| Three-phase gas-oil-water slug flow evolution in hilly-terrain pipelines was studied experimentally and theoretically. An experimental facility was designed and constructed to observe the changes in slug flow characteristics through hilly-terrain pipelines. The constructed facility was a 69-m long, 50.8-mm ID outdoor facility with +/-5° inclination angle for a valley configuration. In-house built laser sensors were modified for the outdoor facility. Capacitance sensors were also built to measure slug flow characteristics. The superficial liquid and gas velocities were varied from 0.2 to 1 m/s and from 0.1 to 5 m/s, respectively. Three-phase gas-oil-water flow tests with 20, 40, 60 and 80% water cuts were conducted. Gas-oil-water slug flow was characterized throughout the acquisition and analysis of high quality experimental data was performed for pressure drop, average liquid holdup, phase distributions and slug characteristics. A total of 108 tests were completed.;Steady-state three-phase flow patterns for slug flow were identified as a reference to slug flow in hilly-terrain pipeline. Three-phase slug flow evolution along the hilly-terrain section was categorized based on slug dissipation, initiation and growth at different water cuts. The experimental analysis revealed that water cut does not affect the flow categories. For low gas and liquid flow rates, no water cut effect on pressure gradient, slug frequency and slug length could be observed. From moderate to high flow rates, differences in the experimental parameters were observed due to change in oil-water dispersion characteristics.;A two-phase slug dissipation model was modified and the results are compared with experimental slug to slug unit length ratio. The two-phase model predicted the slug flow evolution in the hilly-terrain section. Experimental pressure gradients, average total liquid and water holdups, slug frequency and slug length data were also compared with a commercial transient multiphase simulator, OLGA(TM). Predicted parameters matched well with experimental results. Thus, the models' comparisons validated that the effect of water cut on slug flow evolution in hilly-terrain pipelines was limited to its effect on dispersion characteristics. |
