Pohokura

Pohokura Gas Field Profile

Location and Geology

The Pohokura Gas Field is located offshore in the north-east of New Plymouth, within the Taranaki Basin, close to the Methanex Motunui site near Waitara, New Zealand. The field is situated in shallow water, approximately 35 meters deep, in Block PMP 38154 (also referred to as block 174E38/32).

The Taranaki Basin includes reservoirs ranging from Paleocene to Pliocene ages. The Pohokura field is a gas-condensate field located on a low-relief anticline, spanning an area of 16 kilometers long and 5 kilometers wide, at a depth of about 3,600 meters.

Discovery and Drilling

The Pohokura field was discovered in March 2000 by Fletcher Challenge Energy with the first offshore well, Pohokura-1, which penetrated a 130-meter gas column and found 17.6 million standard cubic feet per day (mmscf/d) of gas. The Pohokura-2 well, drilled in the central part of the structure, penetrated a 115-meter gas column and flowed 35.3 mmscf/d during a drill stem test.

Additional appraisal wells, including Pohokura-03 and Pohokura South-01B, were drilled between September 2002 and January 2003. Shell acquired the assets of Fletcher Challenge Energy in 2001 and subsequently drilled several wells from both onshore and offshore locations.

Ownership and Operation

The Pohokura field is operated by Shell Todd Oil Services (STOS), although the operational responsibilities have transitioned to OMV New Zealand Ltd. The field is owned by OMV (26%), Shell Exploration NZ (30%), Shell (Petroleum Mining) (18%), and Todd Pohokura (26%).

Reserves

The Pohokura field is estimated to contain significant reserves, including 884 petajoules (PJ) of natural gas and 44 million barrels (mmbbls) of condensate. It is one of the largest gas condensate fields in New Zealand and contributes approximately 40% of the nation’s natural gas production.

Field Development

The $1 billion Pohokura development project was completed in June 2008. The field was developed in two stages. The first stage involved drilling three development wells from an onshore site into the southern end of the field, which was completed in August 2006. The first gas was fed into the North Island network in September 2006. Initially, six wells were planned, but it was later determined that five wells would be sufficient to extract the reserves.

The second stage of development involved the offshore section, using an Ensco-56 jack-up rig to place the offshore platform and topsides. Technip was contracted to supply and install flexible lines, umbilicals, and the wellhead platform for the field. The offshore platform and the onshore production station are remotely controlled from the New Plymouth offices of Shell.

Field Infrastructure

The infrastructure for the Pohokura field includes a wellhead platform, a subsea pipeline connecting the wellhead platform to the coast, and an onshore gas plant. Technip is responsible for the supply and installation of a 7.25 km long, 11.5-inch diameter flexible pipeline and a 9.2 km long umbilical and service line.

Production

The Pohokura conventional gas field has recovered 74.56% of its total recoverable reserves as of recent data. Peak production was achieved in 2012, and based on economic assumptions, production is expected to continue until the field reaches its economic limit in 2049. The field currently accounts for approximately 16% of New Zealand’s daily natural gas output.

Environmental and Regulatory Compliance

The operation of the Pohokura field is subject to compliance monitoring under the Resource Management Act (RMA) in New Zealand. The Taranaki Regional Council is responsible for monitoring the site to ensure environmental and regulatory compliance.

In summary, the Pohokura Gas Field is a significant natural gas and condensate field in New Zealand, operated by OMV New Zealand Ltd, with substantial reserves and infrastructure, contributing significantly to the country's energy production.