HOUSTON -- Subsea 7 has completed installations for Marathon’s Droshky development in the Gulf of Mexico. This was the first project to be delivered through Subsea 7’s new North American spoolbase at Port Isabel, Texas.
The project, managed from the company’s Houston office, involved fabrication and installation of two 8-in. (20.3-cm) flowlines with a total length of 58 km (36 mi) for Droshky.
Pipeline assembly was executed at the spoolbase between June and October 2009. Offshore operations started afterwards following the arrival of the vessel Seven Oceans to begin spooling the first of three pipelay campaigns.
Subsea 7 also performed for the same project the engineering, fabrication, and installation of two 580-m (1,900-ft) 8-in. risers, four termination pipeline end structures, and two initiation pipeline end manifolds. The scope included metrology, fabrication, and installation of three rigid jumpers as well as pre-commissioning of the entire Droshky pipeline system
The Seven Oceans’ work scope was split into three campaigns due to the length of the two pipelines. The pipelay and construction vessel Skandi Neptune also was brought in to install the jumpers.
Droshky, in a water depth of 900 m (2,950 ft), has been developed with five subsea wells exporting production through two 29-km (18-mi) insulated pipelines. The development constitutes a life extension of the Bullwinkle platform, where output has decline steadily in recent years. Droshky is also Marathon’s first new Gulf of Mexico development in 14 years and its first ever deepwater project in the sector.
The Port Isabel spoolbase was opened last July in Port Isabel, around 11 km (7 mi) from Brownsville. It is 1.5 km (0.9 mi) in length, including a 1.2-km (0.75-mi) stalk rack and a 0.3-km (0.18-mi) fabrication building. The base employs up to 100 people when working at normal capacity.
The $30-million facility is equipped to weld any steel line pipe material from traditional carbon steel to duplex and clad pipe. In addition, the base can complete the fabrication of plastic-lined pipelines, pipe-in-pipe systems, and steel catenary risers. At full production, the base can hold 18,000 metric tons (19,841 tons) of pipe stalks.