Browsing by Subject "Thermal history"
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Item Structural diagenetic attributes of the late Cretaceous Williams fork sandstones with implications for petrophysical interpretation and fracture prediction, Piceance Basin, Colorado(2010-05) Ozkan, Aysen, 1974-; Laubach, Stephen E. (Stephen Ernest), 1955-; Milliken, K. L.; Horton, Brian; Steel, Ron; Tinker, Scott; Bonnell, LindaDiagenetic and structural aspects of tight gas sandstones must be addressed concurrently in order to fully understand low-permeability sandstones and to better predict their reservoir quality attributes that arise from a combination of pore-scale and fracture distribution characteristics. This dissertation focuses on aspects of rock evolution that are germane to concurrent structural and diagenetic evolution, such as loading and thermal history, rock mechanical property evolution, and fracture timing. I tested the hypothesis that the cement precipitation step, governed by thermal exposure and grain surface attributes, governs how sandstone attributes evolve using observations from the Late Cretaceous Williams Fork sandstones from the Piceance Basin, Colorado. My research shows that essential information for predicting and understanding fracture patterns in sandstone can be obtained by unraveling cement precipitation (diagenetic) history. Fractures depend on the mechanical properties existing during fracture growth. I show that key rock mechanical properties (subcritical crack index, Young's modulus and Poisson's ratio), petrophysical behavior, and reservoir quality depend in a systematic way on time-temperature history and the intrinsic grain surface attributes of these sandstones. I classified the Williams Fork lithofacies petrographically and correlated those with log responses to create a model that can be used to predict reservoir quality and diagenesis directly from well logs. I determined rock mechanical characteristics by measuring the subcritical crack index (SCI), a mechanical property that influences fracture distribution characteristics, and by examining log-derived bulk mechanical properties. To quantify the influence of quartz cementation on the SCI and to determine the range of SCI values for sandstone of given framework composition at different diagenetic stages, I measured SCI on Williams Fork core samples and their outcrop equivalents. Diagenetic modeling is applied to determine the sandstone characteristics during fracturing.Item Thermal history correlation with mechanical properties for polymer selective laser sintering (SLS)(2017-05) Taylor, Samantha Sparr; Beaman, Joseph J.This thesis investigates the in-situ thermal history of parts manufactured with the Selective Laser Sintering (SLS) process. It compares the effectiveness of two different cameras, a stationary reference mid-wave infrared (IR) and a bore-sighted mid-wave IR camera, by evaluating correlations between strength, elongation, and fracture location to the observed thermal history of the selective laser sintered parts produced. ZYX tensile bars were built to leverage the high dependence of tensile strength on interlayer bonding, which is generally assumed to be related to thermal conditions from layer to layer. Various thermal history analysis methods, for example: cold subregion temperature, average layer temperature, and outline average temperature, were examined to discover the best method for predicting fracture location and correlating with build strength. In addition, several smoothing techniques that reduced the noise over time when using the different thermal analysis methods were assessed in their ability to improve the correlation of the given thermal method to the mechanical strength and fracture location.