Maersk Oil – Optimising the use of diesel generators

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Problem statement

The Gryphon Alpha FPSO has five diesel generators and historically the operating philosophy has been to run two or three of these per day to power the thrusters. This is in addition to power provided by the two gas turbines. It was decided to explore ways to make this process more efficient.

Aim

Reduce the use of the diesel generators and seek out ways to power the thrusters more efficiently.

Method

Collaborated with the Barge Masters and Offshore Leadership team to explore the benefits of using the diesel generators less frequently.

A plan was put in place to power the thrusters using the gas turbines instead of using both the diesel generators and the gas turbines.

Impact

By using the gas turbines to solely provide power to the thrusters the FPSO has projected an annual cost saving of c.£1million:

  • Saving diesel fuel costs
  • Reducing service costs through extended service intervals based on lower running hours

Compared to 2016, 2017 has seen an average of 1.04 fewer diesel generators running since the implementation of the new operating philosophy.

On top of the cost savings, the practice has reduced noise and reduced the FPSO’s carbon footprint through fewer emissions.

Total savings anticipated: c£1m per year

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Maersk Oil – Using drones to optimise offshore inspections

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Problem Statement

The Gryphon Alpha FPSO has twelve cargo tanks and each one needs to be regularly inspected to stay on top of any maintenance needed. This is usually done by a four person rope access team and can take up to five days. The team investigated alternative ways of conducting this inspection to reduce risk to personnel, save time and reduce cost.

Aim

Use a drone to successfully and safely inspect one of Gryphon Alpha’s four storey tall cargo tanks with a view to incorporating drones into our regular inspection routine.

Method

The team worked with a specialist drone vendor to pilot the use of a drone to inspect an offshore cargo tank.

An expert pilot and inspector were the only people required to be in the tank with the drone during the inspection.

Images from the inspection were sent to onshore teams for further analysis within minutes.

If anything concerning was detected then arrangements would be made to contract a rope access team to further inspect and fix the anomaly.

Impact

It was the first time a drone had been used to inspect an offshore cargo tank.

The drone allowed us to inspect hard-to-reach areas without exposing personnel, reducing the overall risk to people throughout the activity while improving the quality of the data gathered.

The drone inspection was successfully carried out in just a few hours. Compared to a rope access team which could take days for the same sample – the saving is considerable.

The successful use of the aerial drone prompted the team to use a submersible drone to inspect a ballast tank, also on the Gryphon Alpha, again reducing unnecessary risk to people.

The team is also planning to use aerial drones to inspect the cargo tanks once again in 2017 with the support of a crawler to take thickness measurements – a device that can scale walls.

Using this method has the potential to save c.£5,000 per cargo tank without reducing the quality of the inspection.

Total Hours saved: Significantly reduced. A drone inspection takes around one fifth of the time

Total savings anticipated: Has the potential to save c.£5,000 per cargo tank.

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Maersk Oil – Improving gas compressor efficiency

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Problem Statement

The Gryphon Alpha FPSO’s gas compressors have had a history of piston rod failures; these failures can result in a six day outage. It was identified that the failures were due to liquid carryover into the gas compressors. The challenge was to find an efficient way to improve liquid removal without substantial impact to production. Context: Increased production volumes on Gryphon meant that the existing suction scrubber (liquid removal system) wasn’t effectively removing liquids from the gas prior to reaching the gas compressor. A new, much larger scrubber was installed and this improved performance but liquids kept appearing. This resulted in piston rod failures which led to unplanned shutdowns and production loss.

Aim

Consider methods to improve liquid removal, preventing unplanned failures of the gas compression system caused by liquids and the subsequent production loss.

Method

The Compression Enhancement project was kicked-off in 2014 which saw a number of improvement projects take place.

In 2016, the issue with liquids arose again so after considering options it was determined that installing a cyclonic separator would improve the existing design with minimum impact to production and without requiring significant physical modifications.

The cyclonic separator bypassed the original scrubber and the link between the two scrubbers was closed off.

Now, as gas enters the system from the first stage separator it is processed through the larger suction scrubber as normal before passing along a pipe to the new cyclonic separator unit and then it travels to the gas compressor

Impact

Cyclonic separators may be rarely used in the North Sea but the equipment has gone a long way, in a short space of time, to optimise one of the Gryphon Alpha’s gas compressors.

Result: there have been no first stage piston rod failures on this compressor since the unit was installed. Another cyclonic separator has now been installed on a second parallel Gryphon compressor.

Each piston rod failure results in a six day outage for the compressor. Based on four year’s worth of breakdown data and subsequent production loss, c.£1.5million can be saved per year.

Other benefits to using a cyclonic separator unit.

The unit creates a vortex to remove liquid particles from the gas so it has no moving parts resulting in no additional maintenance.

Liquid removal happens closer to the compressor and this greatly reduces the chance of liquid entering the compression system.

The cyclonic separator was installed utilising existing instrumentation requiring no significant physical modifications.

Failures of a high pressure gas compression system increases the risk of a potential process safety incident. By installing the cyclonic separator we’ve taken measures to reduce this risk.

Total hours saved: Installation of cyclonic separator prevents a six day production outage.

Total savings anticipated: c.£1.5million projected savings a year. Based on four year’s breakdown data and subsequent production loss.

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Maersk Oil – A new approach to well interventions: Cost effective and quick way to unplug subsea sand screens

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Problem Statement

The production from a subsea well went into severe decline and it was thought that the well’s sand screens needed to be urgently cleaned. The standard solution would have been to use a semi-submersible drilling rig with coiled tubing, but this is both expensive and slow. So, a new solution had to be explored and developed.

Aim

Find a cheaper and faster alternative to using a semi-submersible drilling rig to clean a subsea well’s sand screens and improve the well’s production.

Method

Formic acid was chosen to clean the screens.

To get the fluid down to the formation (a depth of 9,300 ft) it was decided to use a coil hose deployed from a light well intervention vessel (LWIV).

A LWIV is a smaller, more manoeuvrable mono-hulled ship. It’s often used for subsea well interventions but using wireline (electric cable) or slick line (thin wire).

Coil hose is very different from coiled tubing in that it can be rigged up using slick line equipment, still allowing pumping to take place.

10,000ft of coil hose with an outside diameter of 19mm needed to be deployed – the size of the hose meant that the pump rate would be low.

To tackle this, several new pieces of hardware had to be designed, manufactured and tested. Numerous programmes and safety reviews were also carried out.

Impact

The intervention was completed incident free and initially the well production rate doubled.

This successful result confirmed our hypothesis that the decline was due to screen plugging. This is useful learning for the future.

The intervention saw three world firsts:

  • The first time coil hose had been run from a light well intervention vessel;
  • The first time coil hose had been run into a subsea well; and
  • previously nobody had run coil hose deeper than 2,000 feet – we ran it to 9,300 feet.

Overall timing from concept creation to execution was just four months – a significant reduction compared to the alternative method of using a semi-submersible rig.

The success of this job has allowed us to look at other candidates for cost-effective well intervention to improve production.

Reduced project timeline: Total project timeline was 4 months, compared to 6-8 months needed for semi-sub intervention (inc. contract)

Total savings anticipated: Around 30% saving – compared to the alternative solution of using a semi-sub rig and coiled

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Nexen – Significant savings made by changing to alternative valve in well interventions

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Problem statement

Nexen routinely used Shear Seal Valves in well interventions but the dimensions of the valve actuator caused logistical problems which cost time and manpower.

Aims

To reduce cost and manpower in well interventions.

Method

  • An alternative valve design was sought which would reduce cost and logistical problems.
  • The Slimbore Shear Seal Valve was identified which uses a ball valve to create a valve which has tall and slim dimensions.

Impact

  • Nexen has saved approx. £30,000 per each well intervention as a result of changing to an alternative valve.
  • Nexen is now using Slimbore Shear Seal Valve, which uses a different type of valve (ball valve) to create a valve which has tall and slim dimensions.
  • The valve fits through a much smaller aperture and means that a much smaller deck plate can be removed manually.
  • The valve can also be lifted and placed using the in-situ wireline mast tugger line which removes the requirement for a platform deck crew, crane driver and scaffolders.

Total well interventions 20  (2015 & 2016)

Total savings anticipated £30,00o per well intervention

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Global Energy Group: Integrated Caisson Team – a Collaboration of Expertise

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Problem Statement

Caissons are used in a variety of applications on offshore production platforms and vessels. Common uses for caissons are firewater and seawater lift, drain, as well as I/J-Tube applications. Due to platform life extension, caissons have often been in place longer than planned, and deterioration and failure of caissons is a growing trend in the North Sea and worldwide. This deterioration and failure may present a dropped object risk to subsea structural and piping systems. Their size and location also often make them difficult to access.

Aims

As there are a number of caisson-related issues across late-life assets, Global Energy Group (GEG) has reacted to the industry-wide issue of caissons with a bespoke offering via our Integrated Caisson Team (ICT). This initiative provides a cost efficient and value-added turnkey caisson solution and one-stop shop service.

Method

In an industry where innovation and collaboration are key, the ICT is a seamless approach and also offers the opportunity to have one interface and a unique commercial offering.

This ICT is made up of a number of companies with specialities dealing with caisson issues. We’ve teamed together to provide a collaborative offering, cost-efficient and value-added turnkey solution for
caisson-related scopes.

Impact

The philosophy behind the ICT model is the provision of a one-stop caisson remediation and replacement offering that identifies best value solutions by combining the services of selected ICT partners throughout the project life cycle.

Of significant value is the ability of the ICT to offer options to a variety of solutions from within the structure of the ICT, without the need to bring in additional external resources. Examples include:

  • Options for either welded or weldless connections of caisson sections
  • The use of conventional rigging equipment or specialist caisson lifting tools during destruct and construct
  • Options to coat caissons with client-specified coating systems or utilisation of
    one-coat systems complete with coating warranties during the fabrication process
  • Options to install marine growth prevention systems at the time of caisson installation, or as retrofit solutions to existing caissons (this option is available to risers, conductors and structural tubulars)
  • Options for nitrox diving capability to 50 metres or cofferdam support in the
    splash zone
  • Alternative access solutions including rope access, WEB deck and tension netting systems, all installed by multi-disciplined access and trade technicians
  • Options for platform, vessel or daughter craft-based diving operations

The ICT is also a platform for knowledge sharing across varied specialist skills and tooling:

  • GEG – inspection, survey, design, fabrication, repair, construction/installation – both topside and subsea
  • Acotec – Solvent free one-coat Humidur coatings and underwater cofferdams
  • STATS Group – caisson securing and lifting tools
  • GMC – weldless connectors
  • CETCO – temporary produced water systems
  • Cathelco – cathodic protection systems

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Lokring – Retaining Non-Hazardous Areas without Welding

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Submitted by Tom Brown, Technical Sales Manager.

Problem statement

  • A Northern North Sea asset had to replace a 2’’ stainless steel fuel gas system which ran through both hazardous and non-hazardous areas.
  • The system therefore had to be ‘fully welded’.
  • The only way they could do this under traditional methods was to weld the pipe on the platform.
  • This was not possible due to the spacing restrictions in this instance.

Aims

  • To replace the system as a fully welded one so the non-hazardous areas could remain this way, without actually welding on site.

Method

  • The operator had used Lokring before on fuel gas, but was not sure if it could be used on a fully welded system in a non-hazardous area without reclassifying the area as hazardous, as would have to be done when installing a flange.
  • To get confirmation, the operator contracted Xodus to carry out a study on whether a Lokring coupling could be used in this situation while maintaining the non-hazardous area classification.

Impact

  • The findings of the report confirm that;
  • ‘There is strong, well-supported justification for the use of LOKRING fittings in place of welded connections on the fuel gas system located in a non-hazardous area. The work completed for this study is judged to have suitably justified weld-equivalence for LOKRING fittings in non-hazardous areas, which by inference facilitates the support of their use in hazardous areas also.’

How does this relate to the Oil and Gas industry?

  • Traditionally, when installing fully welded pipework, the only option in non hazardous areas of a platform have been to weld on site.
  • This takes time, involves hot work permits, welders, habitats, fire watch and there is always the safety risk welding on site
  • This study has now provided another option to welding fully welded systems, while at the same time being quicker, safer and more cost effective.

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SETS – Applying the Subsea Standardisation Principles to Subsea Structural Repairs

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Submitted by Kevin Milne, Business Development & Brand Manager. 

Problem Statement

Utilisation of dive support vessels (DSVs) to fix and repair subsea structures on fixed assets is time sensitive, expensive and often inaccurate. Application of the principles of subsea standardisation/fit for purpose offers the potential to test interventions which do not involve DSVs.

Aims

  • Apply the principles of subsea standardisation to brace repairs and identify a fit-for-purpose approach.
  • De-risk an alternative intervention both commercially and technically in order to deliver the most efficient solution to meet the client’s requirement.
  • Reduce operational expenditure (OpEx) by challenging typical approach and methods.

Method

  • The SETS team worked with the project team early on to review the project scope and applied the standardisation principles to identify opportunities for improvement. The scope was then revisited and re-worked with a more realistic consideration of risk.
  • A focus on commercial risk was introduced.

Impact

Early involvement and application of a standardised/’fit-for-purpose’ approach resulted in:

  • Elimination of non-productive time
  • Consideration of all technical and commercial contingencies before the DSV left the harbour wall
  • Reduction of DSV requirement by 11 days
  • Work-scope successfully delivered with considerable cost and time savings.

Total hours saved: 264

Total savings anticipated: £1m +

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Maersk Oil – Engineering a unique solution

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Problem statement

Correcting the slippage of buoyancy modules on the Global Producer III FPSO vessel’s risers without replacing the riser or carrying out a planned shutdown is an extremely expensive and risky operation.  The challenge was to find a way to correct this slippage whilst keeping the riser in operation, something that hadn’t been done before.

Aim

To correct the buoyancy module slippage in a targeted manner using a remotely operated vehicle (ROV), allowing us to move away from conducting saturation diving operations and also engineer a solution that could be implemented whilst in operation.

Method

  • The Maersk Oil team engaged with SubC Partner, inventor and owner of the technical solution. Over six months, the team created a bespoke tool that connected to an ROV.
  • The tool had to be specifically designed for the task because there were a number of specific requirements.
  • It had to work underwater while connected to the ROV, dock onto the riser and remove the old buoyancy module and inner clamp. It had then to bring the old parts to the surface, pick up the new clamp and module and go back down to the riser to install the new parts.
  • The new clamp was also installed with rubber compliant pads to stop future slippage, a technique already effectively used by Maersk Oil.

Impact

  • Replacing the buoyancy modules on a live riser system had never successfully been completed before. The Maersk Oil team met this challenge head on and in collaboration with SubC Partner, a bespoke tool was developed to replace the buoyancy modules, correcting the slippage.
  • The solution avoided the need to replace the whole riser, an extremely expensive and risky operation, and also meant that the riser could be kept in operation during the replacement, resulting in no production loss.
  • By using a tool docked onto an ROV the need for saturation diving personnel was eradicated, reducing the risk to human life.
  • The installation of rubber compliant pads on the inner clamp helps prevent future slippage.
  • Replacing the buoyancy modules is more efficient compared to the alternative of replacing the riser entirely; there was no impact to production and the solution saw around 80% savings compared to alternative method. This solution has been shared at a Society for Underwater Technology (SUT) lecture.

Total hours saved: No significant saving

Total savings anticipated: Solution cost approx. 20% of the average fee of replacing a riser, around 80% saving.

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Agilis – Cost estimate certainty

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Problem statement

From 2011-2016 fewer than 25% of oil and gas projects in the UKCS were delivered on time. Projects averaged 10 months delay and came in around 35% over budget (OGA).

Aims

Use better techniques to improve oil and gas project cost estimates.

Method

Collaboration between Agilis, a process improvement consultant and Barnett Waddingham, a leading UK actuarial firm.

Agilis cost model framing workshop engages with uncertainty and addresses bias. Barnet Waddingham draw on their experience of probabilistic modelling and estimate governance for the insurance and financial sectors to provide a more rigorous cost model for oil and gas projects that recognises complexity and reduces uncertainty.

Impact

  • Better understanding of project risk exposure: avoids over/under-provisioning
  • Allows planning for uncertainty: e.g. pre-emptive “delay analysis”
  • Provides a robust and transparent governance standard familiar to banks, investors and government: cheaper finance

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