ANALYSIS OF PRESSURE WAVE PROPAGATION IN MULTIPHASE FLOW IN OIL PRODUCTION LINES AND NUMERICAL MODELING OF PROCESS

Date

2024-7-25

Author

Özdemir, Rabia Tuğçe

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Pressure propagation in pipelines plays a critical role in analyzing fluid flow behavior and optimizing the transportation of multiphase flows in various industries, including the oil and gas sector. Understanding this process in these multiphase flows offers valuable insights into their composition, phase distribution, and flow regime, enabling efficient and safe pipeline operations. This study offers a comprehensive examination of pressure propagation in pipelines, a particularly significant phenomenon in the transportation of multiphase flows within the oil and gas industry. The core of this research lies in a method developed to determine the speed of pressure waves in multiphase fluid flows along oil production lines. Data were collected during a testing operation conducted on an offshore production platform in the North Sea. The method emerged from detailed observations of pressure propagations along production lines during normal operational activities. Pressure signals, potentially generated by such activities or by the transient dynamics inherent to multiphase flow, were recorded at two distinct locations along the production line. These signals were then subjected to cross-correlation analysis to calculate the flight time of the signal, thereby determining the speed of the pressure waves. The measured speed of pressure waves in the multiphase fluid was compared against two established empirical models—the Wood model and the Dong and Gudmundsson model—both of which calculate the speed of sound based on fluid properties, gas-oil ratio (GOR), water cut, pressure, and temperature. Additionally, the measurements were compared with simulation results from a transient multiphase flow simulator, utilizing the same PVT properties. The analysis revealed that the Wood model tends to overestimate the speed of sound, particularly at higher pressures. In contrast, the Dong and Gudmundsson model offers closer approximations to the measured pressure wave propagation speed. Moreover, the transient flow simulator strongly correlated with the measured data across almost the entire pressure range, reinforcing its reliability. In addition to the empirical measurements and comparisons with established models, this study also incorporates numerical modeling to further investigate the effects of pressure wave propagation in pipelines. Both 1-D and 2-D numerical models were employed to analyze how pressure waves behave within the pipeline system. The results from these models revealed that the speed of sound significantly impacts the amplitude of a pressure pulse, particularly when the velocity changes gradually or when the pulse encounters a discontinuity. Specifically, when a pressure pulse moves from a low-speed region to a high-speed region, it results in a transmitted pulse with higher pressure. While these effects were detectable in the 2-D model, the complexity of the model posed challenges in calculating the propagation speed of pressure waves as effectively as in the 1-D model. The 1-D model, with its simplified assumptions, allowed for a more straightforward calculation of wave propagation speed, whereas the 2-D model's complexity necessitated a more detailed analysis.

Subject Keywords

Çoklu akış, Basınç dalgalarının yayılması, Çapraz korelasyon

URI

https://hdl.handle.net/11511/110557

Collections

Graduate School of Natural and Applied Sciences, Thesis