Influence of pipeline inclination on gas-liquid conveying of sand particles

Abstract

The understanding of sand particle transport by multiphase fluid flows in near horizontal pipelines is of considerable importance for the drilling of horizontal and inclined hydrocarbon production wells, topside process facilities, infield pipelines, and trunk lines. Previous studies on two phase fluid conveying of sand particles in pipelines have made significant contributions to the understanding of multiphase flow patterns, pressure drop and particle transport rate in horizontal pipelines. However, due to the complexity of the flow structure resulting from gas-liquid-sand interactions, the mechanisms responsible for bed-load transport flow for two phase fluid flow conveying of sand particles have not been extensively studied in inclined pipelines. This thesis presents an experimental investigation of sand conveying from a stationary flatbed inside a pipe through hydraulic and two phase liquid-gas flows, a function of the fluids flow rates, pipeline orientation (α = 0° and +3.6°), and sand bed thickness. The characteristics of sand particle transportation by saltation, and both the sand dune formation process and morphology are visualized using digital photography of a transparent Plexiglas pipeline. The pipeline inclination is found to have a significant influence on sand dune dynamics (i.e. dune conveying velocity), as well as dune topology (i.e. dune pitch and characteristic angle). Sand particle conveying in an upward inclined pipeline through hydraulic fluid flow results in an increase of the critical lifting velocity to overcome the gravitational force on sand particles. However, sand particle conveying through two phase liquid-gas flow results in movement of sand particles in the upstream direction of the liquid film region with particles collision occurring within the liquid slug zone. The water component of the two phase conveying flow was found to be 40% to 60% lower than the hydraulic conveying flow rate. In addition injecting air to produce an intermittent flow (e.g. elongated bubble, plug, and slug flow) can significantly improve the sand conveying rate, which constitutes an improved sand mitigation strategy. Thus, introducing gas lift for hydrocarbon recovery is of considerable value for enhancing the efficiency of sand conveying in hydrocarbon production facilities.

Date of Award	2013
Original language	American English