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Atex-Compliant Variable speed drive:
A considerable advantage for our mature fields

A project presented by Jean-Grégoire Boero Rollo, Jérôme Long, Brice Bibanzilha, Vincent Marec andJean-Jacques Bassafoula

Jérôme Long

Drilling & Wells

Our new mobile control module — a variable speed drive that can be used in an explosive atmosphere (VSD ATEX) — fills an important gap by making it possible to convert oil platform installations at a lower cost to use an electric submersible pump (ESP) system instead of gas lift for production. Our innovation plays a decisive role in profitably maximizing the output of mature offshore fields and opens up new prospects in this area. We are also integrating this technology brick in our lean platform concept, which will expand its use to greenfield developments.

A New Generation of Electric Pumping Systems

Until now, there were three roadblocks to switching mature fields to ESP systems: short pump life, the cost of conversion and the cost of modifying the topsides of offshore platforms to add or enlarge an electrical room. Since 2014, our Total E&P Congo (TEPC) affiliate has been working on optimizing the average lifespan of electric pumps, which has risen from two to four years, and on reducing conversion costs by shortening the works phase.

However, platform extension costs remained very high. To eliminate the need for costly modifications, in 2017 TEPC's teams started testing a new smart mobile control module called, an ATEX-compliant variable speed drive (ATEX). Because this VSD is designed to be installed outside the electrical room and used in an explosive atmosphere (ATEX), there is no need to adapt the topside installations. This means several million euros in savings for ESP conversion projects.

Our Technology's Strengths

The VSD ATEX is based on a new generation of variable speed drives developed by Leroy-Somer, known as Powerdrive MD3, an induction motor drive that uses insulated gate bipolar transistor (IGBT) technology. The solution's main strength is the improved cooling system with pass-through assembly and a dedicated air duct for the power module fans. The speed drive's human-machine interface is also compatible with equipment based on different technologies. What's more, the module's very small footprint makes it easy to install on any offshore platform.

Our electrical engineers significantly modified the commercial version to meet the requirements of equipment operating in an environment with an explosive atmosphere and designed a compact ATEX-certified enclosure. The team also integrated the electric pump flow controller in the enclosure to reduce the number of exterior connections. After the French National Institute for Industrial Environment and Risks (INERIS) certified the solution as ATEX compliant in April 2018, VSD ATEX was tested at Total's supply base in Pointe-Noire, Republic of the Congo.

Gradual Deployment in Republic of the Congo

A pilot was launched in the summer of 2018 on the mature Yanga field’s YAF2 platform in the Pointe-Noire Grand Fond (PNGF) license. The solution quickly improved production and operational efficiency:

  • The YAM254 well's output increased by 250% and reserves doubled after the switch to an ESP system in September 2018. Overall operational efficiency rose by 25%.
  • In all, the Yanga field's production grew by 10%.
  • The total cost of modifying the platform came to €400,000, which was 20% below budget and compares to €10 million for the installation of an ESP system with a conventional VSD on a platform at the nearby Sendji offshore field. The pilot paid for itself in six months.

In light of this successful performance, a broader development plan was launched at Sendji, where the use of gas lift is expected to decline from 63% today to 21% by 2021. Successive conversion projects will enable to reduce high-pressure gas requirements and shut down two gas compressors. Starting in 2021, it will be possible to couple the ATEX-compliant VSD with wireline retrievable ESP technology (WRESP), making well conversion easier. This technology could soon be extended to all of the affiliate's sites, as well as elsewhere at TotalEnergies.

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