In this research project the author introduces the use of geometrical modelling techniques alongside geostatistical methods to model a stratigraphic orebody and to present a graphics display system developed as a fIrst step towards a general integrated system for computer aided design and planning in mining. Geometrical modelling techniques and geostatistical methods are combined to carry out the process of modelling a stratigraphic orebody. From a mining point of view, there are two main features of interest in a stratigraphic ore-body: a-The modelling of the geometry of the orebody. b- The modelling (estimation) of the physical properties (grades, etc ... ) of the orebody. The first feature is the subject of this research project. Modelling methods and techniques developed elsewhere and for different applications, such as Computer Aided Design, have been applied successfully to model the geometry of stratigraphic orebodies. The modelling process consists of the applications of surface modelling techniques to represent the hangingwall and the footwall of the stratigraphic orebody and thereby to produce the space where the physical properties are geostatistically to be estimated. The graphics display system is presented to highlight the use of computer graphics techniques to communicate graphically all sorts of information concerning the modelling of stratigraphic orebodies and also to display the end product of the modelling process, such as cross-sections, plane-sections, wireframe and solid models of the orebody. The graphics system itself is part of a computer based system for mine design and planning similar to computer aided design systems used mainly in the manufacturing industry. The presentation of the research project in this thesis started by the review of the literature of some existing ore reserves estimation methods in the mineral industry, particularly geostatistical methods. Then an overview and the scope of this research project have been given. The second chapter describes the type of data which could be encountered while building a geometrical model of a stratigraphic orebody and a description of data from a nickel vein deposit used as a case study for this research project. The accumulations have been estimated geostatistically subject to geometrical control. The geometrical control concept and surface modelling techniques are presented in chapter three together with the numerical application of modelling a nickel vein deposit using two different surface modelling techniques. Chapter four describes the graphics display system developed to display several geometric features of stratigraphic orebodies in two and three dimensions. The summary of this research project and some concluding remarks are given in chapter five.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 110-132).

The global ocean overturning circulation is a major means of distributing heat around the Earth, and an important trigger or amplifier of climate change. The formation of North Atlantic Deep Water (NADW) is a major driver of the critical Atlantic arm of the global system, the Atlantic Meridional Overturning Circulation (AMOC). Paleoceanographic studies have suggested considerable reorganizations of AMOC under varying climate conditions, through changes in the southward export of past analogs of NADW (referred to in this thesis as “North Atlantic-sourced waters” or NASW). Here, through measurements of Nd isotope ratios of Fe-Mn oxide encrusted foraminifera from Deep Sea Drilling Project (DSDP) Site 607, located in the present-day core of NADW, new constraints on the composition of the North Atlantic AMOC end-member through time are provided. Moreover, this dissertation reconstructs bottom water masses in the deep North Atlantic, and by inference changes in AMOC, under interglacial and glacial conditions, and across important shifts in the climate system such as the Mid-Pleistocene Transition (MPT; ~1250-650 ka) and the intensification of Northern Hemisphere glaciation (iNHG; ~3.6-2.4 Ma). Chapter 1 focuses on constraining the Nd isotope composition of NASW and changes in its southward export to Site 607 over the last 1.5 Myr. The results suggest increased incursions of southern-sourced waters (SSW) in the deep North Atlantic between ~960 and 860 ka, suggesting that a major AMOC disruption previously observed in the South Atlantic over the same time interval was a basin-wide event. Excluding this interval of AMOC disruption and a 200-kyr-long prolonged interval of weak AMOC that followed, interglacials over the last 1.5 Myr were characterized by the prevalence of water masses similar to the present-day NADW in the deep Atlantic, indicating consistent interglacial AMOC dynamics and North Atlantic end-member. In contrast, glacials were marked by SSW incursions, which further intensified during and after the MPT, suggesting a fundamental change in glacial AMOC. Chapter 2 investigates heightened terrigenous signals right before the onset of the MPT-AMOC disruption seen in the 1.5-Myr-long authigenic Nd isotope record from the first chapter, by further increasing the temporal resolution of the record. Results indicate pronounced inputs of old continental material in the North Atlantic across ~1250-950 ka, perhaps through intense glacial erosion of the cratonic shields in the region. These lend support for the regolith hypothesis for the MPT, whereby removal of regolith via ice-sheet erosion exposed high-friction crystalline bedrock that facilitated thicker and stable ice sheets, fundamentally changing their response to orbital forcing. Chapter 3 provides terrestrial evidence for the erosional events explored in the second chapter, through measurements of major and trace element concentrations, Nd-Sr-Pb isotope ratios, and K-Ar ages on detritus fractions of the Site 607 sediment core. While the detritus deposited at Site 607 during glacials across ~1250-960 ka are more chemically weathered and resemble the average shale that originated from older North Atlantic continental sources such as the late Archean and Proterozoic rocks of the Superior and Churchill Province, and West Greenland, less chemically weathered detritus resembling the average upper continental crust from continental sources such as the Grenville Province and the Appalachians comprise the glacial terrigenous sediments at Site 607 after ~960 ka. These findings further support the regolith hypothesis for the MPT and underline the impact of the Northern Hemisphere erosional events suggested in Chapter 2. Chapter 4 focuses on reconstructing changes in the AMOC and NASW exports in the North Atlantic during the Late Pliocene-Early Pleistocene, by combining a newly generated Nd isotope data at Site 607 covering ~1.5-2.4 Ma with a published record at the same site covering ~2.4-3.3 Ma during the iNHG. The composite record suggests an overall strong NASW export in the North Atlantic during both interglacials and glacials. However, the Nd isotope composition of NASW inferred from the record indicates that the proportions of deep waters from the Greenland-Iceland-Norwegian seas (GINS) in NASW were greater during the Late Pliocene and the first ~500-600 kyr into the Early Pleistocene, relative to the rest of the Pleistocene and today. A gradual increase of sea ice cover in the GINS during glacials across ~2.5-2 Ma may have eventually led to a perennial ice cover in the region and significantly reduced exports of overflow waters to the North Atlantic. By ~2 Ma, the modern Nd isotope composition of NADW was obtained. Chapter 5 aims to qualitatively assess the effectiveness of Nd isotope ratios as a paleoceanographic tracer, through a compilation of Nd isotope records from multiple sites located throughout the Atlantic Ocean. The Nd isotope ratios observed at the sites are consistent with NASW-SSW gradients expected from the AMOC structure and reflect even the local water mass structure and bathymetric settings, confirming the quasi-conservative nature of seawater Nd isotope ratios. An additional comparison of published Atlantic Nd isotope records for the Last Glacial Maximum to Holocene also demonstrates that authigenic Nd isotope ratios reflect past changes in water mass mixing in the Atlantic. These observations reaffirm that Nd isotopes are an effective paleoceanographic tool.

The modern plate tectonic paradigm provides a predictive model to understand what mediates dynamic processes at both plate margins and intraplate settings. At some locations on the Earth, the geological record provides evidence of apparent violations of this theoretical framework. In this dissertation, I examine a region on the rifted continental margin of Eastern North America, where at least four distinct episodes of magmatism occurred (in the Late Triassic, Early Jurassic, Early Cretaceous) since the onset of rifting and ultimate breakup of the supercontinent Pangea. It also coincides with a present-day low seismic velocity anomaly in the upper mantle. No other region on the Eastern North American Margin has a record of such anomalous dynamic processes occurring and persisting for more than 200 Myr. In this dissertation, I primarily use zircon U-Pb geochronology to establish the basic chronological framework in which magmatic and magmatic-hydrothermal systems in this region existed and persisted, establishing the temporal parameter space in which it will be possible to test geodynamic mechanisms for their formation. In Chapter 2, I use ultra-high precision zircon U-Pb geochronology via Chemical Abrasion-Isotope Dilution-Thermal Ionization Mass Spectrometry (CA-ID-TIMS) to test whether the onset of magmatism in the largest igneous body in this region (the White Mountain Batholith) is linked to the eruption of the vast flood basalts within the Central Atlantic Magmatic Province (CAMP) and whether its apparent duration is indeed > 50 Myr, as previous workers using whole rock K-Ar and mineral Ar-Ar geochronologic methods suggest. My work uncovered a previously unknown episode of rift-related magmatism in the region that precedes the both the CAMP and the emplacement of the White Mountain Batholith by 3 – 5 Myr. In Chapter 3, I use a combination of high-precision zircon U-Pb geochronology and absolute plate motion models to test whether the Cretaceous igneous province in this region resulted from hot spot magmatism as North America moved over the purported Great Meteor Hotspot. These results cannot falsify the hotspot hypothesis and the new zircon U-Pb ages therefore provide the best available chronological constraints for one of the longest-lived hot spot tracks on the Earth. In Chapter 4, motivated by the confirmation of age discrepancies between low- and intermediate-temperature chronometers and the zircon U-Pb ages presented in Chapter 2, I use a combination of both CA-ID-TIMS and LA-ICP-MS zircon U-Pb geochronologic techniques to place constraints on the timing and duration of magmatism for the Late Triassic-Early Jurassic province. The results of this chapter demonstrate that the magmatism of the White Mountain Magma Series occurs in discrete pulses through much of the Jurassic. Together with zircon Hf isotopic analyses from select samples, I synthesize these age results and construct a hypothesis testing framework in which it will be possible for future investigators to unravel the geodynamic complexities in this region. I provide recommendations for future work and emphasize the need for unified approaches coupling geochronology, geochemistry, and geophysics, to test the range of possible mechanisms responsible for these episodes of anomalous tectono-magmatic activity.

We use sedimentary structures, fossil evidence, sediment petrophysical properties, and geochemistry to investigate past climate. In the first two chapters, we outline a toolkit to identify the presence of ice rafted debris in lake sediments using a combination of grain size analysis, computed tomography and image analysis. We apply this toolkit to sediments from the early Mesozoic, paleo-Arctic Junggar Basin, and describe the first evidence of continental freezing from this time period. We also discuss characteristics of algae rafted debris; clusters of coarse sediment suspended in a fine sediment matrix can be deposited without freezing conditions and may be a confounding factor in the geological record. In chapters three and four, we examine sediment cores from the coast of New York and the effects of sea level rise after the last deglaciation. New AMS radiocarbon dates from submerged terrestrial sediments on the US Atlantic continental shelf provide key constraints on the timing of marine transgression following the retreat of the Laurentide Ice Sheet. We use sediment elevation tables (SETs) and sediment cores to measure the accretion rate in a Hudson River tidal wetland to determine its vulnerability to sea level rise. We find that SETs overestimate accretion and underestimate vulnerability on timescales relevant to coastal flooding risk. Together, these chapters outline novel tools and approaches in imaging, geochemistry, and micro-stratigraphy broadly applicable for investigations on paleoclimate research through time and space.

Leakage of stored bulk phase CO₂ is one risk for sequestration in deep saline aquifers. As the less dense CO₂ migrates upward within a storage formation or in layers above the formation, the security of its storage depends upon the trapping mechanisms that counteract the migration. The trapping mechanism motivating this research is local capillary trapping (LCT), which occurs during buoyancy-driven migration of bulk phase CO₂ within a saline aquifer with spatially heterogeneous petrophysical properties. When a CO₂ plume rising by buoyancy encounters a region where capillary entry pressure is locally larger than average, CO₂ accumulates beneath the region. One benefit of LCT, applied specifically to CO₂ sequestration and storage, is that saturation of stored CO₂ phase is larger than the saturation for other permanent trapping mechanisms. Another potential benefit is security: CO₂ that occupies local capillary traps remains there, even if the overlying formation that provides primary containment were to be compromised and allow leakage. Most work on LCT has involved numerical simulation (Saadatpoor 2010, Ganesh 2012); the research work presented here is a step toward understanding local capillary trapping at the bench scale. An apparatus and set of fluids are described which allow examining the extent of local capillary trapping, i.e. buoyant nonwetting phase immobilization beneath small-scale capillary barriers, which can be expected in typical heterogeneous storage formation. The bench scale environment analogous to CO₂ and brine in a saline aquifer is created in a quasi-two dimensional experimental apparatus with dimension of 63 cm by 63 cm by 5 cm, which allows for observation of plume migration with physically representative properties but at experimentally convenient ambient conditions. A surrogate fluid pair is developed to mimic the density, viscosity and interfacial tension relationship found at pressure and temperature typical of storage aquifers. Porous media heterogeneity, pressure boundary conditions, migration modes of uprising nonwetting phase, and presence of fracture/breach in the capillary barrier are studied in series of experiments for their influences on LCT. A variety of heterogeneous porous media made of a range of sizes of loosely packed silica beads are used to validate and test the persistence of local capillary trapping mechanism. By adjusting the boundary conditions (fluid levels in reservoirs attached to top and to bottom ports of the apparatus), the capillary pressure gradient across the domain was manipulated. Experiments were conducted with and without the presence of fracture/potential leakage pathway in the capillary seal. The trapped buoyant phase remained secure beneath the local capillary barriers, as long as the effective capillary pressure exerted by the trapped phase (proportional to column height of the phase) is smaller than the capillary entry pressure of the barrier. The local capillary trapping mechanism remained persistent even under forced imbibition, in which a significantly higher hydraulic potential gradient, and therefore a larger gradient in capillary pressure, was applied to the system. The column height of buoyant fluid that remained beneath the local capillary barrier was smaller by a factor corresponding to the increase in capillary pressure gradient. Mimicking a breach of the caprock by opening valves at the top of the apparatus allowed buoyant mobile phase held beneath the valves to escape, but buoyant phase held in local traps at saturations above residual, and therefore potentially mobile, was undisturbed. This work provides systematic validation of a novel concept, namely the long-term security of CO₂ that fills local (small-scale) capillary traps in heterogeneous storage formations. Results from this work reveal the first ever unequivocal experimental evidence on persistence of local capillary trapping mechanism. Attempts to quantify the nonwetting phase saturation and extent of LCT persistence serve as the initial steps to potentially reduce the risks associated with long-term storage security. / text

Master of Science / Department of Geology / Matthew W. Totten / The area of study for this project is the Leach Field, which is located in Jackson County, Kansas. Production in the Leach Field has historically been disappointing, with 388,787 barrels of oil being produced since the field’s discovery in 1963 (KGS, 2015). Production of the field has been highly variable, with only 20,568 barrels of oil being produced in the last 20 years. Economic and other concerns that have impacted production and production rates of the field include: low oil prices soon after its discovery, numerous changes of ownership, and lack of significant production infrastructure in the area. Stroke of Luck Energy & Exploration, LLC. has recently purchased the majority of the leases and wells in the Leach Field, and is reestablishing the field as a productive oil field. Plans include: washing down several plugged and abandoned wells, and drill new wells to increase production in the field. The goal of this study was to determine the major geologic factors controlling reservoir quality in the Hunton and Viola Limestone Formations in the Leach Field, so that a future exploration model can be developed to help increase and stabilize the field's overall production. This model was created by applying several testing methods including: well logging analysis, microscope analysis, and subsurface mapping. Based on these results it was determined that the quality of the reservoir rocks is controlled by the degree of dolomitizaiton in both formations. Reservoir quality is as important as structure in determining well productivity in the Leach Field.

The injection operator for a carbon dioxide sequestration project must control the reservoir and associated pore space within the project boundaries to allow for orderly development of the storage facility. A large number of interest owners within a project area is likely to make reaching unanimous agreement among all owners of pore space unlikely, and thus control of the reservoir difficult. In order to facilitate geologic sequestration of carbon dioxide on privately owned land in the United States, or on land for which the minerals or pore space are privately owned, a scheme for aggregating the ownership of pore space is needed. To allow geologic sequestration projects to move forward with less than unanimous consent of interest owners, states can employ various methods of aggregating pore space ownership. This paper examines oil and gas unitization statues and statutes creating groundwater districts to find legislative regimes useful for achieving pore space ownership aggregation. Among the approaches discussed, aggregation of pore space ownership through a unitization model is the most likely choice. Taking that one step further and setting up new unit operating agreements for enhanced oil recovery to serve as a repository for incremental geologic sequestration, and eventual full sequestration activities, provides a firm path toward reducing carbon dioxide emissions while respecting property rights. This paper also compares the few existing pore space aggregation statutes in the United States, which achieve aggregation of pore space ownership through either unitization or eminent domain. The state that appears to be the best equipped to deal with aggregation of pore space ownership is Wyoming. Wyoming has been a leader in developing legislation to deal with pore space ownership before other states. North Dakota and Utah are also very well situated to move forward with carbon sequestration activities. / text

No description available.

<P> This study investigates ways to improve the accuracy of 3D geologic models by assessing the impact of data quality, grid complexity, data quantity and distribution, interpolation algorithm and program selection on model accuracy. The first component of this research examines the impact of variable quality data on 3D model outputs and presents a new methodology to optimize the impact of high quality data, while minimizing the impact of low quality data on the model results. This 'Quality Weighted' modelling approach greatly improves model accuracy when compared with un-weighted models. </p> <p> The second component of the research assesses the variability and influence of data quantity, data distribution, algorithm selection, and program selection on the accuracy of 3D geologic models. A series of synthetic grids representing environments of varying complexity were created from which data subsets were extracted using specially developed MA TLAB scripts. The modelled data were compared back to the actual synthetic values and statistical tests were conducted to quantify the impact of each variable on the accuracy of the model predictions. The results indicate that grid complexity is the predominant control on model accuracy, more data do not necessarily produce more accurate models, and data distribution is particularly important when relatively simple environments are modelled. A major finding of this study is that in some situations, the software program selected for modelling can have a greater influence on model accuracy than the algorithm used for interpolation. When modelling spatial data there is always a high level of uncertainty, especially in subsurface environments where the unit(s) of interest are defined by data only available in select locations. The research presented in this thesis can be used to guide the selection of modelling parameters used in 3D subsurface investigations and will allow the more effective and efficient creation of accurate 3D models. </p> / Thesis / Doctor of Philosophy (PhD)