Publications

2016
V. Puzyrev and Torres-Verdín, C., “Inversion-based interpretation of 3D borehole directional resistivity measurements acquired in high-angle and horizontal wells (Expanded Abstract),” Society of Exploration Geophysicists (SEG) 86th Ann. Internat. Mtg. Dallas, TX, October 16-21, 2016.
S. Huang and Torres-Verdín, C., “Inversion-based interpretation of borehole sonic measurements using semi-analytical spatial sensitivity functions,” Geophysics, vol. 81, no. 2, pp. D111-D124, 2016.
S. Huang and Torres-Verdín, C., “Inversion-based interpretation of borehole sonic measurements using semi-analytical spatial sensitivity functions,” Geophysics, vol. 81, no. 2, pp. D111-D124, 2016.
S. Huang and Torres-Verdín, C., “Inversion-based interpretation of borehole sonic measurements using semi-analytical spatial sensitivity functions,” Geophysics, vol. 81, no. 2, pp. D111-D124, 2016.
O. Ajayi, Torres-Verdín, C., and Preeg, W. E., “Inversion-based interpretation of logging-while-drilling gamma-ray spectroscopy measurements.,” Geophysics, vol. 81, no. 1, pp. D9-D34, 2016.
O. Ajayi, Torres-Verdín, C., and Preeg, W. E., “Inversion-based interpretation of logging-while-drilling gamma-ray spectroscopy measurements,” Geophysics, vol. 81, no. 1, pp. D9-D34, 2016.
M. J. Ramos, Espinoza, D. N., Torres-Verdín, C., Shovkun, I., and Grover, T., “Laboratory characterization and detection of fractures through combined ultrasonic and triaxial-stress testing (Extended Abstract).,” American Rock Mechanics Association (ARMA) 50th US Rock Mechanics/Geomechanics Symposium. Houston, Texas, June 26-29, 2016.
M. J. Ramos, Espinoza, D. N., Torres-Verdín, C., Shovkun, I., and Grover, T., “Laboratory characterization and detection of fractures through combined ultrasonic and triaxial-stress testing (Extended Abstract),” American Rock Mechanics Association (ARMA) 50th US Rock Mechanics/Geomechanics Symposium. Houston, Texas, June 26-29, 2016.
L. Zhang, Xiao, P., Shi, L., Henkelman, G., Goodenough, J. B., and Zhou, J., “Localized Mg-vacancy states in the thermoelectric material Mg2−δSi0.4Sn0.6,” Journal of Applied Physics, vol. 119, pp. 085104, 2016. Publisher's Version
E. E. Ureña-Benavides, Lin, E. L., Foster, E. L., Xue, Z., Ortiz, M., Fei, Y., Larsen, E. S., Kmetz II, A. A., Lyon, B. A., and Bielawski, C. W., “Low Adsorption of Magnetite Nanoparticles with Uniform Polyelectrolyte Coatings in Concentrated Brine on Model Silica and Sandstone,” Industrial & Engineering Chemistry Research, 2016. Publisher's VersionAbstract
In subsurface imaging and oil recovery where temperatures and salinities are high, it is challenging to design polymer-coated nanoparticles with low retention (high mobility) in porous rock. Herein, the grafting of poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylic acid) (poly(AMPS-co-AA)) on magnetic iron oxide nanoparticles was sufficiently uniform to achieve low adsorption on model colloidal silica and crushed Berea sandstone in highly concentrated API brine (8% NaCl and 2% CaCl2 by weight). The polymer shell was grafted via amide bonds to an aminosilica layer, which was grown on silica-coated magnetite nanoparticles. The particles were found to be stable against aggregation in American Petroleum Institute (API) brine at 90 °C for 24 h. For IO nanoparticles with ∼23% polymer content, Langmuir adsorption capacities on colloidal silica and crushed Berea Sandstone in batch experiments were extremely low at only 0.07 and 0.09 mg of IO/m2, respectively. Furthermore, upon injection of a 2.5 mg/mL IO suspension in API brine in a column packed with crushed Berea sandstone, the dynamic adsorption of IO nanoparticles was only 0.05 ± 0.01 mg/m2, which is consistent with the batch experiment results. The uniformity and high concentration of solvated poly(AMPS-co-AA) chains on the IO surfaces provided electrosteric stabilization of the nanoparticle dispersions and also weakened the interactions of the nanoparticles with negatively charged silica and sandstone surfaces despite the very large salinities.
Z. Wang, Xu, X., Fan, D., Wang, Y., and Chen, R., “Low-loss Subwavelength Grating Waveguide Bends Based on Index Engineering,” in CLEO: Science and Innovations 2016, San Jose, California, United States, 2016. Publisher's VersionAbstract
We report the design, simulation and experimental demonstration of low loss subwavelength grating waveguide (SWG) bends. With trapezoidal shape silicon pillars, the average insertion loss of a 5μm SWG waveguide bend is reduced drastically from 5.43dB to 1.10dB per 90°bend for quasi-TE polarization.
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L. A. Jauregui, Pettes, M. T., Rokhinson, L. P., Shi, L., and Chen, Y. P., “Magnetic field-induced helical mode and topological transitions in a topological insulator nanoribbon,” Nature Nanotechnology, vol. 11, pp. 345–351, 2016. Publisher's VersionAbstract
The spin-helical Dirac fermion topological surface states in a topological insulator nanowire or nanoribbon promise novel topological devices and exotic physics such as Majorana fermions. Here, we report local and non-local transport measurements in Bi2Te3 topological insulator nanoribbons that exhibit quasi-ballistic transport over ∼2 μm. The conductance versus axial magnetic flux Φ exhibits Aharonov–Bohm oscillations with maxima occurring alternately at half-integer or integer flux quanta (Φ0 = h/e, where h is Planck's constant and e is the electron charge) depending periodically on the gate-tuned Fermi wavevector (kF) with period 2π/C (where C is the nanoribbon circumference). The conductance versus gate voltage also exhibits kF-periodic oscillations, anti-correlated between Φ = 0 and Φ0/2. These oscillations enable us to probe the Bi2Te3 band structure, and are consistent with the circumferentially quantized topological surface states forming a series of one-dimensional subbands, which undergo periodic magnetic field-induced topological transitions with the disappearance/appearance of the gapless Dirac point with a one-dimensional spin helical mode.
K. An, Olsson, K. S., Weathers, A., Sullivan, S., Chen, X., Li, X., Marshall, L. G., Ma, X., Klimovich, N., Zhou, J., Shi, L., and Li, X., “Magnons and Phonons Optically Driven out of Local Equilibrium in a Magnetic Insulator,” Phys. Rev. Lett., vol. 117, pp. 107202, 2016. Publisher's Version
Q. Cui, Ren, P., and Meuwly, M., Many-Body Effects and Electrostatics in Biomolecules. Pan Stanford, 2016. Publisher's Version
K. Emmert, Kopel, R., Sulzer, J., Brühl, A. B., Berman, B. D., Linden, D. E. J., Horovitz, S. G., Breimhorst, M., Caria, A., and Frank, S., “Meta-analysis of real-time fMRI neurofeedback studies using individual participant data: How is brain regulation mediated?,” NeuroImage, vol. 124, pp. 806-812, 2016.
M. Nole, Daigle, H., Milliken, K. L., and Prodanović, M., “A method for estimating microporosity of fine‐grained sediments and sedimentary rocks via scanning electron microscope image analysis,” Sedimentology, vol. 63, no. 6, pp. 1507-1521, 2016.
L. Cui, Ma, K., Puerto, M., Abdala, A. A., Tanakov, I., Lu, L. J., Chen, Y., Elhag, A., Johnston, K. P., and Biswal, S. L., “Mobility of ethomeen C12 and carbon dioxide (CO 2) foam at high temperature/high salinity and in carbonate cores,” SPE Journal, 2016. Publisher's VersionAbstract
The low viscosity and density of carbon dioxide (CO2) usually result in the poor sweep efficiency in CO2-flooding processes, especially in heterogeneous formations. Foam is a promising method to control the mobility and thus reduce the CO2 bypass because of the gravity override and heterogeneity of formations. A switchable surfactant, Ethomeen C12, has been reported as an effective CO2-foaming agent in a sandpack with low adsorption on pure-carbonate minerals. Here, the low mobility of Ethomeen C12/CO2 foam at high temperature (120°C), high pressure (3,400 psi), and high salinity [22 wt% of total dissolved solids (TDS)] was demonstrated in Silurian dolomite cores and in a wide range of foam qualities. The influence of various parameters, including aqueous solubility, thermal and chemical stability, flow rate, foam quality, salinity, temperature, and minimum-pressure gradient (MPG), on CO2 foam was discussed. A local-equilibrium foam model, the dry-out foam model, was used to fit the experimental data for reservoir simulation
A. Qajar, Xue, Z., Worthen, A. J., Johnston, K. P., Huh, C., Bryant, S. L., and Prodanović, M., “Modeling fracture propagation and cleanup for dry nanoparticle-stabilized-foam fracturing fluids,” Journal of Petroleum Science and Engineering, vol. 146, pp. 210-221, 2016. Publisher's VersionAbstract
Nanoparticle (NP)-stabilized foams can be generated at extreme water-deficient conditions (with quality as high as 95–99%) and yet with apparent viscosities >100 cP. This makes them greatly appealing for hydraulic fracturing applications, where minimal water consumption and leak-off to the reservoir are desired. Initial assessment of propensities of these novel fluids for fracturing applications requires field scale simulations. However, conventional fracturing models are difficult to employ because they do not consider true foam hydrodynamics. We have developed a mathematical model to simulate the transport of NP-stabilized foams for hydraulic fracturing. The model combines fluid transport in reservoir matrix and fracture with rock mechanics equations and thus allows for considering the effects of foam on fracture dynamics. Gas and water flow with mechanistic accounting of foam generation and coalescence are simulated using population balance models. Transport of nanoparticles through porous media was simulated using single site filtration model. The equations are discretized using finite-difference scheme. Settari’s approach is used to embed fracture’s moving boundary with the matrix to accordingly update transmissibility. Model’s capabilities are verified with examples on fracture growth and fracture clean up processes to illustrate the benefits of using the NP-stabilized high quality foams. Fracture propagation was simulated for water, a conventional viscous fracpad and NP-stabilized foams of different qualities and textures. The simulations confirmed that larger foam viscosity generated wider fractures with smaller fracture half-length. In addition, fracture cleanup simulations show that fracturing fluid cleanup for foam based fracturing fluids could take the order of 10 days as opposed to that of viscous fracpad which could take up to 1000 days; demonstrating the advantage of using dry foams
A. Karpatne and Sirohi, J., “Modeling Internal Flow Through a Rotating Duct Using Quasi 1-D Euler Equations,” AIAA Journal, pp. 1–13, 2016.
B. Ghanbarian, Sahimi, M., and Daigle, H., “Modeling relative permeability of water in soil: Application of effective‐medium approximation and percolation theory,” Water Resources Research, vol. 52, no. 7, pp. 5025-5040, 2016.

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