Gas-condensate fields of the Taranaki basin, New Zealand

Abstract

Abstract The onshore Kapuni and offshore Maui gas-condensate fields contain New Zealand's only proven hydrocarbon reserves. The fields lie within the Taranaki basin in the west of the North Island. Kapuni, discovered in 1959, first produced in May 1970. Maui, 40 km offshore in 360 ft (110 m) of water, discovered in 1969, is not due to produce until October 1978. Production from both fields is from Eocene sandstone reservoirs within the coal-bearing Kapuni Formation which was deposited in a widespread coastal plain and fluviomarine environment. The original recoverable reserves of the Kapuni field are presently estimated at 460 million million Btu of dry gas (630 thousand million cu ft at 730 Btu/cu ft) and 34 million bbl of condensate. Production in 1973 averaged 46.3 million cf/d of gas (carbon dioxide content 43%) and 3500 b/d of condensate. With additional wells to be drilled in 1974, maximum deliverability will increase to 260 million cf/d of gas and 18 000 b/d of condensate so that 108-7 million million Btu (about 24% of the original reserve and two-thirds of the production) can be supplied as raw gas with its original carbon dioxide content to the New Plymouth power station during 1975–78 pending supply from Maui. Maui field reserves are estimated at 5730 million million Btu of dry gas (5590 thousand million cu ft at 1025 Btu/cu ft) with 161 million bbl of condensate and 51 million bbl of recoverable LPG. On production a maximum throughput of 750 million cf/d of gas and 20 000 b/d of condensate is envisaged. The gas will provide fuel for over 3000 megawatts of generating capacity in North Island power stations. Development of the field and associated processing and distribution facilities will be undertaken jointly by the Government (50%) and Shell, BP and Todd.