Combined Approach to Evaluate Hydrate Slurry Transport Properties through Wetting and Flow Experiments.

Abstract

A condensate oil system was evaluated with respect to its hydrate properties by two experimental methods, namely, the wetting index (WI) procedure and a flow loop called the wheel flow loop. The WI was used to initially indicate the efficiency of a gas hydrate antiagglomerant (AA), while the wheel flow loop was used for evaluating the transport properties of systems without and with AA. The results provide new insight into the effect of water cut and flow properties on the risk of hydrate plugging. The test case used in the study was a relevant field from the Vega gas condensate asset on the Norwegian continental shelf. This asset is currently producing using continuous monoethylene glycol (MEG) injection as a hydrate prevention philosophy. The wettability of the hydrate particles was determined for uninhibited, underinhibited (10% MEG), and AA-inhibited systems, and the results indicated favorable wettability of the AA-protected system by changing the emulsion inversion point to higher water cuts. Furthermore, the wettability data were then confirmed by flow tests utilizing SINTEF's wheel flow loop. Moreover, both uninhibited and underinhibited systems led to plugging upon hydrate formation, indicating the need for optimized AA concentrations for a given fluid system and water cut. The overall results show that the WI combined with the wheel flow loop or similar equipment is an effective method for better selection and description of the plugging potential and transport properties for gas hydrate systems.