Cooper Energy announced on Friday that it has found new gas in the Annie-1 exploration well in the Otway Basin offshore Victoria, marking the first new offshore discovery in the basin in 11 years.
Annie-1, located in VIC/P44 approximately 9 kilometers offshore Victoria in a water depth of 58 meters, reached total depth (TD) of 2,442 meters measured depth rotary table (MDRT) on Wednesday.
Cooper Energy is operator and holds 50% interest in VIC/P44. Mitsui E & P Australia holds the remaining 50% interest.
Cooper Energy Managing Director David Maxwell described the Annie gas discovery as a solid and promising result from the first well in the program.
“Annie-1 is the first offshore gas exploration well Cooper Energy has drilled in Australia and the first of an $80 million drill campaign by the joint venture this year to find new gas supply for south-east Australia.
“We are very pleased with the success at Annie. It is very encouraging for future exploration in the offshore Otway Basin and for our strategy to build gas production around the hub of the existing Minerva Gas Plant.
“Preliminary analysis of the geological data from Annie-1 is consistent with the mid-range of our pre-drill estimates. In the coming months, we will complete the subsurface assessments and analysis of data to refine our estimates of field size and to inform decisions regarding field development,” Maxwell said.
Within the Annie-1 borehole, the Waarre C and Waarre A Formation sandstones productive in the Otway Basin were penetrated. The Waarre C primary target was encountered at 2,241 meters MDRT, comprising a gross gas column of 70 meters with gas-on-rock at its base. The net pay thickness is 62 meters, Cooper Energy said.
The deeper Waarre A sandstone was encountered at 2,341 meters MDRT and was water wet. The analysis was carried out using logging while drilling (LWD) data.
Wireline logging operations to collect pressure and sample data required to inform resource volume estimates and to determine gas composition have been completed. Data collected in Annie-1 is consistent with adjacent analogue producing fields. Laboratory analysis to confirm gas composition is to be conducted.
The field is located between the producing Henry (15 kilometers west) and depleted Minerva (11 kilometers east) gas fields.
Cooper Energy, which together with Mitsui E & P Australia currently produces gas from the nearby Casino, Henry and Netherby fields, said the presence of subsea infrastructure and future access to the existing Minerva Gas Plant enables the development economics for field discoveries in the region.
The timing of any development will depend on rig scheduling for the drilling of a development well. With this proviso, a favorable decision on field development could result in the commencement of production from the Annie gas field in the latter half of calendar 2021, Cooper Energy said.
The Diamond Offshore Ocean Monarch drilling rig is about to commence preparations to plug and abandon Annie-1, consistent with the work program previously announced. Following this, the rig is scheduled to move to drill the second well in the two well program, Elanora-1 in VIC/L24, 23 km southwest of Annie-1.