ESPs
Some thought should be given to addressing the problems arising from the use of ESPs in near horizontal sections where, unlike in vertical wells, debris is likely to accumulate across the well section. Hole cleaning procedures should be developed. The ESP design can be modified to create low tortuosity, high volume flow paths with large intake ports. Spiral fins and paddles to induce fluid rotation can be built into bypass clamps to prevent debris settlement at intake.
The inclusion of a permanent downhole flow meter system in the completion design should be considered. The meter can prove to be a valuable diagnostic tool during well commissioning and normal production operations. Real time data provided by the meter can help quickly diagnose situations where the pump has been operating in reverse rotation, where downhole recycling is occurring and where the well is under performing because of a pump suction blockage. The meter could prevent the premature failure of ESP units.
Long cable lengths in ESP completed ERD wells can lead to the build up of current harmonics in the in the drive/transformer/cable/motor system. This can result in overheating of the transformer system. The phenomenon has been observed but can be designed out by adding additional reactances to the system. The build up of air within the conductors of power cable during production operations immediately after ESP completion running can cause mechanical failure of the internals of wellhead penetrators leading to electrical failure of the completion. Special consideration should be given to controlling the rate of pressuring/depressuring of the production annulus containing the cable, and the design of the penetrator reviewed for a pressure release mechanism.
ESPs can be plugged by perforation debris and LCM.
Motor seal oil temperature and vibration monitoring devices are commercially available and should be considered where justified.
REFERENCES
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