Testing, Characterization, And Analysis Of Class F Fly Ash Geopolymers Under Oilfield Testing Conditions

Abstract

The oil and gas industry relies heavily on Ordinary Portland Cement (OPC) for wellbore integrity, but the limitations of OPC in extreme environments such as high temperatures and pressures have necessitated the exploration of alternative materials. This dissertation investigates the potential of fly ash-based geopolymers as a sustainable alternative to OPC, focusing on their unconfined compressive strength (UCS) and compatibility with American Petroleum Institute (API) cement testing standards. Geopolymers are an inorganic polymer resulting from the reaction of aluminosilicate material and an alkali solution, typically comprised of potassium or sodium and hydroxides The research begins with an overview of the environmental impact of traditional cement production and the necessity for robust wellbore materials. It details the standard testing methods for OPC, including preparation, curing, and mechanical testing procedures, and extends these methods to geopolymers. The effects of various curing conditions and chemical compositions on the UCS of geopolymers are evaluated through a series of experiments. Results demonstrate significant variability in geopolymer performance, which is attributed to the inherent differences in fly ash composition and the lack of standardized testing protocols. Enhanced investigation techniques, such as Nuclear Magnetic Resonance (NMR) and Scanning Electron Microscopy (SEM), provide deeper insights into the microstructural properties of geopolymers and their correlation with mechanical performance. A comparative analysis of geopolymers and traditional API cements under similar conditions reveals that while geopolymers offer potential benefits, their inconsistent performance poses challenges for widespread adoption. The dissertation advocates for the development of standardized testing procedures specific to geopolymers to ensure reliable performance metrics. It explores the implications of using geopolymers in geothermal well completions, suggesting that with further research and standardization, geopolymers could become a viable alternative in high-temperature applications. The study concludes with a summary of vii findings and recommendations for future research, emphasizing the need for a comprehensive understanding of geopolymer chemistry and the establishment of industry-wide standards to facilitate their adoption in oil and gas operations.