Kapuni is the oldest producing gas-condensate field in New Zealand, and this mature onshore field is surpassed in original size only by the offshore Maui field.

The field is held as a 50:50 Joint Venture between Shell (Petroleum Mining) Co. Ltd and Todd Petroleum Mining Company Ltd and is operated by Shell Todd Oil Services Ltd, also owned equally by Shell and Todd.

Field Location

The Kapuni field is located in the shadow of Mount Taranaki, near the small Kaponga township, some 65 km south of New Plymouth, and 10 km west of Eltham.

Sixteen Kapuni field wells are distributed around the surrounding farmland on nine well sites and gas, condensate and water production are fed by underground pipelines from these well sites to the Kapuni Production Station for processing.

Field History

The Kapuni gas-condensate field was discovered (Kapuni-1) in 1959 by a Joint Venture consisting of Shell (37.5%), BP (37.5%) and Todd (25%). Field appraisal took place in 1962-1963 with the drilling of three additional wells Kapuni 2 to 4.

The gas is located in the Mangahewa formation, some 3400-3800m below surface, in a sequence of sand, shale, coal and siltstone layers of variable quality, which form a large anticlinal structure sealed by the Otaraoa marine mudstone. The main producing intervals are located in the K1 and K3 intervals, but several sub-units with limited vertical connectivity are recognised within these main units. Field connectivity is also influenced by several in-field faults - especially the NW–SE running Kaponga fault zone.

Due to the high carbon dioxide (CO₂) concentration of the gas (40%), which requires special processing, and the lack of a natural gas infrastructure at the time, it took until 1967 before a gas market was established with the Crown and a gas purchase contract negotiated and executed.  The field subsequently came onstream in 1970.

The Kapuni discovery was a landmark event that had commercial significance for New Zealand. It launched a new era that saw consumers taking advantage of gas as an efficient and low-cost energy source for industrial and domestic use.  Kapuni’s success also led to the development of Taranaki’s energy infrastructure. 

Production from Kapuni peaked in the mid-late 1970’s at ca. 70 PJ/annum as part of the pre-Maui development of the gas market (in particular Kapuni gas fed New Plymouth Power Station for electricity generation). Once Maui came onstream in 1979, and Kapuni gas sales reduced to ca. 20 PJ/annum, the surplus field deliverability was used for a gas re-injection scheme to accelerate condensate production.

During the 1980’s and 90’s, a number of additional Kapuni infill/appraisal wells were drilled and hydraulically fractured to maintain field deliverability and test previously untapped zones.

In 1991 BP decided to exit exploration and production activities within New Zealand and sold their Kapuni field share to the remaining two Joint Venture partners, with the result that Shell and Todd shares became aligned at 50% each.

In the mid 1990’s,  Todd was extremely active in the gas market, which resulted in new gas supply contracts to the 70 MW Fonterra/Todd Energy co-generation plant located at Whareroa near Hawera (1996) and Taranaki By-Products plant located near Okaiawa in South Taranaki (1999).

Due to the natural decline in field deliverability, gas re-injection ceased in 2001. Since that time Kapuni has seen a high number of well entry related activities over the last few years, with recompletion workovers, additional perforations, water shut-offs, hydraulic fractures, and the drilling of a flank appraisal well (KA-16). Studies to asses further development opportunities are ongoing.

Field Facilities

Kapuni facilities currently consist of 16 wells located on nine well sites around the centrally located Kapuni Production Station. Low Temperature Separation units are installed on the well sites to separate the gas from the liquids (condensate and water) and pre-condition the gas.

Via separate pipeline gathering systems, gas and liquids are transported to the Kapuni processing plant, where the bulk of the gas is diverted, without significant further treatment, for sale into the NGC owned Gas Treatment Plant. NGC removes CO₂ from the gas and also recovers liquefied petroleum gas (LPG) and natural gasoline products. The in-field gas gathering system also feeds the pipeline to the co-generation facilities at the Fonterra dairy plant in Whareroa.

The liquid streams separated by the well sites facilities are treated in the Kapuni Production Station, which involves separation and stabilisation of water and condensate phases. The water is disposed of via a water injection well, while the condensate is transported by a dedicated cross-country pipeline to Port Taranaki in New Plymouth.  From there it is exported by marine tankers to refining destinations.