Greg Donnelly - Subsea 7
Port Isabel, on the Texas coast close to the Mexican border, is the site for Subsea 7’s new US pipeline spoolbase. The facility covers 58 acres (23.5 ha) and is 5,000 ft (1,524 m) long, including a 4,000-ft (1,219-m) stalk rack and 1,000-ft (305-m) fabrication building. It will enable the company to offer an enhanced deepwater rigid pipelay service in the North America region.
The spoolbase will be able to fabricate and store individual pipe stalks up to 20-in. (50.1-cm) diameter, 16-in. (40.6-cm) steel plus 4-in. (10.2-cm) insulation coatings, in lengths up to 4,000 ft (1.2 km), with possible future expansion of up to 5,905 ft (1.8 km). It also will be equipped to weld any steel material from traditional carbon steel to duplex and clad pipe. Furthermore, the base will be able to complete fabrication of plastic lined pipe-in-pipe lines, regular steel pipe-in-pipe, and steel catenary risers (SCRs). In full production, the base will be able to hold around 19,841 tons (18,000 metric tons) of pipe stalks.
Aerial view of Subsea 7’s new spoolbase in Port Isabel, Texas.
Work on the site began in earnest in 2008, in the middle of the region’s wettest summer for many years. Port Isabel was also the recipient of one of three major hurricanes to make landfall on the Gulf Coast during the year, although this did not materially slow progress.
Subsea 7 chose the site for several reasons: its central Gulf of Mexico location, exceptional access to a skilled and committed workforce, the deepwater port, and excellent connectivity to road, sea, and air transportation.
The spoolbase is designed to offer significant efficiencies. A 500-ft (152.4-m) quay allows pipelay vessels to execute simultaneous pipe-spooling and mobilization of equipment, and also provides support to the company’s fleet of construction support vessels. And the location in southern Texas is convenient for projects in the new deepwater acreage in the US and Mexican sectors.
The fabrication building houses the primary firing line which is optimized for double joint production. This line, with 12 stations at 80-ft (24.3-m) intervals, uses a 50-ton (45.4-metric ton) hydraulic pipe pusher system to index pipe through the fabrication process and onto stalk storage racks. The fabrication line will feature automatic, semi-automatic, and manual welding.
TheSeven Oceans during in-field operations on the Blind Faith project.
By mid-fall of 2008, the pipe stalk rack was virtually complete. The two main fabrication buildings had been delivered and work on the foundation slabs was ongoing. The quay-side contractor had mobilized equipment to site, dredging work had started, and the project was on schedule.
Like all new Gulf of Mexico building projects, this facility is working to hurricane region building codes, so buildings are designed to withstand up to 130 mph [209 km/hr] winds. Another major challenge with hurricanes is the storm surge which produces significant coastal flooding.
In fact, during Hurricane Ike, which hit the Greater Houston area in 2008, the sea rose by 20 ft [6.1 m) and this caused widespread damage to buildings and property close to the water. So this spoolbase has installed as much of the electrical equipment as possible off the floor to prepare for the possibility of two or three feet of water coming in.
The first construction phase also provided evidence of the capacity of the navigation channel serving the spoolbase. When the Port Isabel location was first identified as a potential site for the spoolbase, there were reservations that the channel might be too narrow for vessels such as the 157-m (515-ft) long pipelayerSeven Oceans. But when a 700-ft [213-m] Mexican bulk carrier brought in crushed aggregate with ease, any hesitation evaporated.
Over the past few months, the project team had to ensure that land at Port Isabel meets environmental, regulatory, and other business conditions. This has involved meetings with the port director, the mayor of Port Isabel, and other local officials.
Reaction from the Port Isabel community to the new spoolbase has been overwhelmingly positive, particularly as Subsea 7 is helping to support the local economy hurt by downturns in other industries. The spoolbase is expected to have a positive economic impact on the area, generating between 60 and 80 jobs in the long term.
“We have good supporting marine infrastructure nearby which is gearing up quickly to work with us,” says the company. There is a local university that we can work with to offer specialized training and we can recruit locally from a rich and diverse pool of talent.”
The spoolbase already has its first contract: fabrication of 36 mi (58 km) of 8-in. (20.3-cm) pipeline for Marathon’s Droshky field development south of Louisiana, to be laid by theSeven Oceans. This vessel was designed and built for deepwater pipelay and heavy construction. It is fitted with a main reel capable of carrying 3,500 tons (3,175 metric tons) of rigid steel pipe and a 400-ton (363-metric ton) tensioner system allowing installation of pipeline in the deep waters of the Gulf of Mexico.
Droshky is some 90 mi (145 km) south of Houma, Louisiana, and will be a subsea tieback to the Shell Bullwinkle platform. The project is a life extension of Bullwinkle, where production has declined in recent years. It also is Marathon’s first GoM project in 14 years, as well as its first ever in the deepwater sector. The development will comprise installation of dual insulated 8-in. (20.3-cm) flowlines creating a pigging loop which will initiate adjacent to the Droshky six-slot manifold at Green Canyon block 244 with pipeline end terminals (PLETs) and terminate with flowlines pulled in.
Ian Cobban, vice president of the North America region comments: “I think in some places we are still perceived as an umbilical and installation specialist. Now, with the $30 million investment we’ve made at Port Isabel, we are building on our vision to become the subsea partner of choice in our sector and are fully committed to the Gulf and entire North American region.
“With the extensive current and predicted volumes of oil and gas production in the North American region being delivered through subsea facilities, our ability to install high quality deepwater pipelines will give us an important competitive edge, allowing us to expand on the significant infrastructure that we have already established in the United States.”
