“The Darwin formation was perforated and treated with two acid-wash procedures, which are often required to produce from fractured carbonate reservoirs,” MEO said.
“Despite this, and the evidence from electric logs of the presence of some significant fractures in the perforated section, the well failed to flow to the surface.”
But MEO said the joint venture, comprising itself (90%) and partner Petrofac (10%), remained optimistic that a significant hydrocarbon resource had been encountered in the Heron North Plover formation.
“The Heron-2 well provided sufficient modern log data to indicate that a good quality conventional sandstone reservoir and hydrocarbon resource is present, warranting further drilling and production testing,” MEO said.
“While it has been confirmed that the Plover sands did not contribute to the recorded flow due to blockages in the well immediately above the formation, the Elang sands did flow gas to surface at a maximum rate exceeding six million cubic feet per day.
“This hydrocarbon flow to surface supports an application for a retention licence application over the Heron North structure to secure the resource until further appraisal can be completed. An application is under consideration by the joint venture partners.”
However, the Epenarra Darwin formation was the main target, and having a fractured section of this reservoir failing to flow gas to surface greatly reduces the odds that Heron could support MEO’s proposed LNG project.
MEO said several geoscientific studies based on the Heron-2 data were needed before the partners could start detailed planning of future drilling to test Heron North.
The authorities have approved three sites for a second well – Heron-3B which targets the Darwin formation significantly down-dip from Heron- 2; Heron-3C which targets the Heron South structure expected to contain similar quality Plover reservoirs as Heron-2; and the wildcat Blackwood-1, which also has Plover reservoirs as its target.
“Given the positive indications to date, the joint venture is currently considering the suspension of Heron-2 to allow re-entry at a later date to re-drill the Plover formation in Heron North,” the company said.
