Transport and dielectric properties of thin fullerene (C₆₀) films

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 229-251).by Boris Pevzner.M.S

Estimation of Scattering Attenuation from Zero-offset VSP Data: CO2CRC Otway Project Case Study

Seismic attenuation consists of anelastic absorption and scattering loss. Due to the dominance of stratification, the scattering attenuation in the sedimentary crust is dominated by 1-D scattering. In this study we applied an integrated workflow for estimation of attenuation from ZVSP and log data to a comprehensive dataset acquired at Otway basin. Both 1D reflectivity modeling and application of generalized O’Doherty-Anstey theory to the Otway log data shows that the 1-D scattering component of attenuation gives Q of over 200. At the same time, average Q estimated from field VSP data value is close to 60. Hence we conclude that scattering plays a relatively minor role in the study area. Further research is required to understand whether this conclusion holds in other areas. In particular, scattering attenuation might be larger in environments with larger variability of elastic properties between layers, such as in areas with laminated coal layers

3C laboratory ultrasound: A new method for measuring elastic anisotropy of rocks

We propose a new method for measuring velocities and polarizations of the compressional and shear waves. The method consists of measuring time dependent displacement of a particular point on the sample surface in three independent directions by a laser Doppler interferometer. The high accuracy of these measurements makes the determination of the polarization straightforward, and thus the identification the type of the waves unambiguous. These measurements can be used to estimate the stiffness tensor of anisotropic rock samples

Elastic anisotropy estimation from laboratory measurements of velocity and polarization of quasi-P-waves using laser interferometry

A new method for conducting laboratory measurements of the velocities and polarizations of compressional and shear waves in rock samples uses a laser Doppler interferometer (LDI). LDI can measure the particle velocity of a small (0.03mm2) element of the surface of the sample along the direction of the laser beam. By measuring the particle velocity of the same surface element in three linearly independent directions and then transforming those velocities to Cartesian coordinates, three orthogonal components of the particle-velocity vector are obtained. Thus, LDI can be used as a localized three-component(3C) receiver of ultrasonic waves, and, together with a piezoelectric transducer as a source, it can simulate a 3C seismic experiment in the laboratory. Performing such 3C measurements at various locations on the surface of the sample produces a 3C seismogram, which can be used to separate the P-wave and two S-waves and to find the polarizations and traveltimes of those waves. Then, the elasticity tensor of the medium can be obtained by minimizing the misfit between measured and predicted polarizations and traveltimes. Computation of the polarizations and traveltimes of body waves inside a sample with a given elasticity tensor is based on the Christoffel equation.The predicted polarizations on the surface then are obtained using the anisotropic Zoeppritz equations. The type of velocity measured (phase or group velocity) depends on the acquisition geometry and the material properties. This is taken into account in the inversion procedure. A “walkaway” laboratory experiment demonstrates the high accuracy of this method

Application of diffracted waves analysis to edge detection on 3D and 4D seismic data

Over the past several decades diffracted wave analysis was applied to such problems as detection of small objects on seismic and GPR data, enhanced fault imaging, detection of edges of the geological bodies. Recently we showed using 2D mathematical modelling the potential of diffracted wave analysis for detection of the CO2 leakage. In this paper we illustrate application of several diffracted waves imaging techniques based on the phase reversal phenomena for to detection of edges of the objects on 2D data and generalize the approach for 3D acquisition geometry. The proposed technique was tested on physical modelling data and 4D seismic data acquired as a part of CO2CRC Otway project conducted by the Cooperative Research Centre for Greenhouse Gases Technologies (CO2CRC)

Seismic anisotropy estimation from VSP data: CO2CRC Otway project case study

We present and compare results of several methods of seismic anisotropy estimation from borehole seismic data obtained for Otway CO2 geosequestration project, Australia. The presented methods include multicomponent velocity analysis for estimation of shear wave splitting from zero-offset VSP data, P-wave anisotropy from 3D VSP transit times, and from slownesses and polarizations in 3D 3C VSP data. The results of the methods are consistent with each other and also with the cross-dipole sonic log data

Feasibility of time-lapse seismic methodology for monitoring the injection of small quantities of CO2 into a saline formation, CO2CRC Otway Project

A key objective of Stage 2 of the CO2CRC Otway Project is to explore the ability of geophysical methods to detect and monitor injection of greenhouse gas into a saline formation. For this purpose, injection of some 10,000 30,000 tonnes of CO2-rich mixture into the Paaratte formation, a saline aquifer located at a depth of about 1,400 m, is planned. Before such an injection experiment is undertaken, we assess the feasibility of geophysical monitoring using computer modelling. To examine the detectability of the plume we need to estimate the time-lapse signal and time- lapse noise. The time lapse signal is modelled using flow simulations, fluid substitution and seismic forward modelling. In order to assess the applicability of time-lapse seismic to monitor the injection, the predicted signal is compared to the time-lapse noise level from the recent 4D seismic survey acquired at the Otway site in 2009-2010. The methodology is applied to two alternative reservoir intervals located at a depth of 1392-1399 m and 1445-1465 m below the sea level, respectively. These intervals are considered to be the two possible options for the injection. The results show that injection into the lower interval will produce a plume of a larger thickness and smaller lateral extent, and a seismic response that is more likely to be detectable. The developed feasibility assessment workflow, and the results of its application to the Otway site, can be used to assess the ability of seismic methods to detect and monitor greenhouse gas leakage in other CCS projects