PT Saipem Indonesia - HDD shore approaches for BP Tangguh project

PT Nacap Indonesia, part of the Nacap pipeline group of companies, has been awarded a contract by PT Saipem Indonesia for Horizontal Directional Drilling and Onshore Pipelines and Cables Installation, as part of the BP Tangguh GPF Pipelines and Cables Project. Project Overview The Tangguh development is situated in the "Birds Head" area of Papua (Irian Jaya), Indonesia, and will exploit the natural gas reserves located in Berau Bay Area, about 3,000 km east of Jakarta. The Tangguh GPF production capacity will support an LNG facility on the south shore of the Bay. Initially gas supply will come from the main Vorwata (VR) field. The Gas Production Facilities (GPF) offshore Construction Work will consist of two platforms as the initial development. The platforms, VR-A and VR-B, will be located approximately 20 km from the south shore of the Berau Bay and will be in approximately 57 m water depth.
	Design conditions include: High gas temperatures, corrosive gas, strong tidal currents, low visibility water, remote location, and earthquakes with associated soil liquefaction. The platforms will be normally unattended installations (NUIs) with no topsides processing facilities. The GPF onshore Construction Work, called the OSF, will consist of landfall receiving facilities that will consist of two pig receivers and associated Work, GPF operations shore base, control room and share telecommunications facilities. Two new sub-sea pipelines (one per platform) will transport multiphase gas from the platforms to a landfall receiving facility. The pipelines will be 24" in corrosion resistant alloy (CRA). Two new submarine cables from each platform to the onshore plant will transmit power and enable communication between the LNG plant (onshore) and platforms (offshore). The third cable will be installed between the platforms to form a closed loop.
PT Nacap Indonesia will install the landfall crossing for the two 24" gas pipelines and two 10" cable ducts, by four separate HDD's, each measuring approximately 1,450 m length. Nacap will also construct the onshore pipeline and cable sections from the landfall tie-in points to the LNG facility. In addition to the geographical remoteness of the project location, other challenging site conditions include: Approximately 4 m daily tidal variation in Berau Bay. High On-bottom and surface currents generated by tidal variations. Current speed up to 2.0 m/s.  Low in-water visibility (0 - 3 m).  High variable seabed type (sand waves, soft clay, very stiff clay and unconsolidated silts and sand).   Rough seabed, with areas that could liquefy during seismic events.   No local infrastructure.