The problems of constant duty operation of electric centrifugal pump units in marginal wells are considered. The causes of electric submersible pumps (ESP) units starvation are analyzed. The necessity of applying new technologies and technical solutions is shown. One of the rational ways is to use additional equipment: control stations with a frequency converter and AC electric motors for bringing wells on a stable production. The methods of bringing marginal wells (with production rate of less than 20 m3/day) and methods for selecting electric centrifugal pump units with AC electric motors are considered.
It is shown that the technique of maintaining a given frequency of the ESP unit does not always allow the well to be brought to a stable production, because the pump starvation occurred from insufficient thrust of the electric submersible installation.
The technique for calculating the running current, corresponding to the technological parameters of the well operation, on the basis of head and flow rate of ESP units is presented. The application of this technique allows to reduce the time of bringing the well to a stable production and to increase oil output.
If the electric submersible unit fails, it is suggested to use a technique, developed on the basis of a change in the pump head and flow rate depending on the engine shaft speed. The ESP units, supplied with the AC electric motor, have a head margin, which allows marginal wells operation using frequency regulation. According to this technique, knowing the inflow rate at a certain dynamic level, we can determine the type of pump to be lowered into the well. An example of equipment selection for three types of ESP units, equipped with AC electric motors, is given.
The possibility of applying the proposed methods is confirmed by the results of the tests, carried out at the Oil and Gas Production Department Komsomolskneft fields.References
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