Composites as enabling technology in flow assurance

Aly, Samar (2020) Composites as enabling technology in flow assurance. Masters thesis, Memorial University of Newfoundland.

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Abstract

In oil and gas production, flow assurance guarantees a successful and economical flow of the fluids from the reservoir to a designated processing facility. Flow assurance is one of the biggest challenges that a pipeline designer faces, especially under deep water where the temperature is low, and the pressure is high. These deep-water conditions favor the formation of solid deposits, which leads to blocking the flow line, reducing oil production, and potentially shutting down the well. To avoid this problem, the flow line temperature must always be kept above the solid deposit formation temperature. This necessitates accurate analysis of the thermal properties of pipelines in order to choose the best material suitable under these harsh conditions. This thesis provides a quantitative comparison based on thermal characteristics for flow assurance purposes. It also provides a realistic comparison based on strength requirement imposed on risers in general. First, we present a comparison between two different solutions (analytical and approximate) to predict the temperature profile in the steady state flow case. This comparison is carried on a steel pipeline under different cases, which are obtained by varying the length of the pipeline and the flow rate. Based on the results of the comparison, the solution that meets the objectives of this thesis is identified. Then, the thesis focuses on the effect of using different materials in the pipeline. The thesis presents another comparison between traditional steel catenary risers (SCR) and Composite Catenary Risers (CCR) based on their thermal characteristics for flow assurance purposes. The comparison is based on predicting the fluid flow temperature along the pipeline to show which material will keep the temperature above the solid deposit formation temperature, which is set in this thesis to be 20℃. Nominal homogenized mechanical and heat transfer properties are used for composite and steel pipelines of the same thickness and diameter. The obtained results show that composite risers have enhanced thermal characteristics over its counterpart steel pipelines. To establish rational comparisons between SCR and CCR, other aspects of their performance must be considered. Performance aspects regarding material strength, expected life and minimal weight design constitute the most essential minimal set for these comparisons. Comprehensive investigations are conducted, and conclusions are extracted to quantify overall performance aspects of SCR and CCR. All the code used to run the experiments was implemented in MATLAB.

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