Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1988. / Bibliography: v.2, leaves 382-403. / by Donald Degarmo Hickmott. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1996. / Includes bibliographical references (p. 214-217). / by David Paul Hawkins. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1988. / 2 folded maps in pocket. Vita. / Includes bibliographical references (leaves 158-167). / by Mary Syndonia Hubbard. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1985. / Bibliography: leaves 151-154. / by Brian R. Bennett. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2008. / Includes bibliographical references (p. 287-299). / In this thesis we address the problem of determining in situ stress and fracture properties in reservoirs using borehole logs and surface seismic reflection data. The dissertation covers four subtopics. The first is the determination of horizontal stress magnitudes from measurements in a borehole. Two types of data used are stress-induced rock failures in the borehole, known as "breakouts," and the dispersions of polarized flexural waves which propagate along the borehole. Traditionally these data are analyzed to derive stress orientations but not magnitudes. To determine the magnitude of stresses directly from breakouts, we use an iterative elastic modeling of stresses around the borehole and Mohr-Coulomb failure criterion to match the borehole deformation. As a second method we use dispersion curves of the two polarized flexural waves and their crossover points. These methods are applied to data from a well in northeastern Venezuela. The combination of these two techniques provides a complete profile of stress as a function of depth since the first method is applied at the breakout depths and the second is applied everywhere else in the borehole. Both borehole methods agree in the estimation of stress orientation and magnitude. The maximum horizontal stress is in the NNW-SSE direction, in agreement with a regional stress model calculated from the relative motions of the Caribbean and South America plates. The magnitudes of principal stresses are on average, SHmax 1.1Sv (Sv: vertical stress) and Shmin 0.9Sv (Shmin: minimum horizontal stress). This suggests strike-slip faulting, consistent with earthquake mechanisms in the region. The in situ stresses play an important role on determining the properties of fractured formation. The azimuth of SHmax determines the preferred orientation of open fractures. Surface seismic reflection data provide the means for detecting the fractures. / (cont.) The second contribution of this thesis is developing a method to detect discrete fractures, and to determine their orientation and average spacing. We developed a novel and practical technique, called the F-K method, based on the frequency wavenumber (f-k) domain analysis of seismic coda. The fractured medium targeted in this study is a network of rather regularly spaced, parallel, sub-vertical fractures, with dimensions similar to seismic wavelength. The seismic response of a fractured medium is studied by finite difference numerical models for a variety of situations where orientation, spacing, height, and fracture compliance are varied. In the direction normal to fractures, scattered waves propagate with slower apparent velocities than waves propagating along the fractures. The orientation of fractures is well constrained from the azimuthal dependence of scattering. The spectral characteristics (frequency, wavenumber and amplitude) of the backscattered waves are related to fracture properties like spacing, compliance, and height. The dominant wavenumber is very sensitive to fracture spacing. We use the F-K method to analyze a data set from the Lynx Field in Canada. Characterization of fracture properties in this field is important for development plans to maximize the gas production. In the field data, the acquisition geometry results in irregular fold, with under sampling of certain azimuths and offsets. We address the acquisition footprint issue by controlling the azimuth binning of the data and neglecting the low/irregular fold gathers in the fracture analysis. We also apply the Scattering Index (SI) method (Willis et al., 2006) to the same data from the Lynx Field. The SI method is a robust method to detect fractures and to provide fracture orientations using multi-azimuth/multi-offset pre-stack data. In the realm of existing 3D seismic surveys, data with such acquisition characteristics are few. / (cont) The fourth contribution of this thesis is therefore the conception of a post-stack version of the SI method that extends the scope of this method to practically every 3D seismic surface data set. In this version, a scattering index is computed for a fully stacked trace per CMP gather. As long as the bin contains traces parallel to the fracture strike, the stacking process of all azimuths and offsets preserves the reverberating character introduced by the fractures. The post-stack SI at a fractured location has a large value in comparison to a non-fractured location. The variations of post-stack SI values across the field reveal the distribution of highly fractured areas. Fracture strike cannot be determined in this case because it does not include the azimuthal behavior of the scattering. However, the results from the post-stack SI are helpful to identify areas of interest to focus the more specialized scattering analysis methods. We apply the F-K and SI methods to the Lynx Field seismic data and compare the results. Since spatial resolution of the two methods are different we upscale the SI maps to match the resolution of the F-K method. The combined analysis of the Lynx Field indicates that the preferred fracture orientation is N400E, which agrees with the regional stress field. The distribution of highly fractured regions appears to be associated to the geological features, such as folds and faults. The average fracture spacing, obtained by the F-K method shows that, in the Lynx Field, fracture spacing decreases in the west side of the field where the structural dips are higher. / by Samantha Grandi-Karam. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1984. / Bibliography: leaves 78-86. / by Brian Daniel Taras. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1997. / Includes bibliographical references (leaves 74-79). / by Asantha Roshan Cooray. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1985. / Microfiche copy available in Archives and Science. / Bibliography: p. 160-165. / by Melinda M. Hall. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2001. / Includes bibliographical references. / Two-dimensional resistivity inversion employing regularization enforces a constraint of smoothness that minimizes error and avoids unrealistically complex solutions to the inverse problem. The insensitivity of surface array data to deeper targets typically presents an under-determined problem for solution by the inversion algorithm, and the smoothing function within the algorithm tends to "smear" tomographic imagery. Together, the physical challenges of electrical resistivity as a geophysical method and the numerical challenges inherent in solving the inverse problem introduce errors in the accuracy of 2D resistivity imagery. It is important to know what surface array geometry will provide data that yields the best results from the inversion. Testing this inversion algorithm on data from several array geometries provides the opportunity to determine the comparative performance of each survey method. By introducing two types of resistive anomalies and varying their location within a synthetic homogeneous half-space, it is possible to generate synthetic data with a forward model algorithm. The data from each array geometry is then inverted in order to illustrate the accuracy and resolution response of the inversion algorithm. The inversion images are converted into binary images after defining a critical resistivity that describes the contrast between background resistivity and target resistivity. The binary images are used as interpretive tools that allow the user to overcome the "smearing" introduced by the inversion. Because of its consistent performance from the margins to the center of an array, a left-right sweep geometry combined with a pseudo section geometry appears to be the best choice for a surface array when there is no knowledge of the subsurface structure or resistivity distribution. The critical resistivity and the area of the anomaly are used to describe the performance of the inversion. When taken as functions of increasing depth, the critical resistivity decreases and the area of anomaly increases, providing a respective correlation with the current density and the degree of smoothness. Initial results by forming a product of critical resistivity and area suggest that it is possible to approximate the product from the original forward model, but further testing is warranted to provide more conclusive results. / by Jeffrey Z. Snyder. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2006. / Includes bibliographical references (p. 47-48). / Using a standardized fault geometry based on the Community Block Model, we create two analytic block models of the southern California fault system. We constrain one model with only geodetic data. In the other, we assign a priori slip rates to the San Andreas, Garlock, Helendale, Newport-Inglewood, Owens Valley, Sierra Madre, and Chino faults to create a joint geologic and geodetic model, using the a priori slip rates to refine the results in areas with limited geodetic data. Our results for the San Andreas fault are consistent with geologic slip rates in the north and south, but across the Big Bend area we find its slip rates to be slower than geologic rates. Our geodetic model shows right lateral slip rates of 19.8 + 1.3 mm/yr in the Mojave area and 17.3 ± 1.6 mm/yr near the Imperial fault; the San Gorgonio Pass area displays a left lateral slip rate of 1.8 + 1.7 mm/yr. Our joint geologic and geodetic model results include right lateral slip rates of 18.6 + 1.2 mm/yr in the Mojave area, 22.1 ± 1.6 mm/yr near the Imperial fault, and 9.5 1.4 mm/yr in the San Gorgonio Pass area. Both models show high values (10-13 1 mm/yr) of right lateral slip to the east of the Blackwater fault along the Goldstone, Calico, and Hidalgo faults. We show that substantially different block geometries in the Mojave can produce statistically similar model results due to sparse geodetic data. / by Lori A. Eich. / S.M.