Mechanisms of Hydrate Blockage in Oil-water Dispersions Based on Flow Loop Experiments
Résumé
Hydrate formation is a threat to the safety of petroleum transport in flow lines due to the risk of plugging. In this work, conceptual mechanisms of hydrate formation and plugging in oil-water systems are proposed, based on flow loop tests at 30%, 50% and 80% water cut (water fraction). The experiments were conducted with Kerdane oil, water (with 30 g/L of NaCl) and natural gas at 75 bar and 4 °C. The employment of several instruments, such as acoustic emission, permittivity, and flowmeter, to cite a few, allowed identifying the different flow patterns until hydrate blockage and detecting the phase that carries the hydrates. A model based on density measurement is proposed to calculate the fraction of hydrates flowing locally. It was observed that there are local accumulations of most of the hydrates in a small portion of the flowing volume, which, together with deposition, ends up leading to plugging.
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