Petroleum reserves data shows decline in gas reserves

Published: 13 July 2023

The Ministry of Business, Innovation and Employment (MBIE) has today released annual data detailing the amount of oil and gas expected to be available in existing petroleum fields.

This year’s data, supplied to MBIE by both onshore and offshore permit holders, shows a 17% decrease in Proven plus Probable (2P) reserves. 1635 Petajoules (PJ) of 2P Gas reserves have been reported as at 1 January 2023, down from 1967 PJ a year earlier.

The most significant decreases in 2P reserves came from the Mangahewa and Maui fields which saw a decrease in 48% and 34% respectively.

Mike Hayward, Manager Markets in MBIE’s Digital, Data & Insights group, says “MBIE releases this data to give visibility to industry and consumers about the expected lifespan of oil and gas in New Zealand based on current permits.

“Oil and gas are a finite resource and gas continues to play an important role in the energy system. We hope that by sharing this information, we can support informed gas supply and investment decisions to be made across the sector.”

Estimated gas reserves have now dropped below ten years of remaining use for the first time, based on an average gas use of 200PJs over the last 10 years. However current gas use and supply are below this level.

In 2022, Aotearoa New Zealand used 145PJs of gas, compared to 155PJs for 2021 and 183PJs for 2020. This decline was driven by a reduction in industrial use due to the mothballing of Methanex’s Waitara Valley facility, closure of the Marsden Point oil refinery, and a decline in gas use for electricity generation. 2022 was the wettest and warmest winter on record, which led to more electricity being supplied from renewable hydro generation.

In previous years gas use has been balanced by increases in 2P reserves. However, in 2022 there was an overall net decrease of 332PJ in gas reserves from a combination of both gas use and revisions of remaining 2P gas reserves.

The reserves release includes updated estimates of future gas production. This shows production is expected to drop below 2022 gas use of 145PJs in 2027 without continued conversion of 2C contingent reserves into 2P reserves.

There was also a 41% decrease in 2C Contingent reserves in 2022. 2C Contingent reserves represent potential resources that may be able to be converted into 2P reserves in the future. This decrease was primarily due to technical revisions by operators due to performance data.

This data includes:

  • oil and gas production profiles
  • remaining reserves
  • contingent resources.

Petroleum reserves data

The Energy in New Zealand 2023 publication, due to be published in August, will include the full range of statistics for the 2022 year.

Note: Petroleum reserves are summary statistics based on reporting from permit and licence holders. These holders are required to report oil, gas and liquefied petroleum gas (LPG) reserves information every year under the Crown Minerals Act 1991.

MBIE media contact


Notes about the Gas Transition Plan

  • MBIE is currently developing a Gas Transition Plan to support the phase out of fossil gas in line with New Zealand’s emissions reduction targets.
  • MBIE expects to open consultation on the pace and direction of the gas transition shortly.