Thesis (M.S.)--Texas A & M University, 2003. / "Major Subject: Petroleum Engineering." Title from author supplied metadata. Includes bibliographical references.

<p> It has been reported that the Macondo tragedy was caused by a faulty cementing operation. This, in turn, has forced operators to pay special attention to this aspect of well completion. One of the contributing factors to the faulty cementing operation of Macondo is said to be an insufficient number of casing centralizers. This is important because the success of any casing cementing operation is largely dependent on the centralization of the casing in the wellbore.</p><p> Centralizers are placed on the casing strings at predetermined distances in an effort to retain the casing in the center of the wellbore, thereby maximizing the coverage of cement around the casing. Placement, as well as the number, of centralizers is dependent on the standoff of the casing in the wellbore. Standoff is defined as the minimum distance between the outer diameter of the casing and the wellbore.</p><p> For casings under tension, API has recommended formulas to calculate casing standoff in 3D wellbores, which takes into account the inclination and azimuth angles. In addition, literature is available that considers casing under compression due to the fluid forces acting on the casing string and shows a considerable difference in standoff when considering compression as compared to tension alone. Currently all available literature considers the wellbore as rigid only. This paper considers the formation type, ranging from unconsolidated sand to shale, and calculates its effect on standoff. The results show that the formation type may significantly affect the outcome of standoff, and therefore should be considered when calculating standoff. </p>

This study created a new tectonic model for the Arctic Alaska terrane (AAT) by connecting attributes interpreted from surface and subsurface maps. Lineaments that cross the Brooks Range and North Slope proclaim the presence of basement fault blocks trending to the northeast that locally are aligned with streams, coast and lake shorelines, submarine canyons, and periglacial features. These landforms and anomalies reflect upward propagation of long-lived transcurrent and rift fault fabrics. Facies mapping and analysis of heat-flow effects on permafrost, and data from aeromagnetic, gravity and reflection seismic surveys, support the correlation of basement faulting with geomorphic patterns. The conjugate pattern of fault blocks, seen across Paleozoic- and Mesozoic-age passive margin sequences, resembles a piano keyboard and was inherited from older rift margin and transcurrent-transfer faults. Seismic data and North Slope oil-reservoir characteristics reveal complex fault-block boundaries, and common fault reactivation and structural inversion. The rigid North American craton in the Yukon Territory directs deformation westward leading to continued crustal indention, migration of basement blocks, and thrusting of cover rocks north of the Arctic oroclinal bend. Differential south-vergent underthrusting and uplift of the basement blocks of the North Slope plate has episodically segmented and partitioned strain across the overlying weaker north-vergent cover rocks of the North Alaskan plate. These tectonic controls have influenced the structural and geomorphic evolution of the North Slope-Brooks Range foothills region, including the formation of oil and gas reservoirs and mineral deposits.

<p> Foam has been widely used in the petroleum industry. The use foam as a drilling fluid takes advantages of the foam's physical properties. Foam decays into liquid after a certain time. The decay process happens faster at an elevated temperature. The research on foam thermal stability has not been thorough. This paper presents experimental research about the stability of foam from three polymers with viscosity of 10cp, 20cp, and 30cp. The stabilities of foam were tested at an elevated temperature. The most thermal stable foam among the foams provided was determined. There are some unclear behaviors that need to be studied in future work.</p>

<p>This study was motivated by how to use statistical tool to identify the candidacy wells for CO2 Capture and Sequestration based on the idea of using Artificial Neural Networks to predict the leakage index of a well. A Combined Neural-Genetic Algorithm was introduced to avoid BP neural network getting a local minimum because Genetic Algorithm simulates the survival of the fittest among individuals over consecutive generation. Based on the algorithm, 1356 lines of C code were composed using Microsoft Visual Studio 2010. The Combined Neural-Genetic Algorithm developed in this thesis is able to handle large size of data sample with at least 10 factors. Several parameters were considered as factors that may have an effect on the performance of Combined Neural-Genetic Algorithm, including the population size, max epoch, error goal, probability of crossover, probability of mutation, number of neurons in hidden layer, number of factors and size of data sample. The accuracy of the BP neural network and the CPU time are the two major parameters to evaluate the performance of the Combined Neural-Genetic Algorithm. A sensitivity analysis was performed to identify the effect these factor have on the performance. Based on the result of the sensitivity analysis, some recommendations are provided about initializing these factors.

Gas flow behavior from a spherical source is explored by using linear and nonlinear models, not only in terms of pressure but also in terms of flux. The approach considers dimensionless parameters scaling both radius and time. Specific observations are made for large, moderate, and small time conditions. At large time, the nonlinear model becomes a linear ordinary differential equation with pressure solution independent of the material. However, for moderate and small scaled times this is not the case. The nonlinear model must be solved by using either linear approximations, semi-analytical, or numerical procedures. This model is nonlinear in the primary variable (pressure). However, appropriate mathematical manipulations allow one to change the nonlinearity into a single coefficient, depending on pressure. Focusing on the effects of this coefficient, the nonlinear solution can be confined between two linear solutions obtained by using atmospheric and boundary pressures. Appendix A is an exploration of the errors arising between the nonlinear solution and these two solutions. In Appendix B, a nonlinear model is used to find solutions for large, moderate, and small times. For large time, the case corresponds to the steady state case, and coincides with the solution presented in Appendix A. For moderate and small times the quasi-analytical approximation and the asymptotic solutions of linear and quadratic normalizations of pressure are presented. In Appendix C, simulations of gas flows in linear and nonlinear situations are made. The problem is to determine the change of air pressure in a tank when it is connected to a spherical cavity embedded in a porous medium. These changes in pressure occur when the air moves through the porous media, either for gas extraction or air injection. Both linear and nonlinear analyses require calculations of the pressure and the mass in the tank when the initial and boundary conditions change with time. For each case, gas extraction or air injection, the differences between the linear and the nonlinear models are examined to determine the suitability of the linear model.

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<p> Extreme heterogeneity in oil saturation between closely adjacent sandstone beds reflects different timing and degree of diagenesis. Understanding the distribution and origin of such heterogeneity is critical to effectively exploiting intercalated sandstone deposits within fine-grained unconventional reservoirs and in unraveling subtleties of stratigraphic traps. Sea cliff exposures at Point Fermin, California, expose a submarine channel facies within the largely hemipelagic facies. Separated by only meters, Point Fermin Sandstone is oil-saturated, whereas Altamira Shale sandstone is not. Samples were analyzed for porosity, permeability and fluid saturation in conjunction with thinsection petrographic analysis. Sandstones are primarily schist- bearing lithic arenites and the grains are cemented mostly by rhombic dolomite. Data show that both units have the same provenance but differ in the timing and type of diagenesis with shale-hosted sandstones generally showing earlier cementation. The degree and type of cementation occluded pore spaces to prevent hydrocarbon charging in the non-saturated sandstone.</p>

<p> The submarine-fan-dominated, proximal Los Angeles basin contains interstratified hemipelagic strata coeval with the widespread Miocene Monterey Formation that accumulated in other California margin basins. Although more detritalrich and containing greater abundance of plagioclase and muscovite than more distal, outboard basins, a four-part compositional zonation is recognized in the fine-grained facies, similar to the stratigraphic succession of the Santa Barbara coastal area. In ascending stratigraphic order, these include a basal interbedded calcareous-siliceous zone, a phosphatic zone, a calcareous-siliceous zone, and an uppermost siliceous zone. To establish these zonations, 125 samples from five wells in a north-south transect across the western basin from East and West Beverly Hills, Inglewood, and Wilmington oil fields were analyzed for bulk chemical composition by XRF and quantitative mineralogy by XRD and FTIR. The mineralogic composition of the fine-grained detrital fraction makes use of geochemical equations for sedimentary components developed elsewhere unsuitable to the Los Angeles basin.</p>