RiSE issue 5

Balmoral DuraFloat LDV glides through tests

Balmoral DuraFloat LDV buoyancy is a result of Balmoral’s constant innovation drive to provide clients with industry-leading technology to help reduce offshore operational costs.

DuraFloat LDV (patent pending) technology integrates vortex induced vibration (VIV) suppression and drag reduction into drill riser buoyancy modules to increase rig efficiency without compromising on safety or structural integrity. The system minimises vessel down time, directly relating to significant cost savings.

DuraFloat LDV is designed to provide optimum uplift values while offering up to 75% VIV suppression efficiencies which dramatically improve riser motion and drag in onerous subsea current environments compared to traditional drill riser buoyancy.

The revolutionary hex design eliminates the need for ancillary suppression equipment and helps reduce time-consuming activities when running and removing drill stacks.

Additionally, it is recognised that reduced riser motion due to VIV suppression dramatically improves the fatigue performance of subsea equipment resulting in further cost savings by extending the service life of wellhead and conductor/casing equipment.

“DuraFloat LDV’s revolutionary profile was inspired by the carapace pattern of a sea turtle, the shape of which has been sculpted over millennia to provide an extremely efficient and low drag hydrodynamic structure”, says Dr Aneel Gill, product R&D manager at the company.

“We industrialised this natural phenomenon by the use of biomimetic engineering resulting in a man-made structure capable of offering VIV suppression and low drag performance. Extensive CFD and fluent modelling of the design was carried out, indicating up to 75% efficiency in VIV suppression and diminished drag by up to 33%.”

Half scale tank testing was carried out at SINTEF Ocean that confirmed strong operating performance. Testing of the modules was the largest project the renowned test centre had ever undertaken, the parameters are detailed below:

  • Test sample OD 0.611m. with an L/D ratio of 13
  • Reynolds number (6×105 – 3×106) with varying surface roughness ratios (1×10–6 – 1×10–4)

Tests included:

  • Fixed cylinder tests
  • Free oscillation tests
  • Forced motion test
  • Flow visualisation trials

Suitable for use on

  • Marine drilling risers
  • Jumpers
  • Long pipeline spans
  • Production risers
  • Umbilicals
  • Flowlines
  • Geometry can be utilised for traditional VIV strakes

Benefits

  • Significantly reduces VIV and drag when compared to conventional buoyancy
  • Improved operational envelope
  • Reduced drag and loads during deployment/recovery, riser disconnect and hang off
  • Significant reduction in VIV fatigue damage
  • Negligible loss of buoyancy
  • Eliminates assembly/recovery times
  • Easily stacked vertically and horizontally
  • Can be used with existing riser handling and storage equipment

DuraFloat LDV

  • Drilling riser buoyancy foam
  • Modules are produced using proven manufacturing techniques
  • Minimal buoyancy loss
  • Operational to 4500msw
Durafloat LDV
Durafloat LDV

DuraGuard LDV

  • Retrofit option for existing drill riser buoyancy modules
  • Significant cost savings via re-use of existing buoyancy
  • Alternative to VIV strakes
  • Improved handling and stacking
  • Improved roller deployment

Integral clamp LDV buoyancy

  • Alternative to VIV straked production riser buoyancy
  • Utilises patented integral installation methods
Durafloat LDV
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