World Petroleum Resources Project

Assessment of Undiscovered Oil and Gas Resources of the 

Cretaceous-Tertiary Composite Total Petroleum System, 

Taranaki Basin Assessment Unit, New Zealand

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2012–3139

January 2013 Printed on recycled paper

Introduction

The U.S. Geological Survey (USGS) World 

Energy Resources Project conducts assessments of 

the potential for undiscovered, technically recoverable oil and natural gas resources of the world, 

exclusive of the United States. As a part of this 

program, the USGS recently completed an assessment of the conventional undiscovered resources of 

the Cretaceous-Tertiary Composite Total Petroleum 

System (TPS), Taranaki Basin Assessment Unit 

(AU), onshore and offshore New Zealand (fig. 1). 

The TPS and AU boundaries are coincident and will 

be referred to as the AU. Potential unconventional 

resources such as shale oil and coalbed methane 

were identified but not assessed. This assessment 

was based on data from oil and gas exploration 

wells, production data, and published geologic, 

seismic, and geochemical reports.

The Cretaceous-Tertiary Composite Total 

Petroleum System and Taranaki Basin 

Assessment Unit

The Cretaceous-Tertiary Composite TPS and 

Taranaki Basin AU include an area of approximately 153,000 square kilometers (km2

). The TPS 

and AU boundaries are coincident and will be 

referred to as the AU. The offshore portion of the AU 

makes up approximately 80 percent of the total area. 

Water depths range from 0 to 1,500 meters. The AU 

includes Cretaceous and Tertiary rocks in all or part 

of the Taranaki, Wanganui, and Deep-Water Taranaki 

Basins (fig. 1). 

Situated on the Australian tectonic plate, the AU consists 

of an onshore and offshore eastern graben complex and an 

offshore western stable platform. The graben complex and 

stable platform developed during Jurassic and Late Cretaceous–

Paleogene rifting events between Australia and New Zealand that created a rift sag basin and the Tasman Sea. The 

Late Cretaceous–Paleogene rifting was followed, from 35 to 

24 million years ago (Ma), by a relatively continuous period of 

regional compression and initiation of subduction of the Pacific 

plate. Collision of the Australian and Pacific plates resulted in 

the Australian plate overriding the Pacific plate on North Island 

and the Pacific plate overriding the Australian plate on South 

Island creating a plate inversion zone between the North and 

South Islands. The southernmost portion of the AU, between 

Christchurch

Wellington

170° 175°

35°

40°

45°

AUSTRALIA

ANTARCTICA

NEW

ZEALAND 

Area of map

TASMAN SEA

PACIFIC OCEAN

New Zealand_FS_Fig1.ai

EXPLANATION

Taranaki Basin AU and

 Cretaceous-Tertiary 

 Composite TPS 

NORTH ISLAND

SOUTH ISLAND

Deep-Water 

Taranaki Basin

Wanganui Basin

Taranaki

Basin

0 100 200 KILOMETERS

0 100 200 MILES

Auckland

Figure 1. Assessed area of New Zealand was defined as a single composite 

assessment unit (AU), Taranaki Basin AU 30310101 (outlined in red). TPS, total 

petroleum system.

The Cretaceous-Tertiary Composite Total Petroleum System coincident Taranaki Basin Assessment Unit was recently assessed for 

undiscovered technically recoverable oil, natural gas, and natural gas liquids resources as part of the U.S. Geological Survey (USGS) 

World Energy Resources Project, World Oil and Gas Assessment. Using a geology-based assessment methodology, the USGS 

estimated mean volumes of 487 million barrels of oil, 9.8 trillion cubic feet of gas, and 408 million barrels of natural gas liquids.
the North and South Islands, is part of the plate inversion zone. 

Back-arc extension related to subduction started approximately 

4 Ma and continues today.

The source rocks include Cretaceous and Paleogene marine 

and lacustrine shales and mudstones and Cretaceous and possibly Jurassic coals. Oil and gas generation occurred as early as 

Late Cretaceous in the deep-water part of the AU (Deep-Water 

Taranaki Basin) (Uruski and Warburton, 2010). Due to a varied 

burial history, generation has continued intermittently in different parts of the AU throughout the Cenozoic and is ongoing 

today in parts of the AU. The Taranaki Basin is filled with as 

much as 9 km of sediments. Maximum burial depth occurred 

during late Miocene in much of the basin. Migration is primarily along fault zones and into adjacent reservoirs.

Cretaceous and Tertiary reservoir rocks and potential reservoir rocks include turbidites, carbonates, alluvial sandstones, 

and volcaniclastics. Traps are primarily structural. Collisionrelated late Tertiary tectonics created three primary structural 

trap types—faulted anticlines, overthrusts, and tilted fault blocks 

(Crown Minerals, 2011). Seals are primarily shales and mudstones. Production is mainly from sandstones of the Eocene 

Kapuni Group and Oligocene Otaraoa Formation. There are 

eight discovered oil accumulations and twelve gas accumulations 

with a grown size (maximum expected volume of production) 

greater than the 5 million barrels of oil equivalent minimum 

assessed size (IHS Energy, 2010). Two fields, Kapuni and Maui, 

presently account for over 80 percent of New Zealand’s gas 

production and condensate (Crown Minerals, 2011). The Kapuni 

and Maui fields formed in faulted anticline traps.

Resource Summary

The Cretaceous-Tertiary Composite TPS, Taranaki Basin 

AU, was assessed for undiscovered technically recoverable oil, 

natural gas, and natural gas liquids resources. Using a geologybased assessment methodology (U.S. Geological Survey World 

Energy Assessment Team, 2000), the USGS estimated mean 

volumes of 487 million barrels of oil, 9.8 trillion cubic feet of 

gas, and 408 million barrels of natural gas liquids.

References Cited

Crown Minerals, 2011, New Zealand petroleum basins: New 

Zealand, Crown Mineral Estate, Ministry of Economic 

Development, accessed January 07, 2013, at http://www.

nzpam.govt.nz/cms.

IHS Energy, 2010, International petroleum exploration and production database [current through December 2010]: Available from 

IHS-Energy, 15 Inverness Way East, Englewood, CO 80112.

Uruski, C.I., and Warburton, J., 2010, Seismic evidence for active 

petroleum systems and charge history; PEP 38451 deep-water 

Taranaki Basin, in 2010 New Zealand petroleum conference: 

Conference Proceedings, Crown Minerals, Ministry of Economic Development, Wellington, New Zealand, 1 CD ROM.

U.S. Geological Survey World Energy Assessment Team, 2000, 

U.S. Geological Survey world petroleum assessment 2000—

Description and results: U.S. Geological Survey Digital Data 

Series DDS–60, 4 CD ROMS.

Total petroleum systems

(TPS) 

and assessment units (AU) 

Field

type

Largest

expected

mean

field size 

Total undiscovered resources

Oil (MMBO) Gas (BCFG) NGL (MMBNGL)

F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 F5 Mean

Cretaceous-Tertiary Composite TPS

Taranaki Basin AU Oil 53 269 464 781 487 310 546 925 572 6 12 20 12

Gas 1,011 4,895 8,797 15,036 9,225 209 377 646 396

Total conventional

 resources 269 464 781 487 5,205 9,343 15,961 9,797 215 389 666 408

[MMBO, million barrels of oil. BCFG, billion cubic feet of gas. MMBNGL, million barrels of natural gas liquids. Results show fully risked estimates. For gas fields, all 

liquids are included under the NGL (natural gas liquids) category. Undiscovered gas resources are the sum of nonassociated and associated gas. F95 represents a 95-percent 

chance of at least the amount tabulated. Other fractiles are defined similarly. Largest expected oil field size is in MMBO; largest expected gas field is in BCFG. TPS, total 

petroleum system; AU, assessment unit. Gray shading indicates not applicable] 

Table 1. Taranaki Basin AU Assessment Unit results .

Table 1. Taranaki Basin Assessment Unit assessment results.

[MMBO, million barrels of oil; BCFG, billion cubic feet of gas; MMBNGL, million barrels of natural gas liquids. Results shown are fully risked estimates. For gas 

fields, all liquids are included under the NGL (natural gas liquids) category. Undiscovered gas resources are the sum of nonassociated and associated gas. F95 represents a 

95-percent chance of at least the amount tabulated. Other fractiles are defined similarly. Fractiles are additive under the assumption of perfect positive correlation. Largest 

expected oil field size is in MMBO; largest expected gas field is in BCFG. Gray shading indicates not applicable].

For Additional Information

Assessment results are available at the USGS Central Energy Resources Science Center Web site: http://energy.usgs.gov/OilGas.aspx

or contact Craig J. Wandrey, assessing geologist (cwandrey@usgs.gov).

Taranaki Basin Assessment Team

Craig J. Wandrey, Christopher J. Schenk, Timothy R. Klett, Michael E. Brownfield, Ronald R. Charpentier, Troy A. Cook, 

Richard M. Pollastro, and Marilyn E. Tennyson.