Estimation of dry-rock elastic moduli based on the simulation of mud-filtrate invasion effects on borehole acoustic logs
dc.contributor.advisor | Torres-Verdin, Carlos | |
dc.creator | Odumosu, Tobiloluwa Boladun | |
dc.date.accessioned | 2017-07-11T14:40:13Z | |
dc.date.available | 2017-07-11T14:40:13Z | |
dc.date.issued | 2007-08 | |
dc.description.abstract | Reliable estimates of dry-rock elastic properties are critical to accurately interpreting the seismic response of hydrocarbon reservoirs. These estimates are needed as input for Biot-Gassmann fluid substitution calculations used in a wide range of applications for present-day reservoir characterization. We describe a new method for estimating elastic moduli of rocks in-situ by simulating the effect of mud-filtrate invasion on resistivity and acoustic logs. Simulations of mud-filtrate invasion account for the dynamic process of fluid displacement and mixing between mud-filtrate and hydrocarbons. The calculated spatial distributions of electrical resistivity are matched against resistivity logs by adjusting the underlying petrophysical properties. We then perform Biot-Gassmann fluid substitution on the twodimensional spatial distributions of fluid saturation with initial estimates of dry-bulk (kdry) modulus and shear rigidity ([Greek small letter mu]dry) and a constraint of Poisson's ratio (ν) typical of the formation. This process generates two-dimensional spatial distributions of compressional and shear-wave velocities, and density. Subsequently, sonic waveforms are simulated to calculate shear-wave slowness. Initial estimates of the dry-bulk modulus are progressively adjusted using a modified Gregory-Pickett (1984) solution to Biot's (1956) equation to estimate a shear rigidity that converges to the log value of shear-wave slowness. The constraint on Poisson's ratio is then removed and a refined estimate of the dry-bulk modulus is obtained by both simulating the acoustic log (monopole) and matching the log-derived compressional-wave slowness. This technique leads to reliable estimates of dry-bulk moduli and shear rigidity that compare well to laboratory core measurements. The resulting dry-rock elastic properties can be used to calculate seismic compressional-wave and shear-wave velocities devoid of mud-filtrate invasion effects for further seismic-driven reservoir characterization studies. | en_US |
dc.description.department | Petroleum and Geosystems Engineering | en_US |
dc.format.medium | electronic | en_US |
dc.identifier | doi:10.15781/T2891257G | |
dc.identifier.uri | http://hdl.handle.net/2152/60374 | |
dc.language.iso | eng | en_US |
dc.relation.ispartof | UT Electronic Theses and Dissertations | en_US |
dc.rights | Copyright © is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. | en_US |
dc.rights.restriction | Restricted | en_US |
dc.subject | Hydrocarbon reservoirs | en_US |
dc.subject | Seismic response | en_US |
dc.subject | Mud-filtrate invasion | en_US |
dc.title | Estimation of dry-rock elastic moduli based on the simulation of mud-filtrate invasion effects on borehole acoustic logs | en_US |
dc.type | Thesis | en_US |
dc.type.genre | Thesis | en_US |
thesis.degree.department | Petroleum and Geosystems Engineering | en_US |
thesis.degree.discipline | Petroleum Engineering | en_US |
thesis.degree.grantor | University of Texas at Austin | en_US |
thesis.degree.level | Masters | en_US |
thesis.degree.name | Master of Science | en_US |
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