A technical and economic review was undertaken after the Crux-2 appraisal well failed to encounter the uppermost ‘A’ gas reservoir structure as intersected in the Crux-1 discovery well.

As a result, the Melbourne-based company said the best estimate contingent resource was now 55 million barrels of liquids, as opposed to the 71 MMboe it had previously predicted. 71MMboe is now the upside estimate.

The previous estimate was released during a heated takeover battle in which Nexus was trying evade the clutches of Anzon Australia. At the time, the boost to Crux's contingent reserves suggested that the Anzon offer was underpriced.

Nexus says this revised estimate would yield a pre-tax net present value of $710 million, at a discount rate of 10%.

The revised low estimate contingent resource for the field is 40MMbbl, with a value of $380 million. The high estimate contingent resource of 71MMbbl would yield $1.1 billion.

But the technical review of down-hole gas samples recovered from Crux-2 indicates the liquids content of gas in the Crux field is 30% higher than previously calculated after drilling Crux-1.

Nexus said two gas recycle cases have been considered and costed based on a recently completed front-end engineering and design work.

These are 600 million cubic feet per day recycled (for the low and best estimate contingent resource cases), and 900MMcfd recycled (for the high estimate contingent resource case).

Nexus said these cases yield liquids rates of 19,000 barrels per day and 29,000bpd, respectively.

The company said the resource estimates for the field exclude any resources from either the Plover sandstone encountered in Crux-2 or the potential extension of Crux into the recently awarded AC/P41 permit.

It said these results support Nexus’ appraisal strategy of drilling one additional well later this year.

The company plans to progress to a financial investment decision in early 2008, with first liquids production expected in early 2010.

It said the drilling of additional wells in the South East Crux extension and the Sextans field extension will also be drilled post-FID.

“These results illustrate the potential of the Crux liquids project,” managing director Ian Tchacos said.

“Nexus is confident that a substantial liquids resource exists at Crux and will continue to aggressively pursue this valuable project in order to bring it to development within 12 months.”