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.
Production Performance
Production began on 30 July 2007. Total production in FY08 (year ended 30 June 2008) was 14.2 million barrels. NZOG's share of production was approximately 1.78 million barrels
Oil Production since 1 July 2008:
1 July-04 September: Approx 2.4 million barrels. NZOG's share of production approx 300,000 barrels.
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$34m. The FPSO is the main operating cost.
In May 2008 an agreement was signed extending the charter of the Umuroa, through to the end of 2022.
Reserves
The proven and probable (2P) reserves for the Tui Area Oil Fields have been increased several times:
July 2007 27.9 mmbbls (Pre-production)
27 August 2007 32.0 mmbbls (Preliminary post-drilling review)
22 November 2007 41.7 mmbbls (Detailed post-drilling reassessment)
21 May 2008 47 mmbbls (Extension of FPSO charter)
20 June 2008 50.1 mmbbls (Field reassessment)
Production
Production from Tui has been higher than originally expected.
Associated water is being produced but at a lower rate than that predicted by the original field simulation models, allowing a high oil production rate to continue for longer.
The facilities have also performed extremely well. Total outages in the period up to 30 June 2008 were just 17 hours.
Production for the period ended 30 June 2008 was 14.23 mmbbls, against a pre-production estimate of around 9 mmbbls.
Expected production for the FY09 has been increased from 6 to 9 mmbbls.
Revenue
Tui oil is a light, sweet crude that is generally sold, with freight and quality differentials, against the regional Tapis benchmark crude. It is typically sold into refineries on the east coast of Australia or in south-east Asia.
Tapis Benchmark Crude - the weekly average Tapis price per barrel
|
Average Tapis Price |
NZ$ Equivalent |
|
|
29/08/08 |
US$123.48 |
NZ$176.27 |
|
22/08/08 |
US$121.18 |
NZ$170.99 |
|
15/08/08 |
US$123.38 |
NZ$174.54 |
|
08/08/08 |
US$129.89 |
NZ$184.24 |
|
01/08/08 |
US$135.03 |
NZ$183.71 |
|
25/07/08 |
US$139.87 |
NZ$186.49 |
|
18/07/08 |
US$151.97 |
NZ$198.39 |
|
11/07/08 |
US$148.64 |
NZ$195.83 |
|
04/07/08 |
US$148.60 |
NZ$195.53 |
The chart below shows the weekly average Tapis prices (in US dollars) so far in 2008, along with a conversion into NZ dollars.
Tapis Benchmark Prices 2008 [15kB]
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 just under US$100 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]
