HDD cuts cost of Saudi pipe installation

Saudi Aramco has completed two novel pipelay assignments in the Arabian Gulf.

Offshore staff

DHAHRAN, Saudi Arabia --Saudi Aramco has completed two novel pipelay assignments in the Arabian Gulf. The work involved teams from the company's Oil and Gas Upstream Pipelines and Offshore Projects divisions.

The first achievement involved sections of pipelines between Abu Ali Island and the end of Berri Causeway.

The 3,200-m (10,499-ft) sections of the 24-in. (61-cm) crude pipeline and the 30-in. (76-cm) water injection line were laid 32 m (105 ft) beneath the seabed using horizontal directional drilling (HDD) techniques.

Saudi Aramco's other main accomplishment was its first application of HDD technology to install a pipeline from the shoreline into the sea. The 30-in. water injector line included an underground section stretching from the edge of Abu Ali Island to an exit point more than 1,500 m (4,921 ft) into the Berri offshore oil field.

HDD allows pipes to be installed without the need for trenching or dredging. The first stage of the process involves drilling a pilot hole between two ground entry points, using electronic positioning/steering instruments to guide the drill head along the required path.

Once this hole is completed, a series of reaming passes are expected to expand the size of the hole using progressively larger tools. Finally, the pipeline is pulled through the newly formed tunnel.

For this project, HDD brought the added advantage of avoiding environmental disturbance associated with conventional seabed preparation methods. This was a major concern because of the sensitivity of the local marine environment at Berri and Abu Ali Island, where there are several endangered species of coral.

Use of HDD also saved Saudi Aramco an estimated $54 million at Berri, due to the locally shallow seabed conditions. Otherwise extensive access dredging would have been needed merely to reach the pipeline dredging zone.

Drilltec and Digital Connection managed the HDD program on behalf of main contractors Global Al-Rushaid Offshore and Al-Robaya.

05/27/2009

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