V-LIFE: A means of rejuvenating failing umbilicals and subsea electrical distribution systems

MCE Deepwater Development March 2015

Electrical Failures

Electrical Failures in connectors and cables can result in one of three failure modes:

Short Circuit

Open Circuit

Line Insulation Failure – current leakage to earth

Fault types can be classified as either:

Intrinsic – the fault relates to design, materials or hardware assembly

Extrinsic – the fault relates to handling, installation, environment, mechanical stressing and/or misapplication

Intrinsic Failures

Elastomeric failures (including bellows)

Polyethylene moulding failures (cathodic disbondment)

Nascent Hydrogen in Umbilicals and gassing

Poor soldering (flux, excessive quantity, sharp edges)

Use of incorrect crimping tools

Cracks in epoxy in connectors

Shuttle pin assembly failure

Extrinsic Failures

Calcareous and/or marine deposit around compensation and pin shrouds

Lateral mechanical stresses placed on connectors when cables are installed on structures

ROV impact damage

Connectors left exposed subsea for too long(not properly parked or protected)

Cable sheath damage

Fishing/trawl board impact

Water trees/Electric trees

Water permeation into insulation

Moisture Intrusion can occur in long-term wetted cables in the majority of commonly used insulation materials. The intrusion results in:

Decrease in dielectric strength

Increase in leakage currents

Continual degradation leading to eventual failure

The cost of subsea electrical failures is significant –

Marine intervention costs

Replacement hardware

Lost production

Water ingress into electrical cables

A scientific breakthrough to reverse low insulation resistance

The Solution – V-LIFE

The Process – Utilises electro-kinetic & electro-chemical phenomena to increase the resistance of the conductive path between the copper conductors and ground.

The Result – Increased Insulation Resistance, extending thelife of the failing cable / connectors, increasing system availability and reducing the need for subsea interventions and equipment replacement.

V-LIFE hardware – in portable form

Example of restorative effecton a Subsea Cable using V-LIFE

Example of restorative effectlong-term V-LIFE trial

V-LIFE down-powered for 7 days

Measure

AnalyseImprove

Active control

Through continuous monitoring, the V-LIFE system is adjusted to maintain the desired effect.

V-LIFE benefits

Reverses the effects of water ingress into electrical cables and equipment

Can extend the life of failing umbilicals:

‘Buys time’ whilst a new umbilical is procured

Used instead of installing a new umbilical

Can be used to postpone field abandonment

Can increase technical margins to allow additional wells to be added

Can rejuvenate other subsea distribution equipment and components

V-LIFE results to date

Eight systems installed and operational

100% success rate

IR can be increased from as low as 23kΩ

IR reaches a plateau after 3-4 months. Minimum achieved is 60MΩ, maximum is >100MΩ

Major economic benefits already proven for operators:

Two have postponed new umbilical installations indefinitely

Used to re-establish production in one field