Review of Oil–Water Flow Characteristics of Emptying by Water Displacing Oil in Mobile Pipelines

Water displacing oil is one of the main emptying methods for mobile pipelines. It has advantages being a simple process and highly safe. At present, determination water scheme pipelines based on oil–oil alternating transport theory product However, insolubility phase results in great difference between flow characteristics pipeline. In addition, due to effect buoyancy, gathers at high point pipeline forms liquid accumulation, which difficult carry away by flow, resulting low efficiency The essence an oil–water two-phase unsteady displacement involving liquid–liquid carrying oil. Aiming such problems, domestic foreign scholars have carried out large number theoretical experimental studies, established mixing model relationship macroscopic quantity (flow pattern, pressure drop content) microscopic (local field droplet dispersion etc.) under each type, explored influence diameter, velocity, inclination angle other parameters capacity accumulation. On this basis, paper analyzes shortcomings current research from three aspects: formation mechanism mixture, immiscible fluids Five future directions are proposed, including interface morphology layered local dual continuous interface, distribution dispersed mixture accumulation topographic relief pipes.