As the main reservoirs get depleted, operators are looking increasingly into the satellite fields that hold oil but in quantities that would not justify building a dedicated platform.
Consequently, methods of extracting the oil from these reservoirs by using existing facilities have been investigated. One of the most viable options is to utilize the existing mother platforms to accommodate all the topside electrical equipment, and extend cables up to a distance of 30 kms to the wellheads.
The purpose of this paper is to illustrate the work done by Reda in developing a computer software model to simulate the complete electrical system, and thus predict any problems that might be encountered in a real system. The model was verified by practical data obtained from tests conducted in the Reda, Inverurie (Scotland) and Reda Bartlesville (USA) facilities.
The program was designed to simulate various variable speed drive (VSD) power sources and model the effects of different lengths of cable to determine what combinations of VSD, cable parameters and downhole motor operating conditions would have on the total harmonic distortion.
With the cost of intervention of an electrical submersible pump (ESP) reaching 5.6 million US dollars, weather permitting, and reliability still being an issue, operators are interested in ensuring that all possible scenarios that could be encountered are investigated in advance of installation.
One of the main concerns are the ever increasing levels of electrical Harmonics in the system due to the nature of the electrical systems.
Before we progress further it is worthwhile mentioning the four main factors that determine the life of the motor. These are:-
The ambient temperature of the produced fluid.
The composition of the produced fluid in terms of its capacity to carry heat away.
The velocity of the produced fluid past the motor.
The level of losses within the motor.
It is clear that temperature is a critical factor as it has direct impact on the insulation, and it is generally accepted that the insulating material is an exponential function of winding temperature. P. 475^
