API RP 11S4:2002(2013) pdf download
API RP 11S4:2002(2013) pdf download.Recommended Practice for Sizing and Selection of Electric Submersible Pump Installations.
The number of starts and stops (cycles) during operation of an liSP determines the number of thermal cycles the seal chamber section must support. Illadder type seal chamber sections should be considered tr applications where frequent cycling is anticipated.
In some applications, bladder and labyrinth seal chamber sections arc used in tandem. In deviated wells, the bladder seal chamber section should be installed on top to prevent contamination of the labyrinth seal chamber motor oil. In s’ertical wells, the bladder seal chamber ‘c(ion may be installed on the bottom for increased protection of the bladder from chemical attack by the well fluid.
Seal chamber section designs are available that use multiple chambers in a single unit to achieve the functions of tandem seal chamber sections. In these designs, the criterion for arrangement of labyrinth and bladder chambers is the same as for tandem seal chamber sections.
8.2.6 Fluid Expansion Capacity
The etlective oil expansion capacity of a labyrinth seal chamber section will be reduced in deviated wells. Bladder- type seal chamber sections should be considered for wells with any deviated section over 30 degrees from vertical.
The required oil expansion capacity of the seal chamber section is a function of the total oil volume in the motor and seal chamber section and the maximum thermal cycle the unit experiences during installation and operation. Usually, the motor/seal chamber section assembly is at the lowest temperature during installation. The highest temperature will typically occur when the motor has reached operating temperature down hole. Provided with the thermal cycle, the manufacturer can select a seal chamber section with adequate oil expansion capacity.
Interchangeability of equipment offered by various manufacturers may be limited by flange and coupling incompatibility which may be overcome with the use of adapters. However, consideration should also be given to thrust requirements of the pump (both magnitude and direction) and oil volume requirements of the motor.
Actual motor loading should be considered when evaluating the required oil expansion capacity in the seal chamber section. The seal chamber section should be selected with sufficient oil capacity to accommodate the maximum probable motor load condition.
8.2.7 Seal Chamber Section 00 vs. Casing ID
The resultant diameter of the seal chamber section with the motor flat cable on one side should be smaller than the casing drit diameter to avoid damage when installing the equipment. Rekr to 6.2 for additional considerations.
8.2.8 Speed Effects
Operating at speeds other than 35(X) RPM will affect the seal chamber section performance. Generally, if you are operating from 30 — 70 Hi this is not a critical issue; however, the manufacturer should address any special bearing needs.
Operating an ESP system on a variable speed drive may cause increased motor temperature rise, which results in additional oil expansion. The seal chamber section nwst have adequate capacity to accommodate motor oil expansion at the highest anticipated operating speed. Shaft torque and thrust bearing capacity should also be checked at the highest operating speed since pump torque and thrust increase with speed. Mechanical shaft seals have a speed limit, which should not be exceeded. The ESP manufacturer can recommend safe operating speed ranges.
8.3 CHECKLIST
a. Determine seal chamber section 0l)’llangc size based on pump and motor requirements.
h. Determine expansion volume requirements based on motor HP and well conditions C primarily temperature).
c. Evaluate the required shaft torque capacity.
d. Determine approximate operating temperature.
e. Evaluate special conditions and operating temperanire and select elastomers, shaft seals, and material.
f. Calculate operating and no flow thrust loads and then select thrust bearing.
g. Select design style and configuration based on application and level of protection redundancy desired.
9 Select Cable (See API RPs 11 S5 and 11 S6)
Cable conductor size is selected based on the voltage and amperage requirements of the down hole motor, voltage losses over the length of the cable and clearance in the well. bore. In addition, cable insulation is chosen to survive in the well conditions and armor is selected to protect and contain the cable core.
