Effect of hydrate-like particle concentration on gas-liquid-solid slug flow in horizontal pipelines

Gas hydrates are solid compounds that form under high-pressure and low-temperature conditions, posing a major threat to oil and gas operations because of their tendency to agglomerate and block pipelines. One mitigation strategy is to allow hydrates to form under controlled conditions, enabling their transport as a slurry within the liquid phase. However, limited research on how such particles affect key multiphase flow parameters has been conducted. This study investigates the influence of particle concentration on slug flow characteristics, a common flow regime in oil and gas production. Experiments using air–water and air–oil systems with model polyethylene particles mimicking hydrate density were performed in a flow loop. The test section was composed of 50-mm ID, 34-m long horizontal pipe. Four particle concentrations were tested: 0%, 5%, 10% and 20% v/v. Except under flow conditions near the stratified–slug transition line, which lead to long elongated bubbles and low slug frequencies, particles were effectively dispersed and transported in both the film and slug regions. The presence of particles had a weak effect on the slug flow topology – structure lengths, flow frequency, bubble velocity and phase fraction remained almost unchanged. This was attributed to the minimal impact of the particles on the thermophysical properties of the mixture. In contrast, particles significantly increased the pressure drops in the oil system because of a higher mixture density and a particle size comparable to the viscous sublayer, what affects the apparent viscosity. An empirical correlation for pressure drop prediction was proposed, achieving deviations of about 5% compared to experimental data