<p> The first part of my thesis is mainly focused on the effect of grain size distribution on compaction localization in porous sandstone. To identify the microstructural parameters that influence compaction band formation, I conducted a systematic study of mechanical deformation, failure mode and microstructural evolution in Bleurswiller and Boise sandstones, of similar porosity (&sim;25%) and mineralogy but different sorting. Discrete compaction bands were observed to develop over a wide range of pressure in the Bleurswiller sandstone that has a relatively uniform grain size distribution. In contrast, compaction localization was not observed in the poorly sorted Boise sandstone. My results demonstrate that grain size distribution exerts important influence on compaction band development, in agreement with recently published data from Valley of Fire and Buckskin Gulch, as well as numerical studies. </p><p> The second part aimed to improve current knowledge on inelastic behavior, failure mode and brittle-ductile transition in another sedimentary rock, porous carbonates. A micritic Tavel (porosity of &sim;13%) and an allochemical Indiana (&sim;18%) limestones were deformed under compaction in wet and dry conditions. At lower confining pressures, shear localization occurred in brittle faulting regime. Through transitional regime, the deformation switched to cataclastic flow regime at higher confining pressure. Specifically in the cataclastic regime, the (dry and wet) Tavel and dry Indiana failed by distributed cataclastic flow, while in contrast, wet Indiana failed as compaction localization. My results demonstrate that different failure modes and mechanical behaviors under different deformation regimes and water saturation are fundamental prior to any geophysical application in porous carbonates. </p><p> The third part aimed to focus on investigating compaction on quartz aggregate starting at low (MPa) using X-ray diffraction. We report the diffraction peak evolution of quartz with increasing pressures. Through evaluating the unit cell lattice parameters and the volume of the quartz sample, macroscopic stress and strain were resolved. Moreover, we observed quartz peak broadened asymmetrically at low pressure, such extent is more prominent in axial than in radial direction. Our evaluation on peak [101] (highest intensity among peaks) demonstrated that full width at half maximum can be a good proxy for microscopic stress distribution. We observed deviations in the pressure-volume curves at P = &sim;0.4 GPa and speculated that it was the point of which onset of grain crushing and pore collapse occur in quartz. This is on the same order of which onset of grain crushing (commonly known as P*) is observed in sandstones in the rock mechanics literature. This demonstrated that there is potential in estimating grain crushing and pore collapse pressure with our technique.</p>

<p> The abstract is not available from PDF copy and paste.</p>

<p> Among the most important properties controlling the production from conventional oil and gas reservoirs is the distribution of porosity and permeability within the producing geologic formation. The geometry of the pore space within these reservoirs, and the permeability associated with this pore space geometry, impacts not only where production can occur and at what flow rates but can also have significant influence on many other rock properties. Zones of high matrix porosity can result in an isotropic response for certain reservoir properties whereas aligned porosity/permeability, such as open, natural fracture trends, have been shown to result in reservoirs being anisotropic in many properties.</p><p> The ability to identify zones within a subsurface reservoir where porosity/permeability is significantly higher and to characterize them according to their geometries would be of great significance when planning where new boreholes, particularly horizontal boreholes, should be drilled. The detection and characterization of these high porosity/permeability zones using their isotropic and anisotropic responses may be possible through the analysis of azimuthal (also referred to as azimuth-limited) 3D seismic volumes.</p><p> During this study the porosity/permeability systems of a carbonate, pinnacle reef within the northern Michigan Basin undergoing enhanced oil recovery were investigated using selected seismic attributes extracted from azimuthal 3D seismic volumes. Based on the response of these seismic attributes an interpretation of the geometry of the porosity/permeability system within the reef was made. This interpretation was supported by well data that had been obtained during the primary production phase of the field. Additionally, 4D seismic data, obtained as part of the CO₂ based EOR project, supported reservoir simulation results that were based on the porosity/permeability interpretation.</p>

<p> The history of late Miocene (Proto-Gulf) deformation on the Sonoran margin of the Gulf of California is key to understanding how Baja California was captured by the Pacific plate and how strain was partitioned during the Proto-Gulf period (12.5-6 Ma). The Sierra el Aguaje and Sierra Tinajas del Carmen are located in southwestern coastal Sonora, Mexico, and represent the eastern rifted margin of the central Gulf of California. The ranges are composed of volcanic units and their corresponding volcaniclastic units which are the result of persistent magmatic activity between 20 and 8.8 Ma, including three packages of basalt and andesite that make excellent paleomagnetic recorders. Based on cross cutting relations and geochronologic data for pre-, syn-, and post-tectonic volcanic units, most of the faulting and tilting in the Sierra El Aguaje is bracketed between 11.9 and 9.0 Ma, thus falling entirely within Proto-Gulf time. </p><p> A paleomagnetic investigation into possible vertical axis rotations in the Sierra el Aguaje has uncovered evidence of clockwise rotations between ~13&ordm; and ~105&ordm; with possible translations. These results are consistent with existing field relations, which suggest the presence of large (>45&deg;) vertical axis rotations in this region. This evidence includes: a) abrupt changes in the strike of tilted strata in different parts of the range, including large domains characterized by E-W strikes b) ubiquitous NE-SW striking faults with left lateral-normal oblique slip, that terminate against major NW-trending right lateral faults, and c) obliquity between the general strike of tilted strata and the strike of faults. These rotations occurred after 12 Ma and largely prior to 9 Ma, thus falling into the Proto-Gulf period. Such large-scale rotations lend credence to the theory that the area inboard of Baja California was experiencing transtension during the Proto-Gulf period, rather than the pure extension that would be the result of strain partitioning between Sonora and the Tosco-Abreojos fault offshore Baja California.</p>

<p> The transition between the two distinct structural regimes of the Walker Lane and the Basin and Range allows for complex transtensional fault interactions. The Carson Sink is the surface expression of the interaction of shear and extensional strains that cause both crustal extension and block rotation. This study investigates this tectonic shift at the Soda Lake geothermal field by comparing the direction and rate of deformation from both regional GPS and a 34 sq km 3D seismic survey. The GPS stations in the region estimate the strain field by comparing tensor solutions that show changing direction and magnitude of strain across the Carson Sink. Using stations surrounding the Soda Lake 3D seismic survey, the strain tensor produced is comparable in orientation to Basin and Range strain but has larger magnitudes. To quantify deformation within the Soda Lake 3D seismic survey, we calculate fault dip and offset of a deformed paleo-planer lacustrine mudstone. Plotting the mean dip direction of the faults in the seismic reflectivity, matches the mean surrounding GPS extensional direction, suggesting fault displacement is likely to be normal dipslip. Using a minimum age of 0.51 Ma from nearby sedimentation rates, the measured extension across the 5.4 km length of this study has a rate of 0.19 mm/yr. This is quite a high value for Basin and Range extension and it is likely a result of some influence from the Northern Walker Lane. The lack of an obvious piercing point for shear observed within the seismic volume precludes a clear estimate of strike-slip related motion within the Soda Lake 3D seismic survey. Clear extension and a large fault bend, indicates a localized relay ramp model. With focused extension indicated by two late Quaternary extrusive volcanic bodies, a model of a transtensional pull-apart basin is also considered. Given the few mapped intrabasinal faults at the surface, this study gives a unique view into fault offsets inside the Carson Sink.</p>

<p> Aeromagnetic data are used to better understand the geology and mineral resources near the Late Cretaceous Pebble porphyry Cu-Au-Mo deposit in southwestern Alaska. The reduced-to-pole (RTP) transformation of regional-scale aeromagnetic data show that the Pebble deposit is within a cluster of magnetic anomaly highs. Similar to Pebble, the Iliamna, Kijik, and Neacola porphyry copper occurrences are in magnetic highs that trend northeast along the crustal-scale Lake Clark fault. A high-amplitude, short- to moderate-wavelength anomaly is centered over the Kemuk occurrence, an Alaska-type ultramafic complex. Similar anomalies are found west and north of Kemuk. A moderate-amplitude, moderate-wavelength magnetic low surrounded by a moderate-amplitude, short-wavelength magnetic high is associated with the gold-bearing Shotgun intrusive complex. The RTP transformation of the district-scale aeromagnetic data acquired over Pebble permits differentiation of a variety of Jurassic to Tertiary magmatic rock suites. Jura-Cretaceous basalt and gabbro units and Late Cretaceous biotite pyroxenite and granodiorite rocks produce magnetic highs. Tertiary basalt units also produce magnetic highs, but appear to be volumetrically minor. Eocene monzonite units have associated magnetic lows. The RTP data do not suggest a magnetite-rich hydrothermal system at the Pebble deposit. The 10 km upward continuation transformation of the regional-scale data shows a linear northeast trend of magnetic anomaly highs. These anomalies are spatially correlated with Late Cretaceous igneous rocks and in the Pebble district are centered over the granodiorite rocks genetically related to porphyry copper systems. The spacing of these anomalies is similar to patterns shown by the numerous porphyry copper deposits in northern Chile. These anomalies are interpreted to reflect a Late Cretaceous magmatic arc that is favorable for additional discoveries of Late Cretaceous porphyry copper systems in southwestern Alaska. Aeromagnetic data help to understand the three-dimensional distribution of plutonic rocks near the Pebble porphyry copper deposit. Magnetic susceptibility measurements show that rocks in the Pebble district are more magnetic than rocks of comparable compositions in the Pike Creek-Stuyahok Hills volcano-plutonic complex. The reduced-to-pole transformation of the aeromagnetic data demonstrates that the older rocks in the Pebble district produce strong magnetic anomaly highs. The tilt derivative transformation highlights a strong, northeast-trending structural grain attributed to Tertiary volcanic rocks. Multiscale edge detection maps near-surface magnetic sources that are mostly outward dipping and coalesce at depth in the Pebble district. The total horizontal gradient of the 10 km upward continued magnetic data map a circular, deep magnetic contact along which the porphyry deposits occur. Forward and inverse magnetic modeling show that the magnetic rocks in the Pebble district extend to depths greater than 9 km. The magnetic inversion is constrained by a near-surface, three-dimensional geologic model that is attributed with measured magnetic susceptibilities from various rock types in the region. The inversion results indicate that several near-surface magnetic features with moderate susceptibilities converge with depth into magnetic bodies with higher susceptibilities. This deep magnetic source appears to rise towards the surface in several areas. An isosurface value of 0.02 SI is used to depict the magnetic contact between outcropping granodiorite and non-magnetic sedimentary host rocks. The contact is shown to be outward dipping. At depths around 5 km nearly the entire model exceeds the isosurface value indicating the limits of non-magnetic host material. The inversion results show the presence of a relatively deep, northeast trending magnetic low that parallels lineaments mapped by the tilt derivative. This deep low represents a strand of the Lake Clark fault. The geodynamic setting of an accreted island-arc terrane represent a region in which several types of mineral resources may occur. The mineral resources from southwest Alaska are classified into greenstone-hosted, oxidized intrusion-related, reduced intrusion-related, and epithermal. Aeromagnetic data are related to the classified mineral resource and outcropping geology to better understand the distribution of gold-rich mineral resources. Three magnetic domains are defined by the reduced-to-pole, upward continue, and tilt derivative transforms. The greenstone-hosted mineral resources that include VMS are mapped along magnetic lineaments mostly landward of the accreted island-arc. The oxidized intrusion-related mineral resources that include porphyry copper, skarn, and Alaska-type ultramafic-mafic complexes occur along magnetic anomaly highs in the Peninsular and Kahiltna domains. Characteristic short wavelength, high amplitude magnetic anomalies suggest additional Alaska-type ultramafic-mafic complexes and skarn resources in the Kahiltna and Kuskokwim domain. Magnetic depth estimates indicate potential greenstone-hosted and oxidized intrusion-related resources occur beneath 100 m of glacial deposits. Reduced intrusion-related resources are best imaged in the more landward, Kuskokwim magnetic domain. Epithermal resources are not well imaged. The mineral potential map highlights areas most favorable for additional mineral resources.</p>

<p>The THUMS-Huntington Beach fault branches from the Palos Verdes fault zone and south of that point forms the southwestern border of the Wilmington and Huntington Beach anticlines. Wilmington and Huntington Beach oil fields are located nearby, with timing and trapping mechanisms closely related to the evolution of the California Continental Borderland. The T-HBF, being part of Inner Borderland, is associated with change in vector of regional stress. Previously, this fault has been interpreted as a discontinuous feature. Correlation of newly acquired 2-D and existing industry 2-D and 3-D seismic and well data made it possible to identify that this is a right-slip fault zone with three segments. The T-HBF is striking northwest and has an average dip of 75&deg; to the northeast. Wilmington and Huntington Beach anticlines are inverted basins formed as structural lows and then uplifted as a result of T-HBF activity in late Miocene-early Pliocene time. </p>

<p>Features observed on a seismic horizon at or near the Cretaceous-Paleogene boundary in a roughly 200 square km (77 square miles) 3D seismic survey from northern Louisiana resemble large subaqueous dunes or &ldquo;mega-ripples.&rdquo; It is hypothesized that these features may represent subaqueous dunes emplaced by tsunami waves generated by the end-Cretaceous Chicxulub Impact event on the Yucat&aacute;n Peninsula. Seismic data are scrutinized to determine whether or not features observed in the data represent true subsurface geometries. Other hypotheses are tested including the possibility that these features may represent seismic data acquisition footprints, a portion of a slump deposit, or a portion of an aeolian dune field. Results indicate that it is very unlikely that these features represent an acquisition footprint, a slump deposit, or an aeolian dune field. Well-logs are interpreted and seismic velocities are calculated to determine a range of possible lithologies within the Upper Cretaceous interval but the results of the two methods are inconsistent with each other. </p>

<p> Brittleness is a key characteristic for effective reservoir stimulation and is mainly controlled by mineralogy in unconventional reservoirs. Unfortunately, there is no universally accepted means of predicting brittleness from measures made in wells or from surface seismic data. Brittleness indices (BI) are based on mineralogy, while brittleness average estimations are based on Young's modulus and Poisson's ratio. I evaluate two of the more popular brittleness estimation techniques and apply them to a Barnett Shale seismic survey in order to estimate its geomechanical properties. Using specialized logging tools such as elemental capture tool, density, and P- and S wave sonic logs calibrated to previous core descriptions and laboratory measurements, I create a survey-specific BI template in Young's modulus versus Poisson's ratio or alternatively &lambda;&rho; versus &mu;&rho; space. I use this template to predict BI from elastic parameters computed from surface seismic data, providing a continuous estimate of BI estimate in the Barnett Shale survey. Extracting &lambda;&rho;-&mu;&rho; values from microseismic event locations, I compute brittleness index from the template and find that most microsemic events occur in the more brittle part of the reservoir. My template is validated through a suite of microseismic experiments that shows most events occurring in brittle zones, fewer events in the ductile shale, and fewer events still in the limestone fracture barriers. </p><p> Estimated ultimate recovery (EUR) is an estimate of the expected total production of oil and/or gas for the economic life of a well and is widely used in the evaluation of resource play reserves. In the literature it is possible to find several approaches for forecasting purposes and economic analyses. However, the extension to newer infill wells is somewhat challenging because production forecasts in unconventional reservoirs are a function of both completion effectiveness and reservoir quality. For shale gas reservoirs, completion effectiveness is a function not only of the length of the horizontal wells, but also of the number and size of the hydraulic fracture treatments in a multistage completion. These considerations also include the volume of proppant placed, proppant concentration, total perforation length, and number of clusters, while reservoir quality is dependent on properties such as the spatial variations in permeability, porosity, stress, and mechanical properties. I evaluate parametric methods such as multi-linear regression, and compare it to a non-parameteric ACE to better correlate production to engineering attributes for two datasets in the Haynesville Shale play and the Barnett Shale. I find that the parametric methods are useful for an exploratory analysis of the relationship among several variables and are useful to guide the selection of a more sophisticated parametric functional form, when the underlying functional relationship is unknown. Non-parametric regression, on the other hand, is entirely data-driven and does not rely on a pre-specified functional forms. The transformations generated by the ACE algorithm facilitate the identification of appropriate, and possibly meaningful, functional forms.</p>

<p> The calculated extension (~111 km) across the Woodlark rift is incompatible with the > 130 km needed to exhume the Metamorphic Core Complexes on shallow angle faults (&lt; 30&deg;) using N-S extension in the Woodlark Basin. High resolution bathymetry, seismicity, and seismic reflection data indicate that the Nubara Fault continues west of the Trobriand Trough, intersects the Woodlark spreading center, and forms the northern boundary of the Woodlark plate and the southern boundary of the Trobriand plate. The newly defined Trobriand plate, to the north of this boundary, has moved SW-NE along the right lateral Nubara Fault, creating SW-NE extension in the region bounded by the MCC's of the D'Entrecasteaux Islands and Moresby Seamount. Gravity and bathymetry data extracted along four transect lines were used to model the gravity and flexure across the Nubara Fault boundary. Differences exist in the elastic thickness between the northern and southern parts of the lines at the Metamorphic Core Complexes of Goodenough Island (Te_south = 5.7 x 103 m; Te_north = 6.1 x 103 m) and Fergusson Island (Te_south = 1.2 x 103 m; Te_north = 5.5 x 103 m). Differences in the elastic strength of the lithosphere also exist at Moresby Seamount (Te_south = 4.2 x 103 m; Te_north = 4.7 x 103 m) and Egum Atoll (Te_south =7.5 x 103 m; Te_north = 1.3 x 104 m). The differences between the northern and southern parts of each transect line imply an east-west boundary that is interpreted to be the Nubara Fault. The opening of the Woodlark Basin resulted in the rotation of the Papuan Peninsula and the Woodlark Rise, strike slip motion between the Solomon Sea and the Woodlark Basin at the Nubara Fault, and the formation of the PAC-SOL-WLK; SOL-WLK-TRB triple junctions. The intersection of the Woodlark Spreading Center with the Nubara Fault added the AUS-WLK-TRB triple junction and established the Nubara Fault as the northern boundary of the Woodlark plate.</p>