Method of Periodic Operation Mode Forecasting

Abstract

This paper addresses the control of oil wells equipped with electric centrifugal pumps (ESPs) running in a periodic operation mode, a mode that is spreading as fields are depleted and new fields with poor reservoir features, such as the Bazhenov shale suites, are placed under production. Such wells have low flowrates (less than 15 m3/d) at dynamic fluid levels over 2,000 m, and exploiting them with low-capacity ESPs reduces the pumps' mean time between failures. The aim is to improve the efficiency of ESP control in the auto-reclosing mode and to simplify routine work for field production engineers. Using field data from the North Labatyugansk oil field, the author shows that a previous pump failed because its cable extension was damaged by pump temperatures above the 230 °C working limit, and notes the lack of an adequate theoretical basis for designing periodic operation. A step-by-step calculation method is proposed: the suction pressure that keeps the pump temperature below the permissible level is determined, daily rundown and accumulation times are derived from the well flowrate and optimum pump delivery, and a heat-balance equation of the pump gives a safe rundown time per cycle, free of salt deposition, and the number of cycles per day. Because the manual calculation is cumbersome, the author suggests programming the procedure for engineers' computers.

Abstract prepared by the editorial office from the full text of the article; the authors did not supply one.