Pipe installation in Papua New Guinea

Once completed, the Papua New Guinea (PNG) LNG Project will comprise an integrated development of the Hides, Angore and Juha gas fields, as well as associated gas from the Kutubu, Agogo, Gobe and Moran oil fields in Papua New Guinea. The project involves a two-train, 6.9 million tonnes per annum LNG processing facility and gas will be transported to the LNG plant near Port Moresby through more than 850 km of large diameter pipeline. Delivery of LNG is scheduled to commence in 2014.

The offshore pipeline

The DN900 diameter offshore pipeline has been constructed from carbon steel and is coated with concrete to ensure stability on the seabed.

The pipeline commences at the Omati River landfall and follows the river for approximately 24 km past Goaribari Island to the open sea. The pipeline then crosses the Gulf of Papua to the Caution Bay landfall at the LNG plant site near Port Moresby. The route was selected to avoid coral reefs and environmentally sensitive areas.

Construction of the offshore pipeline was undertaken by Italian company Saipem and overseen by a multi-disciplinary Esso Highlands Limited (EHL) Project team.

The pipeline was laid in two sections over nine months using two pipelay vessels. The Castoro-10 was used for the shallow water section of the pipeline and the Semac-1 was used for the deepwater section. The two sections were connected using a procedure called an above-water-tie-in.

“The tie-in joined and welded the shallow water and deepwater pipeline ends together to form one continuous pipeline. The single continuous pipeline was then lowered back into the water once the tie-in was complete, concluding the installation stage of the offshore pipeline,” said EHL Offshore Pipeline Installation Manager Weng-Kong Chee.

According to Mr Chee, pipelay operation efficiency was improved by the use of double joint linepipe, which effectively halved the number of joints for welding in the firing line. In addition, Mr Chee observed that the use of automatic welding and automatic ultrasonic weld testing further improved production efficiency.

Construction of the offshore pipeline was completed in July 2012, and by November 2012, pre-commissioning activities, including hydrotesting and drying, were complete for the entire pipeline.

The onshore pipeline

The onshore pipeline system consists of over 450 km from the PNG Highlands to the landfall at the Omati River. The scope of work includes:

    • 292 km, DN800-DN850 diameter LNG gas line, which travels from the Hides gas conditioning plant (HGCP) to the Omati landfall;

 

    • 109 km, DN200 diameter condensate line, which runs from HGCP to Kutubu;

 

    • Approximately 60 km of additional gas gathering flowlines and injection lines that are up to DN550 in diameter;

 

    • Approximately 12 km of DN250-DN300 diameter laterals, which connect the LNG gas line to existing oil facilities; and,

 

  • Fibre optic and power cables buried alongside various pipelines.

Approximately 40,000 joints of pipe are being used in this mammoth pipe laying effort, which was 55 per cent complete in October 2012 with hydrotesting done on approximately 145 km of pipeline.

Challenges in construction

EHL identified the following factors as key challenges to the pipe installation process:

    • Geotechnical hazards, such as seismic faults;

 

    • Densely forested terrain including steep slopes, landslides, liquefiable soils, karsts and swamps;

 

    • Hydrological conditions including rainfall and flooding;

 

    • Sensitive fauna and flora;

 

    • Approximately 15 major water crossings (including four horizontal directional drills) and over 200 minor water crossings;

 

    • Approximately 23 seismic fault crossings (active and inactive); and,

 

  • Elevations of up to 2,770 m to sea level.

According to EHL Onshore Pipeline Manager Suresh Batra, construction challenges were overcome by evaluating geohazards and implementing risk mitigation measures; strict route selection criteria; selecting pipe that was specifically manufactured to withstand movements at the seismic fault crossings; undertaking extensive aerial and ground pipeline surveys; and, choosing contractors and subcontractors with a proven track record.

Local involvement in pipeline construction

With construction activity at Komo airfield, the HGCP and the LNG plant site increasing, the project is relying on landowner companies (Lancos) to supply services such as camp maintenance, catering, security, equipment hire and recruitment.

EHL Lead Media and Communications Adviser said a key objective of the project’s national content plan is to develop and enhance the skills of the PNG workforce to meet the demands of construction activities and for longer term operations roles.

“To date, more than 10,000 Papua New Guineans have received training for construction and operation roles delivered through 6,000 courses in over 1.4 million hours of training. This includes training provided through dedicated facilities such as the Juni Construction Training Facility, where the third intake of trainees graduated with their Australian Quality Training Framework standard Certificate Level II in General Construction and Civil Construction,” said Ms Arnold.

In addition, Ms Arnold said the project and its contractors have engaged with Papua New Guinean communities with the aim of building positive relationships based on trust, mutual understanding and collaboration.

“To date, the project has completed more than 760 formal engagements, interacting with almost 28,200 community members. This is in addition to more than 1,220 people reached through informal engagements,” said Ms Arnold.

“Key topics discussed with communities include safety near the pipeline right of way, pedestrian safety, hygiene in schools, drilling operations, environmental awareness, pre-commissioning activities and general project updates.

“Through the PNG LNG Project, Esso Highlands is now very much a part of the Papua New Guinean community and is working hard to remain a valued member of the community within which they operate.”

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