Successful LGS® field deployment validates product’s capability in offshore operations

Matrix Composites & Engineering Ltd (ASX:MCE, “Matrix” or the “Company”) is pleased to announce that it has successfully completed a 12-month field deployment of its Longitudinal Grooved Suppression (LGS®[1]) system in the Gulf of Mexico with a leading oil and gas operator.

LGS® is an Australian-developed and patent-protected technology that reduces drag and vortex induced vibration (VIV) on tubular structures exposed to strong ocean currents, enabling drill rigs and platforms to continue operations through strong ocean current conditions, and, in turn, driving up production and efficiency and reducing downtime and equipment fatigue.

The field trial results have demonstrated that Matrix LGS® works as predicted in full-scale, real world operations, following similar, large scale tank testing that first demonstrated proof of concept.

The LGS® system was deployed in an area where the operator experiences strong currents, which had resulted in drilling downtime. Analysis of the field results has shown that the LGS® system allowed for safe, uninterrupted drilling to continue during ocean current conditions where standard buoyancy would have proved inoperable.

Annual operability improvement of using the deployed LGS® string section is calculated to be 12 days, resulting in annual savings of $US12.7 million [based on current average daily drilling rates]. As such, it is calculated that it would take 1.35 days of recovered operability to pay back the purchase cost of the LGS®.

With these latest findings, Matrix is ready to expand its LGS® application into other areas in the subsea drilling sector, with the product applicable to any marine structure exposed to strong ocean currents.

Aaron Begley, Matrix Chief Executive Officer, commented:

“The results from the field deployment in the Gulf of Mexico validate that Matrix LGS® works as expected in full-scale real-world operations. The application of LGS®reduces total drag and VIV, improving operations and reducing costs achieved from increased drilling time.

“Offshore operators in high current conditions, such as in the Gulf of Mexico, are required to suspend drilling operations due to high currents, which adds substantial cost to operations. The Matrix LGS® system allows operations to continue safely and effectively. The cost savings are substantial, and we are excited to have the results behind us to validate the application of LGS® to a multitude of marine operations.”

LGS® Development

The success of LGS® has been a great feat for Matrix, which mooted the concept back in 2014 to combat current induced drag and VIV in offshore drilling. The drag caused by ocean currents can deflect drilling risers to the point where operations are halted. Vibrations caused by eddies forming from currents flowing around a pipe can fatigue structures, thereby reducing their service life.

One of the issues Matrix had to address was how to design something that would consider the lightweight buoyant cladding that wraps around cylindrical marine risers.  Prior to the development of LGS®, the only way to reduce drag and VIV in marine drilling risers was to fit large wing-type structures called fairings to the outside of the cladding. Fairings are time consuming to install and regularly break away from the cladding. Helical patterned fins called ‘helical strakes’ were also trialled but were found to increase drag. Therefore, Matrix focused its efforts into developing a product that could be molded to the buoyancy, and simultaneously reduce both drag and VIV.

Matrix partnered with engineering consultants, AMOG, which had expertise in offshore structures, risers and moorings.  AMOG used the features of the giant Saguaro Cactus and adapted them for use in water to create what would become the LGS® product.  This particular cactus has a small root system but can survive high winds, with a grooved profile on its outer skin that wind tunnel tests showed provided protection against drag and VIV.

The LGS® profile is therefore known as ‘BioMimetic’, in that it mimics a naturally-inspired process.  Other Biomimetic technologies can be found here.

Gulf of Mexico field test

Matrix and AMOG, in conjunction with a large oil and gas company, conducted field trials with 609 metres (2,000 feet) of LGS® at a depth of 1,980 metres (6,300 feet) in the Gulf of Mexico from July 2017. The purpose of the trail was to validate, in an operational environment, the VIV and drag reduction characteristics derived from the high Reynolds number testing conducted at the National Research Centre in St John’s, Canada.

The riser used in the Gulf of Mexico was fitted with motion sensors. The sensors captured movement and vibration in the riser when deployed underwater. Matrix then compared the data from the Matrix LGS® string with similar current profile data using a conventional, cylindrical buoyancy string. This allowed Matrix to further demonstrate the efficacy of the system in strong current conditions experienced offshore.

The field results and analysis taken from a strong current period in January 2018 show that without LGS®, and with the same rig offset, the upper flex joint (UJF) angles would exceed 2 degrees for this period. This demonstrates that LGS® has already improved Mobile Offshore Drilling Unit (MODU) operability in the field by improving the UFJ angle.

This analysis demonstrates that had the LGS® buoyancy not been installed, UFJ angle of 2 degrees would have been exceeded in January, rendering the rig inoperable during that period.

The LGS® model has been validated against MODU field data. It shows that the annual operability improvement using the LGS® buoyancy is calculated to be 12 days. Average annual savings (originating from increased operability) are calculated to be $US12.7 million. With the deployed LGS® string section costing $1.4 million, it would take 1.35 days of recovered operability to pay back the purchase cost.

Financial evaluation basis:

  • Daily rig hire rate of $564,000 assumed, plus additional $500,000 in other daily spread costs
  • 2 degrees UFJ angle used as operability limit, with no rig offset.

There were three eddy current profiles at various peak current speeds during the field test. 50 total cases, with associated annual probabilities of occurrence and the peak current speeds from 0.3-2.3 m/s. The changes in persistence of eddy currents impact operability improvements and therefore costs.

The risers used in the Gulf of Mexico were fitted with motion sensors. The sensors captured movement and vibration in the riser when deployed underwater.

The additional benefits of LGS® full string coverage versus LGS® partial string coverage was also substantial. Entire string of LGS® modules are predicted to provide an additional 2 days per year of operational latched time. This results in an additional saving of $2 million per year with base cost assumptions. Additional cost benefits from a full LGS® riser string compared to a partial LGS® riser string include deployment, retrieval and crabbing performance.

Large scale testing

Following AMOG’s small scale testing at Monash university to optimise the profile of LGS®, and prior to field testing, Matrix and AMOG engaged Oceanic Consulting Corporation to conduct large scale tests of the LGS® at Canada’s National Resource Council in St. John’s, Newfoundland, Canada.

The test facility, the largest of its kind in the world, is renowned for conducting several high-profile oil industry JIP (Joint Industry Project) test programs for VIV and drag reduction assessment. The size of the St. John’s facility enabled large scale models of the LGS® profile to be tested under high load and high current speed conditions. The outcome of these tests exceeded predicted results from the small scale tests, with testing demonstrating that the unique profile of LGS®reduces total drag and VIV, substantially surpassing the performance of current state of the art technologies. These attributes open up applications for LGS® in a broad variety of offshore applications including both drilling and production riser applications.

Large scale prototypes were fabricated at the National Research Council Canada (NRCC) facility in St. John’s for both profiles around test cylinders approximately 5.88m long x 385mm diameter. The prototypes were assembled onto a large test rig and dragged through a water filled test tank and the amplitude and vibration of the profiles measured for a range of speeds. These were performed under three different scenarios:

  1. Fixed mode, where the profiled test cylinder was fixed under the test rig
  2. Free vibration mode, where the pipe was free to move laterally
  3. ‘Plucked’, like a guitar string, and the translational response measured.

These tests were benchmarked against a bare cylinder of the same dimensions. Over 75 tests were performed at differing accelerations, decelerations and sped up to 3.5 m/s over 10 days.

The tests demonstrated that Matrix’s LGS® reduced both VIV amplitude and the resulting drag coefficient.  Importantly, the larger scale also allowed the tests to work at higher Reynolds numbers (up to 1.6 × 106). (Reynolds numbers are a dimensionless number used in fluid mechanics to indicate whether fluid flow past a body or in a duct is steady or turbulent.)

This was an exciting result for Matrix as it was well into the post-critical flow regime that would be experienced offshore.

The various tests concluded:

  • Fixed mode tests showed lower drag than fairings:
    • The fixed drag coefficient over a range of towing speeds (and, therefore, Reynolds numbers) averaged below 0.6.
    • This level of drag is lower than that achieved by fairing equipped risers and significantly lower than that achieved by a bare cylinder.
    • The Amplitude of Vibration Divided by the Diameter of the VIV response is a measure of the vibration severity also called A/D.
  • Free vibration mode tests: VIV amplitude less than 0.25 A/D VIV during the tests was minimal. So small, in fact, that the test assembly was often ‘plucked’ to initiate VIV and provide a conservative estimate of VIV behaviour.
    • The typical VIV amplitude was less than 0.25 diameters, a significant reduction from the earlier sub-critical testing.
    • This reduction in VIV amplitude further reduced the amplification of the drag coefficient.
    • The maximum total measured Cd was 0.8 including VIV amplification. Overall, the high Reynolds number tests confirmed the clear advantage offered by Matrix-LGS® technology for use on drilling risers in high currents, with resultant low drag and minimal VIV excitation.

Further applications

Matrix LGS® has a broader application outside of marine risers, being applicable wherever there is a requirement for VIV and drag reduction around cylindrical structures. Applications include subsea pipelines, jetty pylons, piled structures such as offshore wind turbines, production risers, and cables.

Other growth and expansion plans include a new round of research into applications for scour protection and the removal of foundation soil from around tubular structures like pylons, due to commence in 2018.

For further information please contact:

Peter Pezet
Strategic Business Unit Manager
Oil & Gas Products  
Ph: +61 8 9412 1200
Email: peter.pezet@matrixengineered.com 

Tricia Hill
Business Development Manager
Americas
Ph: +1 832 277 3831
Email: tricia.hill@matrixengineered.com

To download a PDF version of this release please click here.

About Matrix Composites & Engineering

Matrix Composites & Engineering specialises in the design, engineering and manufacture of composite and advanced material technology solutions for the oil and gas, civil and infrastructure, resources, defence, and transportation industries. With more than 40 years-experience, Matrix has gained a reputation as an industry leader and has become a major exporter of Australian goods and services with customers located all over the world. From its award-winning head office in Australia and offices in the United states, and a global network, Matrix is uniquely positioned to deliver complete turnkey solutions offerings with localised customer support.

More information can be found at www.matrixengineered.com.

About AMOG

AMOG Technologies Pty Ltd is part of the AMOG Group of Companies, wholly owned by AMOG Holdings Pty Ltd. Established in 1991, AMOG is a high-end engineering consulting firm providing global engineering solutions to the energy, resources, rail, defence and maritime construction industries.

For more information visit our website at www.amog.consulting.

[1] LGS is a registered trademark of AMOG Technologies Pty Ltd. Matrix has the exclusive world-wide licence to commercialise LGS.