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TRANSCRIPT
NSRI: Support for the Developer Community
Ambient Lifting and Ballast Technology Update
23rd September 2015, Michael Cowie
Presentation Overview
• Ecosse Subsea Systems
• ESS Ethos
• Imagine if……
• Ambient Lifting Technology – theory and examples
• Status of technology
Ecosse Subsea Systems
ESS is a Technology Based Company:
• Established in 1996
• 100% Scottish owned
• Initially O & G focused, diversified into Offshore Renewables
• Core business:
Ø Subsea engineering consultancy
Ø Offshore contracting
Ø Technology development and implementation
ESS Ethos
Provision of Subsea Services that are focused on being:
• Safe
• Simple
• Robust
• Cost-effective
Ø Off-the Shelf Components
Ø Negate the requirement for specialist vessels
Ø Installable by local people and vessels
Ø Recoverable, recyclable
Imagine if……..
• Image installing a 450Te Foundation utilising a Multicat Vessel in extreme environmental conditions……
• Imagine recovering a 600Te+ structure using an Anchor Handler vessel in remote locations……
This can be achieved with Ambient Lifting and Ballast Technology where:
Ø Spread cost is more than halved
Ø Weather risk is significantly reduced
Ø Vessel choice is increased
Ambient Lifting
Ambient Lifting – General Overview
• Ambient lifting is a flexible mechanism that allows you to control the ascent, descent and underwater positioning of offshore structures.
• Innovative subsea lifting without use of heavy-lift vessels.
• Ambient lifting can be used in a variety of industries including Oil & Gas, Decommissioning, Offshore Wind, Wave & Tidal Energy.
Ambient Lifting:
Theory Examples
9
Te
300Te
Neutrally Buoyant
• Structure is designed to be buoyant when flooded with fluid
• Structure is positioned over structure to be recovered
Structure INSTALLATION / RECOVERY Example
10
Te
• Structure is neutrally buoyant• Structure encloses over top of structure and
is locked in
300Te
Structure INSTALLATION / RECOVERY Example
11
Te
• Fluid in receptacle is replaced by gas• Structure is recovered to surface in a very
controlled manner
Structure INSTALLATION / RECOVERY Example
300Te
12
Te
250Te
0kg
• In air structural weight
Structure FOUNDATION Example
Te
13
250Te
Neutrally Buoyant
250Te
250Te
• In-water structural weight• Buoyancy in receptacle designed
to ensure structure is neutrally buoyant
Structure FOUNDATION Example
14
Te
250Te
250Te
0-200Te
250Te
• In-water weight increased by adding ballast material
• Structure sinks to floor in a very controlled manner
Structure FOUNDATION Example
15
Te
250Te
250Te
250Te
200Te
• Gas is replaced or compressed by fluid• Now in-water structural weight plus
weight generated by water in receptacle• Design ensures sufficient for temporary
stability
Structure FOUNDATION Example
16
Te
250Te
250kg
250Te
3 x Wt=600Te
• Fluid is be replaced by denser fluid• Fluid has SG = 3 and is pump-able• On-bottom weight is trebled• Structure is fit for extreme environmental
loading
Structure FOUNDATION Example
17
Te
• Reverse process for recovery• Fluid replaces heavy fluid
Structure FOUNDATION Example
18
Te
• Structure is neutrally buoyant• Structure is returned to surface in a
very controlled manner
Structure FOUNDATION Example
Te
19
250Te
Neutrally Buoyant
• Structure on surface• Can be towed to quayside for recovery
Structure FOUNDATION Example
Foundation Installation/Recovery Example
Steel Frame (Lower Sec/on)
Lower pipework sec/on (approx. 5000m)
First pipe sec/on loaded to Steel Frame on quayside and secured
Lower sec/on steelwork and pipework loaded in to water
Mass Buoyancy Net Upli2
Second pipework sec/on loaded into Steel Frame in Quayside water
Mass Buoyancy
Net Upli2
Third pipework sec/on loaded into Steel Frame in Quayside water
Mass Buoyancy
Net Upli2
Upper steelwork aBached to Steel Frame in Quayside water
Mass Buoyancy Net Upli2
BoBom third of ABL pipework filled with SG 2.5 fluid prior to tow out.
Mass Buoyancy
Net Upli2
50Te external ballast added to frame prior to tow out.
Mass Buoyancy
Net Upli2
Second vessel arrives in the field to assist in ballas/ng opera/ons.
ABL unit is aBached to both vessel winches. The unit is ballasted via the control umbilical un/l it has a nega/ve buoyancy and both winches are showing a weight of 5-‐10Te.
Vessels simultaneously pay out on winches to lower the founda/on to the seabed.
Upon laydown on the seabed, the ABL unit can be fully water ballasted and then disconnected.
On boBom weight when fully water ballasted with boBom third filled with SG 2.5 fluid External Ballast=131Te
For recovery of unit the removal of heavy fluid from top two HDPE sec/ons gives a net upliX of 17Te for tow back to port. Reverse Process to installa/on.
Subsea Structure Recovery Example
Two AHTS vessels are implemented for the removal of the subsea Structure
19m
4m
LiX connec/on points to be located in Structure 600Te
The ABL unit is constrained by tow chains from the vessels.
The ABL unit ballasted down to connect to the Structure.
ABL aBached to the Jacket Foo/ng using the mechanical connectors shown on following slide.
Male por/on aBached to underside of ABL frame
Female por/on to be placed on the founda/on.
Upon connec/on, buoyancy is added to ABL unit to liX Structure from the seabed.
The unit can be towed by a single vessel to port for decommissioning.
Ambient Lifting – Status
Work to date: • Technology is patent pending, submitted July 2014 • Prototype constructed, 1:10 model
• Test tank procured for ESS Workshop • Successful prototype trials undertaken • Trials witnessed by potential Clients • Secured 1st Project – installation of gravity based foundation
• 450Te foundation being installed with multicats in extreme currents, Q1/Q2 2016
• In discussions with a number potential Clients for Ambient Lifting as lifting systems and as removable foundations.
• In discussions with Diving TA’s for Ambient Lifting as alternative to air-bags
Going forward: • Renewables and Decommissioning focus • Looking for demonstration opportunities and funding support
