Gene Kliewer • Houston
New depth record set
The new record depth for subsea completion of 9,356 ft (2,852 m) set by Shell at the Silvertip field part of Perdido in the Gulf of Mexico used an enhanced vertical deepwater tree system from FMC Technologies Inc.
To date, 321 total subsea installations are scheduled through 2012 and beyond according to ODS-Petrodata. Some 43 of them are in the US GoM, 50 in the Western Hemisphere excluding the GoM, 113 off northwestern Europe, 10 in the Mediterranean and Black seas, 59 off West Africa, and 37 in the Asia/Pacific region. The remainder was not identified as to location.
FMC’s overall scope of supply for the Perdido Area Development includes 17 subsea trees pressure rated at 10,000 psi, five subsea caisson separation and boosting systems, two subsea manifolds, topside and subsea controls, and related subsea equipment.
Other GoM
Murphy Exploration & Production Co. USA has ordered $23-million in subsea trees, control systems, and steel tube umbilicals for use in the GoM from Aker Solutions. Delivery of all components is scheduled for 2Q 2009.
Engineering design and project management will come from Aker Solutions’ office in Houston with manufacturing of most components at Aker Solutions’ subsea manufacturing center in Kuala Lumpur, Malaysia. Umbilicals will come from Aker Solutions’ facility in Mobile, Alabama. Offshore installation support will be provided from Aker Solutions’ service base in Houston.
North Sea
Subsea 7 has contracted Aker Solutions to supply steel tube umbilicals for Troll B gas development project in the Norwegian North Sea for NOK 100 million ($14 million). According to the agreement, Aker will supply 7.5 km (4.66 mi) of dynamic and static steel tube umbilicals in April 2010 from its Moss, Norway, facility. The umbilicals are destined for two subsea gas injection satellite wells south of the Troll B platform in 300 to 340 m (984 to 1,115 ft) water depth.
SRD has acoustically visualized the subsea in Frigg field of the North Sea as part of Total Exploration & Production’s decommissioning work. SRD did the survey under contract to Saipem UK’s Sonsub Division.
The operation involved the removal and disposal of pipelines within a 500-m (1,640-ft) radius of the platforms and was conducted from theNormand Cutter. There was also a requirement to smooth the original protective rock berms to remove hazards for subsequent trawling activities. SRD’s Subsea Visualisation System (SVS) provided real-time monitoring of the smoothing operation and was used for rapid assessment of the dispersal of material.
Bathymetry survey of the whole Frigg Field area, along with debris locations.
A pair of 240-kHz SVS sonar heads was used along with integrated heading, motion, and depth sensors. Seabed data was acquired in water depths of 100 m (328 ft) using both conventional multibeam and electronic transmit beam-steering.
Attention was focused on eight pipelines within a 500-m (1,640-ft) radius. These routes featured either rock berms covering the pipe or trenches where the pipe had been removed. In both cases, smoothing was required to reduce the severity of the slopes. The SVS produced terrain images displaying seabed gradients in color. The images highlighted where localized gradient values were outside the pre-determined limits.
There was also a requirement for a number of pipe ends to be buried to at least 1 m (3.3 ft). SVS was used for real-time comparison of historical pre-trenching data with actual post-trenching survey data. Using pipe burial information from an ROV-mounted pipe tracker, SRD imaged and quantified pipe burial depths.
After all smoothing, SRD conducted a bathymetry survey of the whole field to identify remaining debris.
At press time, testing was under way on the subsea raw seawater injection pumps destined for StatoilHydro’s Tyrihans field in the Norwegian Sea. Upon successful completion of testing, the pumps will be installed in 270 m (886 ft) of water some 31 km (19 mi) from the Kristin platform.
According to Aker Solutions, both the pump duty of 2.8 MW and the 31-km (19-mi) step-out will be new records for subsea pumps.
The pumps will intake 14,000 cm/d (almost 3.7 MMgal/d) of untreated seawater and inject this into the reservoir. The pumps drive the water into the ground between the oil reservoirs Tyrihans North and South. This plus gas injection is designed to give optimal pressure support in the reservoir and a higher degree of oil recovery. It is expected that the pumps alone will help increase production by 19 MMbbl of oil during the field’s lifetime.
StatoilHydro has a 58.8% interest in the Tyrihans field. Its partners are Total with 26.5%, Eni with 7.9%, and ExxonMobil with 6.75%.
Asia/Pacific
Woodside Energy has contracted Pöyry to provide flow assurance and related processing engineering services for the Pluto LNG project under construction on and offshore Western Australia.
Pluto will have one of the longest deepwater subsea tiebacks, running 17 mi (27 km) from the reservoir to the Pluto platform and then 112 mi (180 km) to the onshore LNG plant.
A portion of the work involves hydrate management using practices and technologies to address the various steady state and transient operating conditions expected.
Planned first gas is in late 2010. The A$12 billion ($7.76 billion) project will process gas from the Pluto and Xena gas fields in the Carnarvon basin.
