Modern cable design focuses on material life and resistance to rapid gas decompression (RGD).
Flat ESP cable (CIS type KPPBP)
a - cable architecture; b - 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 bottomhole temperature (BHT):
- Polypropylene (PP): suitable for lower-temperature wells, typically up to 95 C (200 F). Cost-effective, but limited chemical resistance.
- EPDM (ethylene propylene diene monomer): industry standard for high-temperature service, rated up to about 205 C (400 F) or higher. Good electrical properties and flexibility.
To protect the insulation from well fluids and gases (H2S, CO2):
- Lead sheath: impermeable barrier against moisture and chemical attack. Common in high-gas wells to limit insulation swelling.
- Chemical barriers: specialized fluoropolymer tapes (for example Kapton or Tedlar) to extend EPDM life in aggressive fluids.
- Nitrile / EPDM jackets: mechanical bedding under the armor plus extra 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 to reduce pitting and corrosion.
- Monel: reserved for very sour service (high H2S).
- Flat cable: preferred for the motor lead extension (MLE) and for the whole string in slim-hole completions where the tubing-casing annulus is tight.
- Round cable: better mechanical balance; generally more robust as the main power cable in larger casing.
CIS marking KRBK is letter-true for a rubber-insulated round armored oil-submersible cable: K - cable, R - rubber insulation on the conductors, B - galvanized (or profiled) steel-tape armor, K - round cross-section. In the field the name is used loosely: people often say KRBK just because the cable is round, even though the R is rubber. Keep KRBK as the familiar mark; in plain English prefer round ESP / downhole power cable.
a - cable architecture; b - 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 (for example Kapton / Tedlar) wrap.
- Protective braid: impregnated synthetic yarn or high-strength bedding for internal friction reduction.
- Interlocking armor: profiled galvanized or stainless steel tape for crush and mechanical protection.