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

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

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

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>

<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.

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