Abstract

MARQUEZ, Richard  and  PRADO, Mauricio. Predicting downhole natural separation efficiency by a correlation. Rev. Téc. Ing. Univ. Zulia [online]. 2007, vol.30, n.Especial, pp.336-343. ISSN 0254-0770.

Quantifying the downhole natural separation efficiency will help to minimize the presence of free gas at pump intake and to avoid certain operational problems, such as: gas lock, surging, cavitation, over heat, among others, in systems of artificial lift by pumps. In the last few years, the University of Tulsa Artificial Lift Projects (TUALP) experimental facilities were used to obtain important experimental data on natural separation. This data has allowed the development of simplified models such as Alhanati [1] and Serrano [9]. Even though previous models have been able to estimate the natural separation efficiency, both models never considered the effect of important variables as the slip velocity in the radial direction and the geometric characteristic of the bottomhole completion. This paper presents a new correlation obtained from TUALP experimental data. This work is different than previous simplified models since it considers the drag effect in the radial direction. This new model represents a simple and reliable tool, which allows a robust estimate of the natural separation efficiency with a higher accuracy.

Keywords : Natural separation; free gas; slip velocity; artificial lift.