Pohokura Gas Field Project (Landfall)

Type of project: Gas Infrastructure

Client: Shell Todd New Zealand
Location: New Plymouth, North Island, New Zealand
Completed in: 2007

The Pohokura Gas Field Project involved the delivery of an exceptionally complex Horizontal Directional Drilling (HDD) shore crossing, setting a world record at the time for the longest HDD landfall, with a total drilled length of 1,850 metres.

The alignment commenced high on a 33‑metre coastal cliff and extended offshore beneath a rocky reef, presenting significant technical, geological and logistical challenges that pushed the boundaries of HDD capability.

Technical challenges and solutions

One of the key challenges was navigating highly varied geological conditions along the HDD alignment. In order to drill through the surface layers of pyroclastic boulders and cobbles, a steel casing was advanced approximately 146 metres using a 2,000-ton pneumatic hammer.

HDD plant and fluid management

Drilling operations were conducted using an American Augers DD1100 HDD rig, delivering 500 tonnes of push/pull capacity, and 136 kNm of torque.

At the time, it was the largest HDD rig in the Asia‑Pacific region and one of the five largest rigs globally, enabling precise steering and controlled drilling over the exceptional crossing length.

To manage drilling fluid returns and maintain hole stability, a centrifuge system was deployed to effectively remove ultrafine cuttings generated from the siltstone and mud layers.

Scope of works

HDI Lucas delivered the full HDD scope, including:

• Construction and maintenance of the launch pit and work areas;
• Execution of the HDD landfall drilling and installation works;
• Provision, transport and management of all consumables, materials and specialist equipment required to safely deliver the crossing.