The North Sea Forties Field has been on production for five years. Reservoir performance predictions indicate that most wells will require artificial lift to maintain production at some part of their life. Of the artificial lift methods, electric submersible pumping appears to have considerable merit for use in the field. Electric submersible pumping requires minimal additional platform weight and power generation capacities.
This paper describes the approach taken in the first trial installation in Forties Alpha well FA 36. The completion design, choice and sizing of equipment is presented.
The electrical surface installation was designed as a prototype and not as a standard production unit, to give maximum information to assess areas for future development.
The effect of increased water cut on oil production levels in a typical Forties well with a 7" completion is shown in Figure 1. Although the graph indicates that the wells are able to flow naturally at water cuts up to approximately 50%, in practice, wells with water cuts greater than 20% have been found difficult to bring on stream after a shutdown.
Forties wells produce from 5000 to greater than 20000 STBOD. Wells with production rates up to 8000 STBOD are completed with 4 ½" completions, refer to figure 2 and those with production rates in excess of 8000 STBOD with 7"completions, refer to figure 3.