ConocoPhillips’ Charlemont gas discovery could be one of largest in Australia’s offshore Otway Basin

ConocoPhillips’ Charlemont-1 exploration well offshore Victoria has proven more gas in deeper intervals.

The semisub Transocean Equinox started drilling operations on Dec. 10 last year, with a 7-inch liner installed on entry into the Waarre C reservoir at 2,552 m MD. According to partner 3D Energi, this followed higher-than-expected formation pressures related to substantial gas shows.

Drilling into the Waarre C resumed on Jan. 2 of this year, with elevated gas readings recorded across the reservoir sandstones. More gas readings then occurred throughout the deeper Waarre B sandstone intervals and through the primary Waarre A to 2,753 m MD.

At that point, the well reached a zone with higher-than-anticipated formation pressures, at the limit of operational tolerances. This led the partnership to halt operations prior to the planned total depth of 2,862 m.

They are now considering further wireline logging operations to determine the nature and extent of any hydrocarbons in the Waarre B and Waarre A, 3D Energi said, and any potential connectivity with the Waarre C

“The identification of probable hydrocarbons in the Waarre C is significant, as hydrocarbons were not anticipated in this zone prior to drilling," 3D Energi Executive Chairman Noel Newell said. “The presence of gas across stacked Waarre sandstone reservoirs de-risks the updip prospects with DHIs in the Charlemont Trend, culminating with the La Bella discovery. If successfully appraised, this cluster could be among the largest gas pools in the Otway Basin."

ConocoPhillips Australia operates with a 51% interest, in partnership with Korea National Oil Co. (29%) and 3D Energi (20%).