Hot water for Taranaki oil projects

TARANAKI’S waxy crudes present special challenges for oil project developers, delegates to this week’s New Zealand Oil and Gas Conference in New Plymouth were told.

OMV New Zealand asset manager Wolfgang Lebb said a lot of the $US457 million ($A565 million) offshore Taranaki Maari oil development would involve using hot water to prevent Maari crude from solidifying. OMV operates the Maari project.

He said water, heated to about 55C, would be used downhole in the planned five production wells. The storage tanks onboard the Raroa FPSO would also be heated.

In addition, umbilicals would contain a pour-point depressant (PPD) and flowlines would be heated with hot water from the usually unmanned platform.

Lebb said the Raroa would be slightly smaller than the Tui Area’s Umuroa FPSO, having a maximum processing capacity of about 40,000 barrels per day, compared to the Umuroa’s 50,000bpd.

There would also be water injection facilities, of up to 40,000 barrels of water per day, aboard the platform and three water injection wells to “sweep” the field of oil.

OMV expected the Maari drilling team to shift from Perth to New Plymouth late this month or early October. Field activities were due to start later in the year, he added.

The wellhead platform was due to arrive from Asia in the first quarter of 2008, while drilling was scheduled to start in the middle of that year.

Kupe operator Origin Energy and its partners will use the jack-up Ensco Rig 107, due to arrive in New Zealand waters next month, first for drilling the Kupe development wells, and at least the nearby Momoho-exploration well, before OMV takes the jack-up.

Austral Pacific Energy petroleum engineering manager Joe Johnston told delegates much of the $NZ30 million development of the small onshore Taranaki Cheal oil field also involved using hot water to counter the problems of waxy crudes.

The Cheal field – with its 2P (proved plus probable) reserves of 2.6 million barrels of oil and 1.8 billion cubic feet of gas – is producing about 850 barrels per day and is on target to ramp up to 1200-1500bpd next year.

Johnston said Cheal oil was found at temperatures of about 43-44C in the Miocene-aged Moki, Mount Messenger and Urenui reservoirs. However, this dropped as it came to surface, necessitating the use of a PPD to keep it at temperatures of at least 39C to stop it solidifying.

The Cheal A wellsite production facilities, which had hot water running through them, also fed that water to the B wellsite facilities. Storage tanks were also heated, as were the road tankers that trucked the crude to the Omata tank farm for export from Port Taranaki at New Plymouth.

Austral operates Cheal with a 69.5% interest and Canadian-listed junior TAG Oil holds 30.5%.

However, Origin Energy Kupe project director Peter Ashford told delegates that from data gained from drilling the first Kupe wells nearly 20 years ago, waxing did not appear to be a problem for condensate from that offshore Taranaki field.

“We know that Kupe condensate has a reputation of being waxy, but we think not. However, we are prepared.”

Anti-freeze could be added to the flowlines if necessary and storage tanks at the onshore production station could be heated to keep the condensate above 50C and so prevent any solidifying, Ashford added.

The Maari partners are operator Austrian major OMV (69%), Todd Energy (16%), Horizon Oil (10%) and Cue Energy Resources (5%).

The Kupe partners are operator Origin (50%), Genesis Energy (31%), New Zealand Oil & Gas (15%), and Mitsui E&P NZ (4%).

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