Simulación Numérica-Térmica De La Línea De Flujo Submarina Del Campo Amistad

Abstract

In this work, the thermodynamic and heat transfer analysis was developed for the undersea flowlines, AMS-10 and AMS-11, from the wellhead to the riser of the offshore platform of the Amistad Field. The heat losses of the production fluid were determined by numerical methods of the computational fluid dynamics (CFD), using the ANSYS-CFX software with academic license. The thermodynamic analysis of the fluid was carried out based on the thermal and mechanical properties of the phases, together with the study of the equilibrium curves of precipitation of methane hydrates, obtained through five analytical correlations, an Industrial Process Simulator and a commercial software named Hydrate-Plus; in addition, the pressure-temperature diagram of the gas was determined. The thermal gradient of the flowlines was presented as result of the heat transfer analysis, which shows the critical points where the gas reaches its lowest temperature, i.e. the temperature of the submarine stream. The critical point for the AMS-10 line was determined at 5560 [ft] and for the AMS-11 line, at 5300 [ft]. From the analysis of these points, two scenarios of precipitation risk were established during the gas transportation; and it was shown that the probability strictly depends on the operating conditions. To complete the study, it was concluded that there exists hydrate formation in both pipelines inside the worst scenario; while in the best scenario the operating pressure must exceed 1800 [Psia] for precipitation to occur. The results of the CFD simulation were validated by a one-dimensional analytical correlation of heat transfer and with data from simulations of the Amistad Field. Additionally, the effects of the hydrodynamic phenomenon caused by the multiphase flow were studied, determining a Mist flow pattern, where the liquid phase of the fluid is dispersed inside the gas in form of droplets of water. The study of the pressure drop was carried out by means of the Beggs & Brill correlation (1973) and validated with the results of the open source software DWSIM and the Simulator of Industrial Processes.