Comprehensive protection of subsurface equipment

Using electrochemical inhibition

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Scaling Issue

Scaling Issue

(scale buildup) on working surfaces of subsurface equipment always shadows the oil production process.

ECP Body Scaling

  • The system heat exchange is disturbed, the operative parts of the pump get overheated, and fail
  • Most of scale buildups are primarily composed by calcium carbonate CaCO₃, calcium sulphate CaSO₄, barium sulphate BaSO₄ mixed with corrosion products and grogs
  • The scaling process comprises three major stages:
    • Ion pairing
    • Ion pairs merging to form microcrystals (crystallization seeds)
    • Crystal growth and aggregation

  • Involvement of M²⁺ ions causes calcium carbonate and magnesium carbonate to sediment as acicular aragonite crystals (the crystalline CaCO₃ modification) which have low surface adhesion, and tend to come off due to dy-namic ambient effects (self-cleaning)

Composite Coating

Effect and Action Mechanism

  • The coating allows to extend service life of submersible centrifugal pumps under carbonate scaling conditions
  • Gradual dissolution of the paintwork causes the inhibitory M²⁺ ions to pass into the produced fluid
  • The reported effect is achieved with the M²⁺ concentration as low as 1 mg/l or less which is lower than conventional organic antiscalants by an order of magnitude. The fluid which contacts the ECP surface thus enters the pump inlet with sufficient concentration of the inhibitory ions
  • The coating thus functions as a protective layer which prevents carbonate deposition on ECP surface, and as an inhibitory ion carrier (dispenser) for feeding to operative parts of a pump

Coating Characteristics

  • Stable up to +300oC
  • No heat treatment or UV curing required for painted parts and products
  • An efficient combination of modifiers and surfactants ensures good flow properties of the coating material. Easy to use and to prepare for application
  • Can be applied without reskilling or special training of the personnel
  • Application requires no specific tooling or equipment
  • IMPORTANT: The surface must be thoroughly decontaminated, and totally freed of old paintwork
Composite Coating Preparation

Composite Coating Preparation

No special preparation of equipment is required to apply this coating. The coating shall be applied by maintainers at manufacturing sites without any extra safety requirements.

Our Achievements

A well with experimental ECP coating was shut down after 285 days in service. The shutdown was due to wellwork, i.e., the well ran normally right up to the shutdown. No scaling was discovered on the ESM body or on the operative parts of the ECP.

Preparation of composite coating

ECP after 608 days in service. The overhaul was due to wellwork, i.e., the well ran normally right up to the shutdown. No ECP scaling was discovered.

Preparation of composite coating

Conclusions

  • The coating can be prepared and applied at an ECP repair shop
  • After the pilot work was carried out, the TBO was observed to increase on the three ECP units
  • Throughout the pillow work time, the units ran without jamming, inlet pressure buildup, or motor temperature rise (according to telemetering)
  • It is promising to extend application to other frame sizes and ECP operating conditions