Amadeus Basin

Mosman owns Adagio Resources Limited which in turn owns Trident Energy Pty Ltd and OilCo Pty Ltd.  Trident owns EP145 and OilCo owns EP(A)155.

The Amadeus Basin is considered one of the most prospective onshore areas in the Northern Territory of Australia for both conventional and unconventional oil and gas, and hosts the producing Mereenie, Palm Valley and Surprise fields.


The permit contains a significant anticline (named West Walker), over 30km in length, which hosts Ordovician through to Neoproterozoic stratigraphy with prospective targets at multiple levels of over 30km in length. The significance of the geology is its proximity to the nearby Mereenie oil and gas field, which produce from the Ordovician Pacoota Sandstone unit.

Two wells have been drilled on the anticline, the first West Walker -1 tested the western end of the feature. The well was drilled on a sparse seismic rid in 1982 and flowed wet gas to surface at a ratqe of 3.5MMscf/d from the Pacoota Sandstone, the main producing reservoir in the Mereenie and Palm Valley Fields. A follow up well drilled, Tent Hill-1 (1984), was drilled to the southe4ast on the same anticline, oil was obsereved seeping from cores but the well was not tested. Reprocessing of the vintage seismic data shows that both wells were drilled off structure, West Walker-1 drilled downdip of the main closure and Tent Hill-1 did not penetrate the target sandstone within closure.

As part of Mosman's initial technical evaluation SRK Consulting (Australia) were contracted to produce an independent report ("SRK Report, 2015") into the prospective resources contained in permit EP145. The report highlights the potential for both conventional oil and gas resources in proven reservoirs within the West Walker Anticline and unconventional gas resources in the Horn Valley Siltstone. More recent technical work by Mosman and Geognostics, Australia has highlighted the potential for helium and hydrogen in addition to the hydrocarbon resources documented by SRK. The exploration program has been revised to focus on the potential of EP145 to contain resources of hydrocarbons, helium and hydrogen and multiple levels within the stratigraphy as demonstrated elsewhere in the basin.

Latest Article: Hidden Hydrogen : Does Earth hold vast stores of a renewable, carbon-free fuel? ( - 17 February 2023 - Vol 379 Issue 6633)

Prospective Resources (Bcf)

Low Estimate

Best Estimate

High Estimate

Total Gas of 



2, 290









Source: Mosman Oil and Gas Ltd, October 2022

In June 2023 approval was granted by the Northern Territory Government to extend the current permit year (activity period) by 12 months to provide necessary time for approvals to be obtained for the seismic work program.  This means that Mosman currently has until 21 August 2024 to complete the Year 3 Work Program that includes acquisition of 2D seismic, processing and interpretation of the seismic, identifying well locations and detailed planning.

The Year 4 Work Program must now be completed by 21 August 2025 including drilling an exploration well and assessing the results thereof.

The Year 5 Work Program must be completed by 21 August 2026 and includes a second exploration well, analysis and interpretation, reservoir studies, and preparing to apply for either a Retention Lease, Production Licence, Permit Renewal, or relinquishment.

Once the heritage and environmental surveys are completed, the next step will be to progress the technical the technical work to further define the prospectivity of the permit.  This will include the acquistion and interpretation of 2D seismic, prior to identifying a drilling location and drilling an exploration well."

All seismic and drilling activities are subject to obtaining the necessary planning approvals from the NT Department of Industry and Resources, which are currently being coordinated by the project manager (ResourceGeo). 

In 2021 the Airborne Gravity and Gradiometry data acquisition for permit EP-145 was commpleted. The survey is a significant step in the exploration program as it is the first time data will be acquired for the whole permit.  The survey used high resolution Falcon Airborne Gravity Gradiometry System which has the abililty to image salt and subsalt geometry across a range of depths.

Geognostics Australia were engaged to interpret the data which is being integrated into the regional basin model.  

Planning for the acquisition of seismic is ongoing.

The Aboriginal Areas Protection Authority (AAPA) sacred site clearance certificate has been received.  The Central Land Council (CLC) has recently issued a Sacred Site Clearance Certificate for EP145.

The next step for Mosman is to secure the Environmental Survey in conjunction with the CLC. 

Once completed, the next step will be to progress the technical work to further define the prospectivity of the permit. This will include the acquisition and interpretation of 2D seismic will comprise the next significant exploration activity in the current permit year (expiring August 2023), prior to identifying a drilling location and drilling an exploration well.

All seismic and drilling activities are subject to obtaining the necessary planning approvals from the NT Department of Industry and Resources, which are currently being coordinated by the project manager (ResourceGeo). In anticipation of any further delays to project approval Mosman has secured a further extension and suspension to the current permit year.

EP(A)155 Mount Winter

Located in the Northern Amadeus Basin between the producing Surprise Oil Field and Mereenie Oil and Gas Field has significant prospectivity for helium, natural hydrogen and hydrocarbons.

EP(A)155 lies within the highly prospective Horn Valley Siltstone fairway with proven hydrocarbon potential as demonstrated by historical wells, Mt Winter-1 & 1A. Exploration data comprises a sparse 2D seismic grid and 2 wells.

Mt Winter-1 was drilled to a depth of 2650m reaching TD in the Proterozoic Gillen Fm, above the helium and hydrogen prospective targets. Hydrocarbons were encountered in 2 intervals, the Ordovician Stairway Sandstone (reservoir at Surprise Field) and Proterozoic Jonny’s Creek Beds (reservoir at Ooaramina discovery, northeastern Amadeus Basin). The well was drilled off structure due to the limited seismic data available, and re-interpretation of the available data suggests valid targets at multiple depths down to and including basement.

EP(A)155 is an exploration permit application, subject to successful land access negotiation with Traditional Owners prior to grant of the permit.

Mosman entered into a farmout agreement with Westmarket Oil and Gas Pty Ltd, a wholly owned subsidiary of Georgina in 2020.  Georgina are responsible for the Native Title Negotiations as required for grant of the permit.  Georgina  will also undertake the initial technical work program which includes acquisition of seismic data to earn a 75% working interest and operatorship of the permit. On drilling an exploration well Georgina has the option to earn a further 15% working interest by electing to carry Mosman through the cost of the well.