Experimental Study of Single-Phase and Two-Phase Water-in-Crude-Oil Dispersed Flow Wax Deposition in a Mini Pilot-Scale Flow Loop

Wax deposition tests under single-phase and two-phase dispersed water-in-oil at 16 and 35% water cut (WC) were conducted in a mini pilot-scale flow loop by using South Pelto crude oil. The initial inner wall temperature ((T) over bar (w,ini)) and the bulk fluid temperature (T-b) were controlled to be 85-87 degrees F and 105-107 degrees F, respectively, throughout the experimental program. The initial Reynolds number (Re-ini) of tests conducted in rectangular (TS1) and circular (TS2) test sections was in the range of 400-4300 and 1000-5300, respectively. A high temperature gas chromatograph with flame ionization detector (HTGC-FID) and a differential scanning calorimeter (DSC) were used to analyze wax deposits. The results revealed that the 16 and 35% water cut tests yielded deposits containing only a trace amount of water (less than 2% w/w). The crossover behavior of the thickness versus time trends for different flow conditions was observed. The initial thickness growth rate increases with the flow rate. After the crossover period ended, the deposit formed under a lower flow rate condition had a higher thickness. In this experimental program, velocity, wall shear stress, Reynolds number, and heat transfer coefficient are coupled together. The initial heat transfer coefficient was found to correlate to the 48 h deposit thickness best compared to the initial wall shear stress, the initial Reynolds number, and the initial velocity. The effect of shear on the deposit composition was observed.