwelded bimrocks, Pages: 357-360
Design and engineering facilities are often constructed in complex geological mixtures or fragmented rocks such as melanges, fault rocks, coarse pyroclastic rocks, breccias and sheared serpentines. These types of geological materials are generally chaotic and mechanically and/or spatially heterogeneous rock masses, which are composed of relatively strong rock inclusions, surrounded by weaker matrix, and may be considered as bimrocks (block-in-matrix-rocks; Medley, 1994). The preparation of standard and representative cores from these types of rock masses for conventional laboratory experiments is almost impossible. In the literature, there are a few attempts to overcome this difficulty by developing empirical approaches based on case histories and laboratory studies on bimrocks. However, despite these attempts, there is no widely accepted empirical approach in the rock mechanics community. In this study, some conceptual equations, which are open to improvement, were generated by considering literature findings to predict strength of unwelded bimrocks. © 2010 Taylor & Francis Group, London.
Tong F, Jing L, Zimmerman RW, 2010, A fully coupled thermo-hydro-mechanical model for simulating multiphase flow, deformation and heat transfer in buffer material and rock masses, INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES, Vol: 47, Pages: 205-217, ISSN: 1365-1609
- Author Web Link
- Cite
- Citations: 95
Mathias SA, Hardisty PE, Trudell MR, et al., 2010, Screening and selection of sites for CO<sub>2</sub> sequestration based on pressure buildup (vol 3, pg 577, 2009), INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 4, Pages: 108-109, ISSN: 1750-5836
- Author Web Link
- Cite
- Citations: 5
Leung CTO, Zimmerman RW, 2010, Estimating the hydraulic conductivity of two-dimensional fracture networks using effective medium theory and power-law averaging, European Rock Mechanics Symposium (EUROCK 2010), Publisher: CRC PRESS-TAYLOR & FRANCIS GROUP, Pages: 243-246
- Author Web Link
- Cite
- Citations: 1
Zimmerman RW, 2010, Some rock mechanics issues in petroleum engineering, European Rock Mechanics Symposium (EUROCK 2010), Publisher: CRC PRESS-TAYLOR & FRANCIS GROUP, Pages: 39-44
- Author Web Link
- Cite
- Citations: 1
Tong F, Jing L, Zimmerman RW, 2009, An effective thermal conductivity model of geological porous media for coupled thermo-hydro-mechanical systems with multiphase flow, INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES, Vol: 46, Pages: 1358-1369, ISSN: 1365-1609
- Author Web Link
- Cite
- Citations: 113
Tong F, Jing L, Zimmerman RW, 2009, A fully-coupled finite element code for modeling thermo-hydro-mechanical processes in porous geological media
This paper describes a new FEM code for modeling coupled thermo-hydro-mechanical processes in porous geological media. For three-dimensional problems, six governing equations, which are based on the conservation equations of momentum, mass, and energy, are presented to describe the coupled THM processes. The three displacement components, the temperature, the pore fluid pressure and the porosity are chosen as the six primary variables. The governing continuum equations are discretized in space by using the Galerkin finite element formulation, and are discretized in time by one-dimensional finite difference scheme. This leads to a large non-symmetric matrix equation that has many small entries along its diagonal, and is therefore ill-conditioned. For efficient equation solution, some special numerical techniques are used in the code in order to deal with the problem of a large non-symmetric ill-conditioned matrix equation. The code was validated against several classical analytical solutions to problems in poroelasticity and thermoelasticity, and tested against a benchmark laboratory experiment that was performed in the Polytechnic University of Catalonia (UPC), Spain. Copyright 2009 ARMA, American Rock Mechanics Association.
Al-Ajmi AM, Zimmerman RW, 2009, A new well path optimization model for increased mechanical borehole stability, JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING, Vol: 69, Pages: 53-62, ISSN: 0920-4105
- Author Web Link
- Cite
- Citations: 60
Tong F, Jing L, Zimmerman RW, 2009, Modeling multiphase flow, deformation and heat transfer in buffer
This paper presents a new FEM approach and computer code for modeling fully coupled thermo-hydro-mechanical processes associated with underground nuclear waste repositories. The governing equations are based on the theory of mixtures applied to the multiphysics of porous media, considering solid-phase deformation, liquid-phase flow, gas flow, heat transport, thermally-induced water flow, phase change of water, and swelling deformation in buffer materials. For three-dimensional problems, three displacement components, water pressure, gas pressure, vapor pressure and porosity are chosen as the eight primary variables. The code was tested against a benchmark test that was performed in laboratory conditions on vertical cylindrical columns of compacted MX-80 bentonite by the French Commission of Atomic Energy from 2003 to 2004. The comparison with the benchmark tests shows good agreement between the numerical predictions and the measured data, thus providing a partial validation of our new code. Discussion of outstanding issues and conclusions are presented at the end of the paper.
Wong HS, Zobel M, Buenfeld NR, et al., 2009, Influence of the interfacial transition zone and microcracking on the diffusivity, permeability and sorptivity of cement-based materials after drying, Mag. Concr. Res., Vol: 61, Pages: 571-589
Zimmerman RW, 2009, On the Analogy between Poroelasticity and Thermoelasticity, 4th Biot Conference on Poromechanics, Publisher: DESTECH PUBLICATIONS, INC, Pages: 531-536
Mathias SA, Hardisty PE, Trudell MR, et al., 2009, Approximate solutions for pressure buildup during CO2 injection in brine aquifers, TRANSPORT POROUS MED, Vol: 79, Pages: 265-284, ISSN: 0169-3913
Mathias SA, Hardisty PE, Trudell MR, et al., 2009, Screening and selection of sites for CO2 sequestration based on pressure buildup, INT J GREENH GAS CON, Vol: 3, Pages: 577-585, ISSN: 1750-5836
Zimmerman RW, 2008, A simple model for coupling between the normal stiffness and the hydraulic transmissivity of a fracture
A simple model of a rock fracture is developed. The void space of the fracture is assumed to consist of parallel, periodically spaced tubular channels of elliptical cross-section. The apertures of the channels follow some arbitrary statistical distribution law. The normal stiffness of the fracture, and the hydraulic transmissivity of the fracture, can then be related to the aperture distribution function. The model is tested by inverting stress-strain data from a naturally-occurring fracture in granite to determine the aperture distribution function, and then using this aperture distribution function to predict the variation of permeability with stress. The predicted variation of transmissivity with stress shows good agreement with the measured values. © 2008, ARMA, American Rock Mechanics Association.
Matthews JD, Carter JN, Zimmerman RW, 2008, Using Drillstem and Production Tests To Model Reservoir Relative Permeabilities, 2007 SPE Offshore Europe Conference, Publisher: SOC PETROLEUM ENG, Pages: 1082-1088, ISSN: 1094-6470
- Author Web Link
- Cite
- Citations: 2
Ekneligoda TC, Zimmerman RW, 2008, Shear compliance of two-dimensional pores possessing N-fold axis of rotational symmetry, PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 464, Pages: 759-775, ISSN: 1364-5021
- Author Web Link
- Cite
- Citations: 25
Matthews JD, Carter JN, Stephen KD, et al., 2008, Assessing the effect of geological uncertainty on recovery estimates in shallow-marine reservoirs: the application of reservoir engineering to the SAIGUP project, PETROLEUM GEOSCIENCE, Vol: 14, Pages: 35-44, ISSN: 1354-0793
- Author Web Link
- Cite
- Citations: 26
Manzocchi T, Carter JN, Skorstad A, et al., 2008, Sensitivity of the impact of geological uncertainty on production from faulted and unfaulted shallow-marine oil reservoirs: objectives and methods, PETROLEUM GEOSCIENCE, Vol: 14, Pages: 3-15, ISSN: 1354-0793
- Author Web Link
- Cite
- Citations: 55
Ekneligoda TC, Zimmerman RW, 2008, Boundary perturbation solution for nearly circular holes and rigid inclusions in an infinite elastic medium, JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME, Vol: 75, ISSN: 0021-8936
- Author Web Link
- Cite
- Citations: 19
Matthews JD, Carter JN, Zimmerman RW, 2008, Using drill-stem and production tests to model reservoir relative permeabilities, SPE Reservoir Evaluation and Engineering, Vol: 11, Pages: 1082-1088
Relative permeabilities are fundamental to any assessment of reserves and reservoir management. When measurements on core samples are available, however, they often predict initial water production that is not experienced by individual wells. For example, dry oil production occurs from portions of reservoirs where the local water saturation is relatively high, even though the relative permeability data would predict a water Cut ill the range of 30 to 60%. This lack of agreement means that effective reservoir management is hampered because it is difficult for simulation models to mimic the observed reservoir production without use of data that may bear little resemblance to measurements.After a brief discussion of relative permeability, the focus of this paper is first to examine the uncertainties in the data that are used for the predictions. This then provides a numerically structured approach to adjustments that need to be made to data so that history matching Of Simulation models can be achieved. The relative permeabilities, rather than saturations and fluid properties, are shown to be the least certain of the relevant data.The second focus in the paper is to explore the reasons why the relative permeability data are so uncertain. The evidence points to the fact that oil emplacement and the subsequent geological history of the reservoirs have not been considered Sufficiently in preparing core samples before making measurements. Greater reliance oil drillstem and early production tests is, therefore, crucial for deriving reservoir relative permeabilities until laboratories are able to mimic oil emplacement within rock samples as experienced in the reservoir.The main source of data is the abandoned UK North Sea reservoir Maureen (Block 16/29a). Inevitably, during the 36 years Since discovery, some data have been misplaced. Nevertheless. Sufficient data exist to highlight the potential need for a paradigm Shift in understanding how relative permeabilities should be
Jurgawczynski M, Lock PA, Jing XD, et al., 2007, Permeability predictions based on two-dimensional pore space images, Pages: 2954-2963
A model is developed that allows accurate prediction of the permeability of a core sample of sedimentary rock, based solely on two-dimensional image analysis of its pore structure. The only required input data are the areas and perimeters of the pores observed in, for example, an SEM image. The hydraulic radius approximation is used to estimate the individual pore conductances. Prior to this, stereological corrections are used to convert apparent pore geometries, and various hydraulic corrections are applied to account for converging-diverging flow paths. These various corrections are the principal and crucial differences between our approach and previous methods based on two-dimensional images. Finally, Kirkpatrick's effective medium approximation is used to find the effective value of the hydraulic conductances of the individual pores. The method has been applied to several data sets, including consolidated North Sea reservoir sandstones, outcrop sandstones, outcrop carbonates, and carbonates from Middle East oil and gas fields. The permeabilities of this entire data set range from 0.5-1377 mD, which covers a significant portion of the range of permeabilities that are relevant in reservoir engineering. In 80% of the cases, the permeabilities predicted by our method are within a factor of two of the measured values, and the predictions are within a factor of three in over 90% of the cases. The method requires minimal data manipulation and computation when compared to approaches that require three-dimensional imaging and/or full solution of the Navier-Stokes equations, and is much more accurate than primitive empirical methods such as the Kozeny-Carman equation. Aside from giving insight into the influence of pore structure on permeability, our method offers the potential of permitting permeability predictions to be made using drill cuttings, in situations where it is not possible to recover intact core. Another possible future application is to use downhole borehol
Fernlund JMR, Zimmerman RW, Kragic D, 2007, Influence of volume/mass on grain-size curves and conversion of image-analysis size to sieve size, ENGINEERING GEOLOGY, Vol: 90, Pages: 124-137, ISSN: 0013-7952
- Author Web Link
- Cite
- Citations: 51
Jaeger JC, Cook NGW, Zimmerman RW, 2007, Fundamentals of Rock Mechanics, Oxford, UK, Publisher: Blackwell, ISBN: 978-0632057597
Matthews JD, Carter JN, Zimmerman RW, 2007, Using drillstem and production tests to model reservoir relative permeabilities, Pages: 58-63
There are many examples of dry oil production from portions of reservoirs where the local water saturation is high. When relative permeability data are available, predictions of the expected water cut are not zero, but typically 30-60%. This lack of agreement means that reservoir management using simulation models is questionable because such models can only mimic the observed reservoir production using data that bear little resemblance to measurements. The first focus of this paper is to examine the uncertainties in the data that are used for the predictions. This then provides a numerically structured approach to adjustments that need to be made to data so that history matching of simulation models can be achieved. The relative permeabilities, rather than saturations and fluid properties, are shown to be the least certain of the relevant data. The second focus is to explore the reasons why the relative permeability data are so uncertain. The evidence points to the fact that oil emplacement and subsequent geological history of the reservoirs have not been considered sufficiently in preparing core samples and making measurements. Greater reliance on drill-stem and early production tests is therefore crucial for deriving reservoir relative permeabilities until laboratories are able to mimic, within rock samples, oil emplacement as experienced in the reservoir. The main source of data is from the abandoned UK North Sea reservoir (Maureen, block 16/29a). Copyright 2007, Society of Petroleum Engineers.
Yang C, Frattoni CA, Muggeridge AH, et al., 2007, Flow of water trough channels filled with in elastically-deformable polymer gels
A mathematical model is developed for the flow of water through a channel impregnated with a polymer gel. The model uses a Brinkman equation along with an experimentally-observed velocity-dependent permeability. Numerical and approximate analytical solutions are given. When combined with a mathematical analysis of oil flow through polymer gels, which is currently underway, these results should help to understand the mechanism of disproportionate permeability reduction, which is the basis of successful polymer gel treatments for water control.
David E, Zimmerman RW, 2007, Sliding crack model for the uniaxial compression of rock., 1st Canada/United States Rock Mechanics Symposium, Publisher: TAYLOR & FRANCIS LTD, Pages: 575-580
- Author Web Link
- Cite
- Citations: 4
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.