2.5 Submersible Pump Major Components Rev Feb 2007

Copyright Rike Service, Inc., 2007 1

Submersible Pump Major Components



Transformer Bank

One or more transformers providing proper surface power


Motor Controller

One motor control panel housing the necessary switchgear and surface controls necessary for operation


Length of three-conductor special power transmission cable to link power from switchboard to motor


Motor

One or more (in tandem) electrical submersible three-phase two-pole constant speed induction motors


Seal Section

One motor to pump-bore fluid isolation section


Pump

One or more (in tandem) submersible centrifugal pumps


Submersible Lift Components


Typical Pump Stage


Pump Stages

Rotating Impeller

Fluid enters at eye near hub

Thrown into diffuser at impeller periphery

Pad where impeller rides on top of diffuser

Hub connects stages together


Pump Stages

Diffuser (Stationery)

Brings fluid back to eye of next stage

Provides bore for the impeller hubs

Pumped fluid provides lubrication, impeller to diffuser


Pump StagesImpeller is pressure balanced at peak efficiency

Overload causes upthrust wear

Underload causes downthrust wear

Usually can operate at 75% to 125% of peak successfully

Volume proportional to speed (usually 3475 RPM)


Pump Stages

Head/stage in ft =

U2 (velocity at periphery, fps)2g (gravity constant)

Head is independent of fluid density

Output press = H x S x 0.433


Pump Stages

Stages added in series to provide required head

Head must cover vertical lift, friction pressure, and surface back pressure

Volumes of 20 BPD to 25,000 BPD and higher


Pump Stages

Sizing must be correct

Over or under capacity shortens thrust bearing life

Pumping off causes cable or motor failure due to heat


Motor

Two pole, three phase, squirrel cage, induction type

3475 RPM on 60 Hertz 230 to 5,000 volts 12 to 110 amps Not synchronous, slip

increases with load only slightly

Efficiency, 80% to 90%


Motor

Cooled by passage of produced fluid by external case

Requires velocity of about 1 fps

Viscosity and density changes can affect cooling


MotorPressure balanced to the well fluids Lubricating oil inside motor Isolation achieved with

dense lubricant at bottom of U-tube

Well fluids contact dense lubricant on one side of U-tube

Provides for expansion of lubricant when hot


Motor

Sized in 4" to 7" diameter

BHP = Q x H x Sp. Gr.

Eff. x 3960


Protector or Seal Section Connects pump to motor,

both outer housing and drive shaft

Houses the pump thrust bearing

Seals power end of motor housing from wellbore fluids and provides pressure balance or communication

Provides volume necessary for oil expansion at operating temperature


Protector or Seal Section:Important Requirements

Clearance in the casing to allow flat cable operating temperature

All thrust load must be transmitted to thrust bearing

Thrust bearing requires good alignment

Oil viscosity very important to thrust bearing life

Vibration and misalignment will destroy oil film


Cable Characteristics

Copper or Aluminum Round stranded cable in

major portion Flat cable where clearances

are small Resistance drops voltage

according to length


Sizing Cable

Chosen for current carrying ablity: Example, No. 1 Cu carries up to 110 amp

Ohms per 1,000 ft. indicates voltage drop, E = 1R

Insulation indicative of voltage service available

Voltage drop/Amp/1,000 ft. range: 0.3 to 4.0 +


Insulation and Armor

Temperature seriously affects some insulation

Armor affected by abrasion and corrosive fluids

Some operators attribute more than half of submersible pump problems to the cable


Key Components of Controller

Motor StarterOverload Breaker (fast acting)

Need only ½ second forhigh current start up



Underload Breaker Important because of need

for cooling motor Usually has automatic restart



Manual disconnect Time delayRecording ammeter

(important diagnostic tool) Fuses for short circuit

protection (fast acting) Sometimes includes surface

read out of BHP and BHT



External Controls Tank hi-lo switches Line pressure switch



Good settings and proper maintenance of controls are often the key to successful or unsuccessful operation

2.5 Submersible Pump Major Components Rev Feb 2007

Documents

copyright

seal section

key components

fast acting

cable

motor

eye

length