D. Pardo and Torres-Verdín, C., “Sensitivity analysis for the appraisal of hydrofractures in horizontal wells with borehole resistivity measurements,” Geophysics, vol. 78, pp. D209-D222, 2013.PDF icon PDF
M. J. Nam, Pardo, D., and Torres-Verdín, C., “Simulation of borehole-eccentered tri-axial induction measurements using a Fourier hp finite-element method,” Geophysics, vol. 78, pp. D41-D52, 2013.PDF icon PDF
P. Matuszyk and Torres-Verdín, C.,Back-propagating modes in elastic logging-while-drilling collars and their effect on PML stability,” Computers and Mathematics with Applications, vol. 66, pp. 2335-2343, 2013.Abstract
The Perfectly Matched Layer (PML) approach is widely used to implement the absorbing boundary conditions for coupled multi-physics wave propagation problems. However, it has been recognized that the solution in the PML absorbing layer can become unstable in the presence of back-propagating modes. This paper analyzes the spectral location of those modes excited by monopole acoustic sources in logging-while-drilling cylindrical tools. To recover the stability of the solution for such a class of problems involving the modeling of elastic cylindrical waveguides, we propose the implementation of artificial attenuation in the waveguide to dampen undesirable modes, thereby making their amplitude negligible in the PML absorbing layer due to the limited numerical accuracy and round-off errors.
PDF icon PDF
A. Revil, Woodruff, W. F., Torres-Verdín, C., and Prasad, M., “Complex conductivity tensor of anisotropic hydrocarbon-bearing shales and mudrocks,” Geophysics, vol. 78, pp. D403-D418, 2013.Abstract
A model was recently 26 introduced to describe the complex electrical conductivity and high frequency dielectric constant of isotropic clayey porous materials. That approach is generalized here to the case of anisotropic and tight hydrocarbon-bearing shales and mudrocks by introducing tensorial versions of both formation factor and tortuosity. It is shown that in-phase and quadrature conductivity tensors have common eigenvectors, but that the eigenvectors of the dielectric tensor may be different due to influence of the solid phase at high requencies. In-phase and quadrature contributions to complex electrical conductivity depend on saturation, salinity, porosity, temperature, and cation exchange capacity (alternatively, specific surface area) of the porous material. Kerogen is likely to have a negligible contribution to the cation exchange capacity of the material because all exchangeable sites in the functional groups of organic matter may have been polymerized during diagenesis. An anisotropic experiment is performed to validate some of the properties described by the proposed model, especially to verify that the electrical anisotropy factor is the same for both in-phase and quadrature conductivities. We use two samples from the Bakken formation. Experimental data confirm the validity of the model. It is also found that the range of values for cation exchange capacity determined when implementing the new model with experimental data agree with the known range of cation exchange capacity for the Bakken shale. Measurements indicate that the bulk-space tortuosity in the direction normal to bedding plane can be higher than 100.
PDF icon PDF
C. Xu and Torres-Verdín, C., “Interpretation of hydraulic rock types with resistivity logs in Tertiary deepwater turbidite reservoirs,” Pore-scale modeling verified with field observations in the Gulf of Mexico, USA: Interpretation, vol. 1, pp. T177–T185, 2013.PDF icon PDF
O. Ijasan, Torres-Verdín, C., and Preeg, W. E., “Interpretation of porosity and fluid constituents from well logs using an interactive neutron-density matrix scale,” Interpretation, vol. 1, pp. T143-T155, 2013.PDF icon PDF
O. Ijasan, Torres-Verdín, C., and Preeg, W. E., “Inversion-based petrophysical interpretation of logging-while-rilling nuclear and resistivity measurements,” Geophysics, vol. 78, pp. D473-D489, 2013.PDF icon PDF
C. Xu and Torres-Verdín, C., “Quantifying fluid distribution and phase connectivity with a simple 3D cubic pore network model constrained by NMR and MICP data,” Computers and Geosciences, vol. 61, pp. 94-103, 2013.PDF icon PDF
V. Shabro, Torres-Verdín, C., Javadpour, F., and Sepehrnoori, K., “Finite-difference approximation for fluid-flow simulation and calculation of permeability in porous media,” Transport in Porous Media, vol. 94, pp. 775-793, 2012.PDF icon PDF
Z. Heidari, Torres-Verdín, C., and Preeg, W. E., “Improved estimation of fluid and mineral volumetric concentrations from well logs in thinly bedded and invaded formations,” Geophysics, vol. 77, pp. WA79-WA98, 2012.PDF icon PDF
A. Mendoza, Ijasan, O., Torres-Verdín, C., Preeg, B., Rasmus, J., Radtke, R. J., and Stockhausen, E., “Inversion-based method for interpretation of logging-while-drilling density measurements acquired in high-angle and horizontal wells,” Geophysics, vol. 77, pp. D113-D127, 2012.PDF icon PDF
P. Matuszyk, Demkowicz, L., and Torres-Verdín, C., “Solution of coupled acoustic-elastic wave propagation problems with anelastic attenuation using automatic hp-adaptivity,” Computer Methods in Applied Mechanics and Engineering (CMAME), vol. 200, pp. 299-313, 2012.PDF icon PDF
Z. Heidari and Torres-Verdín, C., “Estimation of dynamic petrophysical properties of water-bearing sands invaded with oil-base mud from the interpretation of multiple borehole geophysical measurements,” Geophysics, vol. 77, pp. D209-D227, 2012.PDF icon PDF
R. Angeles, Torres-Verdín, C., Sepehrnoori, K., and Elshahawi, H., “History matching of multiphase-flow formation-tester measurements acquired with focused-sampling probes in deviated wells,” Petrophysics, vol. 52, pp. 14-31, 2011.PDF icon PDF
F. O. Alpak, Habashy, T. M., Abubakar, A., Torres-Verdín, C., and Sepehrnoori, K., “A multiplicative regularized Gauss-Newton algorithm and its application to the joint inversion of induction logging and near-borehole pressure measurements,” Progress in Electromagnetics Research B, vol. 29, pp. 105–138, 2011.PDF icon PDF
D. Pardo, Nam, M. J., Torres-Verdín, C., Hoversten, M., and Garay, I., “Simulation of marine controlled source electromagnetic measurements using a parallel Fourier hp-finite element method,” Computational Geosciences, vol. 15, pp. 53-67, 2011.PDF icon PDF
Z. Heidari, Torres-Verdín, C., Mendoza, A., and Wang, G. L., “Assessment of residual hydrocarbon saturation with the combined quantitative interpretation of resistivity and nuclear logs,” Petrophysics, vol. 52, pp. 217-237, 2011.PDF icon PDF
J. M. Salazar, Torres-Verdín, C., and G. L. Wang,Effects of surfactant-emulsified oil-based mud on borehole resistivity measurements,” SPE Journal, vol. 16, pp. 608-624, 2011.PDF icon PDF
J. Mimoun, Torres-Verdín, C., and Preeg, W. E., “Quantitative interpretation of pulsed neutron capture logs, Part II: inversion of measurements in thinly-bedded formations,” Geophysics, vol. 76, pp. E95-E103, 2011.PDF icon PDF
J. Mimoun, Torres-Verdín, C., and Preeg, W. E., “Quantitative interpretation of pulsed neutron capture logs, Part I: fast numerical simulation,” Geophysics, vol. 76, pp. E81-E93, 2011.PDF icon PDF