Energy & Fuels, Vol.30, No.6, 4570-4582, 2016
Study on Two-Phase Oil-Water Gelling Deposition Behavior in Low Temperature Transportation
The waxy crudes gelling and the wax depositing on the inner walls of crude oil pipelines present a costly problem in low-temperature transportation processes. This study focuses on a physical understanding of the gelling deposition during flow of two-phase oil water in the pipelines. A method for evaluating the gelation characteristic of two-phase oil water is established, and the effect of emulsified water on gelation is discussed. As the physical properties description, the two-phase diffusion coefficient is found to be a strong function of the water cut. The potential models developed from single-phase flow wax deposition models are proposed spontaneously, and the deposition behavior of two-phase flow in pipelines is predicted under a range of flow conditions in low-temperature transportation. The predictions show that the gelling deposition rate of two-phase oil water flow is closely related to the pipe flow temperature, external temperature, water cut, and flow rate. The mechanisms of kinetic resistance for diffusion and gelation nucleation related to emulsification are non-negligible under the low-temperature condition. The prediction models are then verified by deposition experiments that are conducted in the laboratory flow loop. This study is not only beneficial to provide a robust and rigorous way to predict two-phase oil water gelling deposition under the condition of the low-temperature transportation but also significant to well understand the deposition process in oil water flow. Besides, the study further accelerates the simplification and optimization of petroleum industry production engineering as well.