The Tui Area Oil Fields are located in the offshore Taranaki basin, New Zealand, approximately 50km off the coast in water depth of about 120m. Production began on 30 July 2007 - just 4½ years after discovery, and 20 months after the investment decision was taken. Tui was New Zealand's first stand-alone offshore oil development.
In July 2011, the Operator AWE announced a preliminary reserves review. Following further assessment, a new estimate of 41 mmbbls for Tui's gross initial developed 2P Reserves has been adopted.
As at 31 December 2011, Tui's remaining developed 2P Reserves were 8.8 mmbbls - NZOG's share 1.1 mmbbls.
Tui Movie
Click here to view a short film on the development of the Tui Oil Fields.
The Tui joint venture partners are:
New Zealand Oil & Gas Limited* 12.5%
Australian Worldwide Exploration (AWE)* 42.5%
Pan Pacific Petroleum* 10%
Mitsui E&P Australia Pty Limited 35%
*via subsidiaries
AWE is the Operator of the Tui Area Oil Fields, on behalf of the Joint Venture.
The Development
The Tui Area Oil Fields lie within PMP 38158. Three separate oil accumulations have been developed - Tui, Amokura and Pateke.
The development comprises four horizontally drilled and subsea completed wells, each tied back to a leased Floating Production Storage and Offtake (FPSO) vessel, the "Umuroa". The extended horizontal production sections in the oil reservoirs range from 819m to 1850m.
The Tui Area Oil Project was developed at a cost of US$274m, with NZOG's share amounting to US$34m. The FPSO is the main operating cost.
In May 2008 an agreement was signed extending the charter of the Umuroa through to 2015, with one year rights of renewal until 2022.
Production
January 2012: approximately 182,000 barrels of oil. NZOG's share 22,800 barrels.
1HFY2012 (July-Dec): approximately 1.2 million barrels of oil. NZOG's share 147,000 barrels.
Tui production began on 30 July 2007. Total oil production to 31 January 2012 is approximately 32.35 million barrels. NZOG's share of total production is approximately 4.05 million barrels.
FY2011: 2.81 mmbbls. NZOG's share 350,000 barrels.
FY2010: 4.83 mmbbls. NZOG's share 604,000 barrels.
FY2009: 9.12 mmbbls. NZOG's share 1.14 mmbbls.
FY2008: 14.23 mmbbls. NZOG's share 1.78 mmbbls.
Production from Tui has been higher than originally expected.
Associated water has been produced at a lower rate than that predicted by the original field simulation models, allowing a high oil production rate to continue for longer.
The facilities have also performed extremely well. Oil has been produced on every day apart from a scheduled six day maintenance shutdown in December 2008, a scheduled seven day facility upgrade and maintenance shutdown in November 2010, and a two day shutdown to allow repairs to a gas compressor unit in June 2010.
The Pateke well suffered a problem with its artifical lift system and was shut-in in late June 2010. A workover was completed ahead of the well resuming production in October 2010.
Historic production performance
Production for the period ended 30 June 2008 was 14.23 mmbbls, against a pre-production estimate of around 9 mmbbls.
Production for the year ended 30 June 2009 was 9.12 mmbbls, against an original forecast of 6 mmbbls and a revised forecast of 9 mmbbls.
Production for the year ended 30 June 2010 was approximately 4.83 mmbbls, against an original forecast of 5.1 mmbbls and a revised forecast of 4.8 mmbbls.
Production for the year ended 30 June 2011 was approximately 2.81 mmbbls, against an original forecast of 3.1 mmbbls and a revised forecast of 2.8 mmbbls.
Reserves
Evaluation of the initial proven and probable (2P) reserves for the Tui Area Oil Fields have changed a number of times as new information and analysis becomes available:
November 2005: 26.8 mmbbls (Project sanctioned)
July 2007: 27.9 mmbbls (Pre-production)
27 August 2007: 32.0 mmbbls (Preliminary post-drilling review)
22 November 2007: 41.7 mmbbls (Detailed post-drilling reassessment)
21 May 2008: 47 mmbbls (Extension of FPSO charter)
20 June 2008: 50.1 mmbbls (Field reassessment)
25 August 2009: 50.5 mmbbls (Reserves Review)
September 2011: 41 mmbbls (Reserves Review)
Revenue
Tui oil is a light, sweet crude that was initally sold, with freight and quality differentials, against the regional Tapis benchmark crude. From July 2010 it was sold at a premium above an average of APPI Tapis and Dated Brent. With declining use and industry confidence in APPI Tapis, in 2011 Tui sales were moved entirely to benchmarking, with a premium, to Dated Brent. Tui oil is typically sold into refineries on the east coast of Australia or in south-east Asia.
For the year ended 30 June 2011, NZOG's share of production was around 350,000 barrels. NZOG received NZ$41.14m in revenue, with an average sales price of approximately NZ$125 per barrel.
For the year ended 30 June 2010, NZOG's share of production was around 604,000 barrels. NZOG received NZ$67.9m in revenue, with an average sales price of approximately NZ$104 per barrel.
For the year ended 30 June 2009, NZOG's share of production was around 1.14 mmbbls. NZOG received NZ$138.7m in revenue, with an average sales price of approximately NZ$122 a barrel.
For the year ended 30 June 2008 (11 months of production) NZOG received NZ$222.8m in Tui revenue, from the sale of approximately 1.78 million barrels, at an average price of approximately NZ$125 a barrel.
NZOG achieved project ‘payback' - recovery of all exploration and development costs for the Tui Area Oil Project - in approximately four and a half months.
History
The Tui-1 oil discovery was a wildcat well drilled by NZOG and partners in February 2003 and the development decision was taken in November 2005. Read more »
History
The Tui-1 well drilled in February 2003 encountered a 10m oil column in excellent quality reservoir. A marine seismic survey was subsequently carried out over 250 sq km in April 2003 to delineate the Tui field accumulation and other nearby structures.
Based on the 3D seismic mapping, NZOG and partners drilled further exploration wells on nearby structures similar to the Tui field during 2004. The Amokura-1 well was drilled in April 2004, and encountered a 12m oil column. The Pateke-2 well was drilled in August 2004 and also encountered a 12m oil column.
A further marine seismic survey over approximately 150 sq km was carried out on behalf of the joint venture in April 2005.
In November 2005 the Tui joint venture partners made a unanimous decision to fast-track the development of the Tui Area Oil Fields.
Commercial Production began on 30 July 2007.
Technical Achievements
The Tui Area Oil Project achieved a number of firsts for an oil field development in New Zealand. Read more »
Technical Achievements
Technical highlights of the Tui Area Oil Project include:
Geosteerable drilling of the four horizontal oil production wells (a first for New Zealand);- The longest horizontally drilled wells in New Zealand;
- Subsea wellhead completions (the first of their kind in New Zealand);
- Modification of the FPSO to include an innovative swivel production turret, allowing the vessel to swivel for currents and weather whilst maintaining production output;
- Additional tie-back options to the FPSO - if other adjacent prospects are discoveries, this allows for rapid online production of additional reserves.
Geology
The reservoir is at a depth of around 3650m below the seabed. Read more »
Geology
The oil accumulations are in the Kapuni-F sandstone units, deposited during the Paleocene in the 'Kapuni' paleogeographic shoreface fairway. The reservoir is at a depth of around 3650m subsea.
Organic-rich shale sediments and coals of the Late Cretaceous and Paleocene are the likely sources of the oil, generated at deep depths within the Taranaki Basin 'kitchen' areas, such as the Kahurangi sub-basin to the west and northwest of the Tui area accumulations. The oil migrated vertically through faults and fractures and then laterally via carrier beds, finally accumulating in Paleocene sandstone reservoirs within structural trap closures.
The structural traps are low relief, dip-closed features. The reservoirs are clean, laterally extensive, high permeability marine sandstones, with the oil accumulations overlying strong aquifer drives.
Tui Oilfields Schematic [742kB]
FPSO Schematic [91kB]
