International consultants Gaffney, Cline & Associates, which undertook the analysis, also increased their low estimate from 193 to 254Bcf, and their high estimate from 435 to 619Bcf.

Since GCA’s previous resource estimate in April last year, Nexus has reprocessed the 3D seismic data over Longtom.

Nexus managing director Ian Tchacos said interpretation of this data indicated there was likely to be considerably more gas in the field.

“We are very excited by the increased resource estimates and eagerly look forward to the drilling of the Longtom-3 well, that if successful, will allow us to take this large resource base into development pursuant to our gas sales agreement with Santos,” he said.

The Longtom-3 appraisal well is now expected to spud in the second half of June – a month behind schedule due to the Basker/Manta development wells taking longer than expected, Nexus said.

Longtom-3 is being drilled by Nexus as a sole risk project. If successful, Nexus will have 100% interest in the Longtom field unless Apache exercises its buy back rights by paying Nexus six times the cost of its share of the well plus back costs associated with its share of the program.