The Problem of Scaling and Ways to Solve it in the Oilfields of Rosneft Oil Co.

Abstract

TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractRosneft oil production experience indicates that scaling is one of the most significant factors leading to a fall in the well production rate and to a shorter mean-time-between-failures of well pumps. Deposition monitoring indicates that the share of ECP failures due to scale varies from 12 to 25%.The various intensity of scaling in wells is related to a different saturation of produced waters with scale-forming ions, water-cut of the recovered fluid, and conditions of submersible well pump operation. In Rosneft wells, sulphate (barite) and carbonate (calcite) scales have been observed.To efficiently develop most oil fields, it is necessary to select scale inhibitors and preventing technologies taking into account peculiarities of individual wells. Analysis of ionic composition of reservoir and produced waters allowed to determine their saturation with scale-forming ions and to draw up recommendations as to the usage of chemicals, the effectiveness of which must be not lower than 90%, from a wide range of scale inhibitors.Pilot-field testing and a following large-scale application of scale preventing technologies, i.e. adding an inhibitor to the kill mud, permanent chemical feeding into the annular space of wells, application of submersible well feeding containers, and inhibitor injection into the water injected into the formation allowed to overcome the growing tendency of ECP failures due to scaling in the biggest oil production enterprise of Rosneft -OAO "Yuganskneftegas", and to increase the mean-time-between-failures of submersible pumping equipment by more than twice.