Experimental and Visual Simulation of Gravel Packing in Horizontal and Highly Deviated Wells

Abstract The gravel packing process in horizontal or highly deviated wells involves the solid-liquid two-phase flow and the sand-bed migration under complicated conditions, in which the sand carrier fluid filtrates into the formation and the mass exchange occurs between the fluid in screen-washpipe annulus and the fluid in casing-screen annulus. One of the key problems in gravel packing is to predict the α wave sand-bed equilibrium height to simulate the gravel packing process and optimize operation parameters. In this paper, a full-scale simulation equipment for internal circulation gravel packing in horizontal wells is utilized for the study of the effects of screen offset, flow rate, and sand concentration on the α wave sand-bed equilibrium height. The comparison is made among the results using three empirical equations to calculate the equilibrium flow rate. Based on Gruesbeck model, a more accurate calculation method of the equilibrium sand-bed height is developed. Then, the mass and momentum conservation equations of the gravel and sand carrier fluid of two-phase flow in casing-screen annulus and single-phase flow in screen-washpipe annulus and the flow coupled equations of these two flow systems are established. A mathematic gravel-packing model for horizontal and highly deviated wells is thus obtained. The solution of the model can lead to the development of gravel-packing simulator software package, which can be used to visually simulate the gravel packing process. The characterization of the gravel packing process and the variation of each dynamic parameter are also analyzed.