3 Matching Results

Search Results

Advanced search parameters have been applied.

Final Report, DE-FG02-92ER14261, Pore Scale Geometric and Fluid Distribution Analysis

Description: The elucidation of the relationship between pore scale structure and fluid flow in porous media is a fundamental problem of long standing interest. Incomplete characterization of medium properties continues to be a limiting factor in accurate field scale simulations. The accomplishments of this grant have kept us at the forefront in investigating the applicability of X-ray computed microtomography (XCMT) as a tool for contributing to the understanding of this relationship. Specific accomplishments have been achieved in four areas: - development of numerical algorithms (largely in the field of computational geometry) to provide automated recognition of and measurements on features of interest in the pore space. These algorithms have been embodied in a software package, 3DMA-Rock. - application of these algorithms to extensive studies of the pore space of sandstones. - application of these algorithms to studies of fluid (oil/water) partitioning in the pore space of Berea sandstone and polyethylene models. - technology transfer.
Date: January 21, 2005
Creator: Lindquist, W. Brent
Partner: UNT Libraries Government Documents Department

Methane Hydrate Formation and Dissocation in a Partially Saturated Sand--Measurements and Observations

Description: We performed a sequence of tests on a partially water-saturated sand sample contained in an x-ray transparent aluminum pressure vessel that is conducive to x-ray computed tomography (CT) observation. These tests were performed to gather data for estimation of thermal properties of the sand/water/gas system and the sand/hydrate/water/gas systems, as well as data to evaluate the kinetic nature of hydrate dissociation. The tests included mild thermal perturbations for the estimation of the thermal properties of the sand/water/gas system, hydrate formation, thermal perturbations with hydrate in the stability zone, hydrate dissociation through thermal stimulation, additional hydrate formation, and hydrate dissociation through depressurization with thermal stimulation. Density changes throughout the sample were observed as a result of hydrate formation and dissociation, and these processes induced capillary pressure changes that altered local water saturation.
Date: March 1, 2005
Creator: Kneafsey, Timothy J.; Tomutsa, Liviu; Moridis, George J.; Seol, Yongkoo; Freifeld, Barry; Taylor, Charles E. et al.
Partner: UNT Libraries Government Documents Department

Experimental Investigation of Material Flows Within FSWs Using 3D Tomography

Description: There exists significant prior work using tracers or pre-placed hardened markers within friction stir welding (FSWing) to experimentally explore material flow within the FSW process. Our experiments replaced markers with a thin sheet of copper foil placed between the 6061 aluminum lap and butt joints that were then welded. The absorption characteristics of x-rays for copper and aluminum are significantly different allowing for non-destructive evaluation (NDE) methods such as x-ray computed tomography (CT) to be used to demonstrate the material movement within the weldment on a much larger scale than previously shown. 3D CT reconstruction of the copper components of the weldment allows for a unique view into the final turbulent state of the welding process as process parameters are varied. The x-ray CT data of a section of the weld region was collected using a cone-beam x-ray imaging system developed at the INL. Six-hundred projections were collected over 360-degrees using a 160-kVp Bremsstrahlung x-ray generator (25-micrometer focal spot) and amorphoussilicon x-ray detector. The region of the object that was imaged was about 3cm tall and 1.5cm x 1cm in cross section, and was imaged at a magnification of about 3.6x. The data were reconstructed on a 0.5x0.5x0.5 mm3 voxel grid. After reconstruction, the aluminum and copper could be easily discriminated using a gray level threshold allowing visualization of the copper components. Fractal analysis of the tomographic reconstructed material topology is investigated as a means to quantify macro level material flow based on process parameters. The results of multi-pass FSWs show increased refinement of the copper trace material. Implications of these techniques for quantifying process flow are discussed.
Date: June 1, 2008
Creator: Tolle, Charles R.; White, Timothy A.; Miller, Karen S.; Clark, Denis E. & Smartt, Herschel B.
Partner: UNT Libraries Government Documents Department