DEEPWATER CASE STUDIES
Australian deepwater plays
beckon offshore operators
Operators working offshore Australia continue to move for ward with plans to develop and produce oil and gas from fields in deepwater and remote areas. While a number of recent projects
offshore Australia have been located in relatively shallow waters, the Greater Enfield development project marks a notable milestone in the
country’s deepwater development.
It involves the development of the Laverda
Canyon, Norton over Laverda, and Cimatti oilfields offshore Australia. The fields are located
within the offshore Carnarvon basin, approximately 60 km ( 37 mi) northwest of Exmouth,
Western Australia. The Laverda accumulations are situated at a water depth of 550 m
( 1,804 ft), whereas the Cimatti accumulation
is situated at a water depth of 850 m ( 2,788 ft).
The project is owned by the joint venture
of Woodside Energy (60%) and Mitsui E&P
Australia (40%). Woodside Energy is the
operator for the project. The final investment decision for the project was made in
June 2016 and first production is anticipated
in mid-2019. The overall investment in the
project is estimated to be $1.9 billion.
The Laverda field was discovered in 2000,
whereas the Cimatti field was discovered in
2010. The Laverda field was first appraised
in 2011 by drilling the Laverda North- 1 well
at a water depth of 809 m ( 2,654 ft) and to total depth of 2,282 m ( 7,486 ft). It was further
successfully appraised by drilling the Laverda North- 2 well to a total depth of 2,300 m
( 7,545 ft), which discovered a gross interval
of 18 m ( 59 ft) of oil-bearing sands.
Another appraisal well, the Norton- 1, was
drilled in February 2012 at a water depth of
782 m ( 2,565 ft) and to a total depth of 1,718 m
( 5,636 ft). It encountered oil and gas and confirmed the easterly extension of the oil-bearing
sands discovered by the Laverda North- 2 appraisal well.
The Cimatti field was discovered in November 2010 by drilling the Cimatti- 1 well at
a water depth of 547 m ( 1,794 ft), and to a total depth of 2,424 m ( 7,952 ft). It intersected a
gross oil column of 15 m ( 49 ft).
The field was appraised in the same month
through the drilling of the Cimatti- 2 well at a
water depth of 547 m ( 1,794 ft), and to a total
depth of 2,460 m ( 8,070 ft). The well intersected a 7-m (23-ft) thick oil-bearing sand.
The project is estimated to hold proven and
probable (2P) reserves of 69 MMboe. The
development is planned to have six subsea
production wells and six water injection wells.
Production will be supported by subsea multi-phase booster pumps in the Laverda area and
gas lift in the Cimatti area.
These fields will be produced via a 31-km (19-
mi) subsea tieback to the Ngujima-Yin FPSO
which serves the Vincent oil field. Commissioned in 2008, the FPSO has an oil processing
capacity of 120,000 b/d.
The FPSO’s topsides, hull, and turret will
also be modified to accommodate the capacity
from the new fields. The vessel is connected to
the seabed, at a water depth of approximately
340 m ( 1,115 ft), using a disconnectable turret
The front-end engineering and design (FEED)
study for the project’s subsea production system
and the subsea multiphase booster pumps was
performed last year by OneSubsea, while the
FEED study for the subsea tieback system was
performed by Aibel Pte Ltd.
The Norton- 1 well was drilled by Diamond
Offshore’s Ocean America semisubmersible
drilling rig, with support provided by Farstad
Shipping’s Lady Caroline and Far Strait
anchor handling and supply vessels.
In July, Woodside awarded OneSubsea a
$300-million engineering, procurement, and
construction contract to supply a subsea pro-duction system and a dual multiphase boosting system for the project. The scope of contract includes six horizontal Spool Tree subsea
trees, six horizontal trees for the water injection system, six multiphase meters, a high-boost dual pump station with high-voltage
motors, umbilical, topsides, subsea controls
and distribution, intervention and workover
control systems, landing string, and installation and commissioning services.
OneSubsea has contracted Nexans for
the project’s umbilical and accessories. The
$24-million package will be Nexans’ first delivery to a project offshore Australia. The
umbilical will be installed in water depths
of up to 915 m ( 3,002 ft), and will comprise
both dynamic and static sections. A January
2018 delivery is anticipated.
Woodside awarded Aibel a contract for modifications on the Nguijma-Yin FPSO. This work
will involve modifications to the topsides, hull,
and turret, along with installation of a new custom water-flood module. Work was expected
to begin in July and advance toward a January
2019 completion date. •
The Greater Enfield development project will involve the development of six subsea production
wells and six water injection wells integrating subsea multi-phase booster pumps, tied back to the
Ngujima-Yin FPSO. (Image courtesy Woodside Energy)