ESP Downhole Power Cables are designed to transmit electrical power to the motor under extreme temperature, pressure, and corrosive conditions.
Modern cable design focuses on material longevity and resistance to rapid gas decompression (RGD).
Flat ESP Cable (KPPBP) Construction
а - Cable Architecture; б - Protective Armor profile.
- Copper Conductor: High-conductivity solid or stranded copper.
- Insulation: High-temperature EPDM or Polypropylene (PP) compound.
- Protective Jacket: Chemical-resistant Lead Sheath or Nitrile rubber barrier.
- Bedding Tape: High-strength Fluoropolymer or Glass-fiber tape.
- Oil-resistant Wrap: Specialized oil-resistant synthetic tape for mechanical integrity.
- Protective Braid: Impregnated cotton or synthetic yarn for internal friction reduction.
- Interlocking Armor: Galvanized or Stainless steel tape for crush protection.
The choice of insulation depends primarily on the bottomhole temperature (BHT):
- Polypropylene (PP): Suitable for low-temperature wells, typically up to 95°C (200°F). It is cost-effective but has limited chemical resistance.
- EPDM (Ethylene Propylene Diene Monomer): The industry standard for high-temperature applications, rated up to 205°C (400°F) or higher. It offers excellent electrical properties and flexibility.
To protect the insulation from well fluids and gases (H2S, CO2):
- Lead Sheath: Provides an impermeable barrier against moisture and chemical attack. Essential for high-gas wells to prevent insulation swelling.
- Chemical Barriers: Specialized fluoropolymer tapes (like Kapton or Tedlar) are used to enhance the life of EPDM in aggressive environments.
- Nitrile/EPDM Jackets: Provide mechanical bedding for the armor and additional chemical protection.
The outer armor protects the cable from mechanical damage during Running-In-Hole (RIH):
- Galvanized Steel: Standard for non-corrosive environments.
- Stainless Steel: Used in wells with high CO2 concentrations to prevent pitting and corrosion.
- Monel: Reserved for extremely sour environments (high H2S).
- Flat Cable: Preferred for the Motor Lead Extension (MLE) and for the entire string in "slim-hole" completions where space between the tubing and casing is limited.
- Round Cable: Offers better mechanical balance and is generally more robust for the main power line in larger casing sizes.
Round ESP Cable (KRBK) Construction
а — Cable Architecture; б — Protective Armor profile.
- Copper Conductor: Solid or stranded high-conductivity copper core.
- Insulation: High-temperature EPDM (Ethylene Propylene Diene Monomer) or Polypropylene compound.
- Chemical Barrier: Lead Sheath or Nitrile-based protective jacket for hydrocarbon resistance.
- Bedding Tapes: Double-layer synthetic or fluoropolymer (e.g., Kapton/Tedlar) protective wrapping.
- Protective Braid: Impregnated synthetic yarn or high-strength bedding for internal friction reduction.
- Interlocking Armor: Profiled galvanized or stainless steel tape for high crush and mechanical protection.