Abstract
The flow assurance aspects of all subsea projects have a major contribution to the pipe design, field layout, choice of lifting equipment (subsea-pump or air lift), power requirement and system operability.
The context of Deep-Sea Mining pushes beyond their validation limits the existing flow model of particle transportation due to the transient flow of large particle sizes in a small diameter riser evolving in a wave shape. In order to correctly assess the pressure drop in the deep-sea mining riser using a pump lift (Solid-Liquid two-phase flow), TECHNIP has developed a new transient flow assurance model named FASST – Flow Assurance Simulation for Slurry Transportation. This software enables numerous design calculations and riser live monitoring.
This publication establishes the limitations to date of the existing large particle transportation theories before describing the novelties implemented into FASST: a lagrangian tracking of the particles coupled to classical slurry pressure drop calculations for Liquid-Solid two phase flow.
In order to extend FASST applicability, some of the numerical aspects will be highlighted to demonstrate the capacity of the model to calculate solids transportation in "real-time".
The model was validated against both small scale and large scale tests performed at GIW in Augusta. Theoretical results proved to be in agreement with experimental results allowing a very good confidence in the FASST prediction of transient flow regimes.
