Flow testing methods to detect and characterize partial blockages in looped subsea flowlines

Looping subsea flowlines is one method being utilized for flow assurance. L ooping allows the possibility of circulating chemicals and/or tools to reme diate partial flowline blockages due to wax, paraffins, asphaltenes, hydrat es, sand and scale. This study considers if flow testing cml provide an a p riori knowledge of the presence and/or size of the partial blockage before remedial action is taken. The techniques developed are for single-phase liq uid flow and can be applied during circulation operations in looped flowlin es or in single-phase oil transportation lines. Using these models, a block age map is created to indicate what size of blockage can be detected and wh at size of blockage can be characterized as to length and diameter of the r estriction. Field-scale verification was obtained by placing fixed length a nd diameter partial blockages in the 9460-ft LSU flowloop (3.64-in. i.d.). Tests were conducted,with liquid rates to II bpm (15,840 bbl/day) and press ures to 4000 psia.