D. Tijunelis & Robert Wargin, Borg-Warner Corp.
Whenever large volumes of oil-well fluid have to be lifted, the submersible pump-motor system is the most logical artificial lift system to use. The submersible pump will operate efficiently above 300 barrels per day. The submersible pumping system is composed of the motor, seal, pump, and other hardware, as well as a long length of power cable. The most obvious unique feature of a submersible system is its geometry to fit a narrow hole and its reliability to last under adverse environmental conditions without convenient access for repair or inspection. Generally speaking, cables are neither the most complex element in a submersible pumping system nor the most delicate or susceptible to damage. The majority of cables in application today last many years with a minimum of repair requirement. Nevertheless when cable damage occurs, it becomes a significant problem. Anytime cable damage occurs, the whole system has to be shut down, pump and motor pulled, and a very simple repair done, with again a feeling of having to go through all that trouble and cost for a seemingly insignificant reason. Because of this feature of the application, the process of selection of the submersible power cable needs to be understood. Historically, cables were initially made by manufacturers of general purpose cables for mining, communication, heavy machinery, and building industries. The manufacture of cables has been divorced from the oil-field production equipment industry and out of touch with the oil-field requirements. There has been little guidance, specialized technical know-how, or business incentive for the cable manufacturers to carry on intensive research and development on cable improvements for oil-well application. Submersible equipment manufacturers began to test and specify oil-resistant power cable construction in the late 1950"s. In the 1960's the manufacturers of Centrilift submersible oil well pump equipment contracted their corporate research center to undertake longterm development of submersible power cables more specifically suited to oil-well applications. Through their initiative and that of the centralized research team at Borg-Warner in cooperation with key material suppliers as well as cable manufacturers, and with field testing by most major oil companies, new cables are being developed and an extensive amount of knowledge is being generated about cable requirements, material performance, field handling practices, splicing, etc. The purpose of this paper is to provide those using or considering the use of submersible pumping systems information about the selection of cable and thus, in an objective manner, to enhance the reliability of submersible-pump systems and encourage their application.