Southern Amadeus Joint Venture

Tenement Information

The combined area is operated by Santos under a three stage farmout agreement with Central, with the exception of the EP 82DSA area which is operated by Central as part of arrangements in the purchase of Central’s interest in the Mereenie Oil and Gas Field.

Tenement Approx
Area
(km²)
Location Operator CTP Consolidation Entity Other JV Participants
Registered
Interest
(%)
Beneficial
Interest
(%)
Participant
Name
Beneficial
Interest
(%)
EP 82 * 9,923* Amadeus Basin NT Santos 60 60 Santos 40
EP 105 9,750 Amadeus/Pedirka Basin NT Santos 60 60 Santos 40
EP 106 ** 4,097 Amadeus Basin NT Santos 60 60 Santos 40
EP(A)111 9,065 Amadeus Bast NT Santos 100 50 Santos 50
EP 112  14,058  Amadeus Basin NT Santos 30 30 Santos 70
EP(A)124 *** 14,982 Amadeus Basin NT Santos 100 50 Santos 50
EP 125 12,761 Amadeus Basin NT Santos 30 30 Santos 70

* Excludes EP 82DSA (1,489 km²), excised from the Joint Venture with Santos as part of arrangements in the purchase of Central’s interest in the Mereenie Oil and Gas Field.

** Santos (as Operator) has continued the process of an application with the NT Department of Primary Industry and Resources for consent to surrender Exploration Permit 106.

*** Placed in moratorium for a period of 5 years, ending 6 December 2022.

Joint Venture

In October 2012, Central and Santos entered into a three-stage farm-in agreement.

Stage one was comprised of 1,586 km of 2D seismic in the Southern Amadeus area, 386 km 2D seismic in EP 115NMB, and drilling of Mt Kitty 1. These activities concluded in July 2014 with Santos earning 25% in EP82, EP105, EP112 and 70% in EP125.

Stage two comprised a further 1,337 km of 2D seismic. These activities concluded in October 2018 with Santos earning an additional 15% (to 40%) in EP82, EP105, EP112 and retained 70% in EP125.

Stage three comprised the drilling of Dukas 1 in EP112 with Santos earning an additional 30% (to 70%) in EP112 and retaining 40% in EP82 and EP105 and 70% in EP125.

Description and Geology

The Southern Amadeus Basin is a large and underexplored region characterised by northwest trending structures in the northern area, and a central area dominated by an east-west central structural ridge. The southern area has a variety of structural styles including basement involved structural highs, compressional folds and salt-cored thrusted anticlines. The proven Larapintine petroleum system in the Northern Amadeus is not present southwards, however, source rocks are also recorded deeper in the stratigraphic succession including in the Cambrian Tempe Formation and Chandler Salt.  The Neoproterozoic Pertatataka, Aralka, Finke Beds and Bitter Springs formations also show oil and gas source characteristics, in particular in the basal Gillen Member which provides the source for the Heavitree/basement play.

EP 82

Gas was discovered at Magee‑1 in 1992 where a test at a depth of 2,340 m flowed gas at a stabilised rate of 63 Mscfd, comprising natural gas, helium and nitrogen from a 6m zone of Heavitree Formation. Seismic data indicates a possible up dip location (Mahler) which requires additional seismic acquisition to confirm closure. Other Heavitree/fractured basement leads within the block (Jackalope and Wolpertinger) are based on potential field data and are targets for natural gas and helium, however, additional seismic acquisition will be needed to delineate the leads.

EP 105

This permit is immediately east of and geologically similar to EP 82.  Several leads have been identified from potential field data, the extensive 2013 regional seismic program, and field (outcrop) mapping. Regional seismic was acquired in 2013/14 and interpretation has identified the Mahler lead in adjacent EP 82 may extend into this permit. Other Heavitree/fractured basement leads within the block (Wolpertinger, Kraken, Thunderbird) are based on potential field data and are targets for natural gas and helium, however, additional seismic/fieldwork will be needed to delineate the leads.

EP 112

This permit contains a variety of structural styles, and several leads have been identified from potential field data and the extensive 2013 regional seismic program. Seismic acquired in 2013/14 and 2016/2018 identified the giant Dukas prospect at basement level. The Dukas-1 well was spudded 16 April 2019 targeting natural gas and helium from the Heavitree Formation, which flowed at sub-commercial rates from Magee 1. Drilling was suspended due to extremely high pressures before penetration of the Heavitree Formation or basement.  Drilling mud samples indicate the presence of hydrocarbons and helium and further analysis will be completed on well logs and gas samples. Central and Santos are planning a return to the well in 2021.This permit contains a variety of structural styles, and additional Heavitree Formation/fractured basement leads (Sculthorpe, Beethoven, Grainger, Percy, Mozart) have been identified from potential field data as well as the 2013/14 and 2016/2018 seismic programs.

EP 125

In 2014, the joint venture operated by Santos drilled the exploration well Mt Kitty 1 to test a large basement structure with closure up to approximately 200 km². The target Heavitree Formation reservoir was absent, but hydrocarbon and helium gas flows were recorded from fractured igneous basement, opening a new play type. This permit contains a variety of structural styles, and additional opportunities have been identified from potential field data and the extensive 2013 and 2016/2018 seismic data.

Exploration

In 2018, Santos elected to proceed to the third stage of the Farm-in agreement in EP112 by drilling the giant Dukas prospect. Drilling was suspended due to extremely high pressures before penetration of the Heavitree Formation or basement.  Central and Santos are planning a return to the well in 2021. The Southern Amadeus region contains a variety of structural styles, and additional Heavitree Formation/Fractured basement leads have been identified from potential field data as well as the 2013/14 and 2016/2018 seismic programs.

Opportunities

The size of the acreage and leads identified to date has encouraged the joint venture to acquire more seismic to identify prospects worthy of drilling. The percentage of helium recovered in known discoveries is in the range 4% to 9%, which is very high compared with worldwide analogues, and may represent a standalone commercial opportunity.