TOP 5 PROJECTS
Liwan marks first-ever deepwater
gas development offshore China
Three felds share subsea production system
Husky’s Liwan gas project is the frst deepwater gas development offshore China. The project, in block 29/26, delivered frst production this year, approximately seven years following
its discovery, and is one of the fastest developments in the world for a large-scale gas
discovery in deepwater.
It is in the South China Sea 300 km (186
mi) southeast of the Hong Kong Special Administrative Region. Liwan consists of three
natural gas felds: Liwan 3-1, Liuhua 34-2,
and Liuhua 29-1, which share a subsea production system, subsea pipeline transportation, and an onshore gas processing plant.
Liwan’s current nine deepwater wells are
in approximately 1,200 to 1,500 m ( 3,936 to
4,920 ft) of water about 75 km ( 47 mi) from a
shallow-water platform, which in turn is connected by pipeline to the onshore Gaolan
Gas Terminal. The terminal extracts condensates and liquids, then compresses and
moves the Liwan gas to commercial markets in mainland China. Gas production is
covered by a long-term sales contract, while
condensates and natural gas liquids (NGLs)
such as propane and butane will be sold
Husky holds a 49% interest in the pro-
duction-sharing contract and operates the
deepwater infrastructure, including the nine
subsea wells, deepwater fowlines, control
systems and manifolds, and the MEG unit on
the shallow-water platform. Cameron supplied
subsea trees, three production manifolds, con-
nectors, controls, and the MEG modules.
CNOOC Ltd. holds 51% interest, and operates the shallow-water facilities, including
the platform, the 260-km (132-mi) long subsea pipeline to shore, and the onshore gas
Since start-up, Liwan gas sales have risen
to 200-220 MMcf/d, and plans are to complete a second 22-in. pipeline from Liwan 3-1
to the shallow-water platform. Plans also are
in the works for Liuhua 34-2 feld to be commissioned, subject to fnal approvals, and
the partners are assessing opportunities for
the Liuhua 29-1 feld with a view to achieve
frst production in 2018.
Under the $6.5-billion frst-stage program,
Liwan 3-1 is expected to produce about 250
MMcf/d ( 7. 1 MMcm/d), and increase to
about 300 MMcf/d ( 8. 5 MMcm/d). Initial
sales of condensates and natural gas liquids
from the feld are expected to reach 10,000-
Liuhua 34-2 was scheduled to be tied into
the Liwan infrastructure during the second
half of the year. Liuhua 29-1 is scheduled for
tieback during 2016-2017.
DeepOcean UK did 174 km (108 mi) of
pipeline trenching on behalf of China Offshore Oil Engineering Corp. (COOEC) in
early 2012. DeepOcean used multi-purpose
offshore vessel Volantis and UT- 1, a free-fy-ing jet trencher. The pipeline connects the
gas feld’s central platform to the shore at
CNOOC’s Gaolan gas plant.
Other milestones included installation of
the 30,000-metric ton ( 33,069-ton) topsides
on the shallow-water jacket; construction of
the onshore gas terminal; and completion of
all nine subsea deepwater production wells.
Husky Energy installed 14 “frac-pack” lower
completions, 10 subsea horizontal trees, and
seven upper completions between June 2011
and January 2013. On average, the lower completions, tree installation, and upper completions required, 12 days, 2 days and 24 days,
respectively. The water depth ranged from 650
m ( 2,132 ft) to 1450 m ( 4,756 ft).
Husky Oil China Ltd. awarded a $25-mil-
lion subsea and well testing contract to a
China-based joint venture between Expro
and China Oilfeld Services in support of
Phase II. The three-year contract includes
a surface clean-up and fow-back package.
The JV, CETS based in Shekou, installed
surface equipment to handle the expected
high fow rates. Design also called for short-
notice detach in the event of a typhoon.
Technip was contracted for the shallow-
water portion, including installation of 160 km
(100 mi) of 30-in. export oil/gas two-phase pipe-
line from the platform to a water depth of 70 m
(230 ft). Technip used the Global 1201 pipelay
vessel. Saipem won the contract to install the
deepwater portion of the pipeline.
WorleyParsons was awarded the contract
to carry out FEED studies at the feld. This
included estimation and planning of the proj-
ect. WorleyParsons also prepared engineer-
ing, procurement, and construction tenders
for different packages. •
Subsea & Seismic
Schematic of subsea tieback arrangement at Liwan 3-1. (Image courtesy CNOOC Ltd.)