Abstract
A transient mathematical model based on continuity equations for liquid and gas phases, with a momentum equation for the mixture, was developed, and numerical solutions and simulations corresponding to severe slugging in pipeline-riser system were presented, and the results were compared with the experimental data to verify the mathematical model. In numerical solutions, backward Euler schemes were adopted as predictors and trapezoidal methods were used as correctors. Variable time steps were employed for higher computational efficiency and accuracy in the integration. Experiments of severe slugging characteristics were performed, and the simulation results of the cycle periods and bottom pressure were compared with experimental values. Finally, the calculation results of detailed characteristics were analyzed thoroughly. The results show that the developed mathematical model can accurately predict the cycle time and the detailed characteristics of severe slugging. Under the experimental conditions, the liquid slug length can reach 1.6 times the height of the riser, and the maximum instantaneous gas velocity of outlet is 50 times the inlet gas velocity, and the maximum instantaneous liquid velocity of outlet is 28 times the inlet liquid velocity, having important implications for the hazard assessment of severe slugging.
Highlights
In the offshore and deep water oil and gas development, multiphase transportation is more economic as a transportation way
It shows that the simulation results agree with the experimental results essentially
The laboratory experiment was implemented and the experimental results were compared with the simulation results to verify the accuracy of the mathematical model
Summary
In the offshore and deep water oil and gas development, multiphase transportation is more economic as a transportation way. Balino et al [9, 10] presented a mathematical model considering continuity equations for liquid and gas Chinese Journal of Engineering phases, with a simplified momentum equation for the mixture, neglecting inertia, and considering inertia, respectively, and simulated the transient characteristics of severe slugging. A computational fluid dynamics (CFD) method is proposed for numerically simulating the gas-liquid severe slugging in a pipeline-riser system. Numerical simulation methods are mainly divided into two categories: (1) numerical simulation of the whole flow field based on CFD; (2) simplified one-dimensional transient model. The former method’s advantage is that the detailed characteristic parameters of flow field and the liquid-gas interfaces can be described precisely. The simulation of the liquid fallback is added to improve the accuracy of simulations of the flowing characteristics and cycle period of severe slugging
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