Tailored Solutions for Subsea Flowline Integrity Surveillance Programs

Baseline inspection project to assess internal corrosion and geometrical anomalies

In a Nutshell:

Operators are forced to face a variety of complex challenges within pipeline networks, especially those relating to in-line inspection. Typical challenges include mechanical design, operating conditions and the properties of the product being transported. In this case, an operator was looking for an inspection provider to participate in their baseline inspection project to assess internal corrosion and geometrical anomalies for the 2 production loops at the Floating Production Storage and Offloading facility (FPSO) "Liza Destiny" in Guyana's ultra-deepwater region (above 5,000 ft).

For the operator, it is important to develop an inspection baseline and identify any internal corrosion at an early stage to adapt the operational strategy and improve the mechanical integrity program. This case presents several major challenges for inspection: high pipeline pressure in a deepwater application, challenging pipeline design for pigging (e.g. multi-diameter, 3D bends, piggable wye), solid deposits (e.g. asphaltenes) and heavy pipe wall.

RoCorr IEC (internal eddy current) technology is capable of accurately detecting and sizing shallow internal corrosion. This high-resolution eddy current inspection technology is suitable for application in heavy-wall pipelines when external damage is not of primary concern.

In this success case, ExxonMobil deployed an integrity management campaign of the Liza Phase 1 Project utilizing the RoCorr IEC technology and the tailormade solutions provided by ROSEN to inspect a total of 45 km of pipeline.

Project background

ExxonMobil initiated their oil and gas exploration activities in Guyana in 2008, collecting and evaluating substantial 3D seismic data that led to the company safely drilling its first exploration well in 2015, "Liza-1."[1]

Liza Phase 1 Project Description:

  • The Liza Phase 1 development covers approximately 190 km of offshore assets in depths of 1,500 to 1,900 m.
  • The project includes a floating production, storage and offloading (FPSO) vessel – “Liza Destiny” – that currently produces more than 140,000 barrels of oil per day, with a storage capacity of up to 1.6 million barrels.
  • There are 4 drill centers with 17 wells in total; 8 oil-producing wells, 6 water injection wells and 3 gas reinjection wells.
Person stands on FPSO in front of tools.Tool setup for the inspection


ExxonMobil’s affiliate in Guyana was looking for an inspection provider to support the Liza Phase 1 development by assessing internal corrosion and geometrical anomalies for 2 production loops from the Floating Production Storage and Offloading facility (FPSO) "Liza Destiny" in Guyana.

ROSEN was awarded the mission of designing, testing and finally completing the inspection of the 2 loops in Liza Phase 1.


Based on ExxonMobil’s needs (i.e., identify ID anomalies and corrosion), the in-line inspection (ILI) technology selected by ROSEN experts was RoCorr IEC (internal metal loss detection and sizing with eddy current). The specific pipeline design of both loops required a tailored solution with special capabilities: the ILI tool needed to be able to run through “Y” pieces and areas with high wall thickness and 3D bends, and it had to be able to withstand high pressures. ROSEN also qualified and supplied the cleaning pigs for the cleaning runs required for inspection.

The methodology used to design/modify the RoCorr IEC and cleaning tools is described in the workflow below:

  1. Concept of the project based on all the information gathered and ExxonMobil’s requirements.
  2. Design of all components required to run and pass through the specific pipeline design of both loops, including facility test.
  3. Manufacturing of all mechanical parts and casting of pull units.
  4. Assembly and tool preparation.
  5. Pump test in the loop test with the specific conditions of the pipelines.
Graphical representation of the workflow behind the project.Workflow behind the project

All five stages were completed successfully and on time according to the plan agreed with the client. During the last stage, the operator visited the ROSEN RTRC (ROSEN Technology and Research Center) in Lingen (Ems), Germany, to witness the pump test performed with the new designs of the cleaning tools and RoCorr IEC tool, customized for these pipelines. Both pump tests were completed satisfactorily.

Having all tools ready and tested, the equipment was mobilized and shipped to Guyana, where the inspection plan was then carried out. The cleaning/gauging tools were launched, and after the approval of the safe passage and proper degree of cleanliness, both loops were successfully inspected with the RoCorr IEC technology, obtaining the data with the quality expected to proceed with the evaluation and reports.

Thanks to our international experts’ efforts, planning and coordination, the execution of the project was flawless, even with operational changes and COVID-19 challenges, and the client was able to achieve an important milestone in their subsea flowlines integrity surveillance program.

For every challenge, ROSEN has a solution!


[1] https://corporate.exxonmobil.com/locations/guyana/guyana-project-overview

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