Computational fluid dynamics modelling of multi-phase flow transition in presence of solid particles.

Multi-phase flow is the type of flow common in the oil and gas industry, as oil reservoirs contain mixtures of oil, gas and water with sand particles from sandstone reservoirs. Accurate design of oil and gas production equipment greatly depends on detailed understanding of this flow phenomena. Previously, multi-phase studies relied upon empirical correlation and mechanistic equations developed from experimental data, but these approaches have limitations because of limited experimental data and underlying simplified assumptions. Thus, these methods cannot be used for complex flow situations often encountered in mature oil and gas fields. Hence, the lack of scalability of the existing classical empirical correlations and mechanistic models has called for a high-fidelity modelling method. In this research, a computational fluid dynamics (CFD) method is used to investigate gas-liquid and gas-liquid-solid multi-phase flow in a vertical pipe. A hybrid model, the multi-fluid Euler-Euler and Euler-Euler-Euler model with interfacial area transport equation (IATE), were used to simulate the flow regime spectrum in a large diameter vertical pipe. The hybrid model could simulate the mean gas volume fractions and bubble size changes as a function of fluid rate. The predicted gas volume fractions were benchmarked against experimental data and were in agreement. Changes in the gas flow rates were seen to generate flow transitions from bubble to annular flow, which compared favourably with appropriate literature across the vertical flow regime spectrum. However, sand particle inclusion in the flow scheme were seen to change the flow dynamics, which were found to be greatly dependent on the particle concentration. Solid particle concentrations were seen as the major deposition influencer. The results of this research elucidate the regime transition in a three-phase gas-liquid-solid flow scheme of a typical production well, and is viable for well-production optimisation and completion design in large-diameter vertical pipes