Investigation of Swirl Flows Applied to the Oil and Gas Industry

Abstract

Abstract The work presented in this paper is part of a larger Research Project which is aimed at finding solutions to problems associated with liquid loading, erosion at pipe bends due to sand particles and phase separation. The work uses computational fluid dynamics (CFD) to design solutions that can reduce or eliminate the aforementioned problems. Here, the results from CFD simulations of two-phase air and water flows are critically analyzed via comparison with the results from experiments carried out by Falcone et al. (2003) using the ANUMET* concept. The entire experimental setup is modeled within the CFD simulation and flow rates for water and air are taken from the data used for the experiments. Important variables such as pressure drop and fluid film thickness, which were monitored closely during the experiments, are obtained from the CFD simulations and compared with the experimental results. The results presented in this paper provide insights into the physics of two-phase swirl flows, identifying areas of research that still need to be addressed. Introduction Swirl flow (often referred to as vortex flow) is a fluid stream which has a rotational velocity as well as a linear velocity. Current research at Texas A&M University is studying the various applications of swirl flow to help mitigate particular problems in the oil and gas industry. Some of the swirl flow applications under investigation are: 1. Liquid Unloading in Gas Wells: Liquid loading occurs when the flowing gas is no longer capable of lifting the liquid to surface, which triggers liquid accumulation in the wellbore, resulting in additional hydrostatic pressure that impairs the gas inflow from the reservoir. If the reservoir pressure is low, the accumulated liquid may completely stop gas production. At higher reservoir pressures, liquid slugging or churning may occur in the production system, although this intermittent flow response may represent a temporary feature, until the well eventually dies. One solution is to generate swirling in the well in order to condition the flow and so reduce the energy losses and enable the well to lift liquids to surface. Fig.1 shows some tools that assist the unloading of gas wells and mitigate build up of stagnant fluids and paraffin in flow lines and gathering systems.