Santos Limited has successfully completed the Moomba South Patchawarra Formation phase 1 appraisal program in the Cooper Basin.
The Moomba South appraisal program is the first of several large-scale project appraisal phases in the Cooper Basin focused on contingent resource maturation.
In the past, the Patchawarra reservoir system on the deeper flanks of the Moomba South field has been assessed to contain significant gas potential in thick, well-developed, gas-charged tight sandstone reservoirs.
Santos’ current appraisal program targeted the maturation of a ‘significant’ 2C contingent gas resource within the Lower and Middle Patchawarra Formation.
These reservoir targets are proven productive intervals in the adjacent Big Lake and Moomba North fields.
Eight appraisal wells were drilled to total depths ranging from 3,034 to 3,303 metres and all intersected gas pay in the target Patchawarra Formation.
Gas pay in the wells ranged from 16 to 64 metres, which was in line with assumptions underpinning pre-drill contingent resource estimates.
Santos has stated that preliminary gas sample analysis indicates a higher natural gas liquids content and lower CO2 content compared to the adjacent and overlying Moomba field production areas. Further analysis is currently underway to confirm the gas composition and associated gas liquids volumes.
Seven of the appraisal wells have now been tested and brought online.
A peak stabilised single-well gas flow of 8.7 million standard cubic feet per day has been established.
One well was plugged and abandoned. In addition to the Patchawarra, the Company has stated that ‘significant’ upside in the Toolachee, Daralingie and Epsilon reservoir complexes has also been demonstrated, with several wells encountering near-virgin pressures and better than expected porosity and permeability.
Two emerging exploration opportunities were also targeted in the appraisal program: the Granite Wash play and the Fractured Granite play.
The Granite Wash is considered to be a proven producing horizon on the flanks of the Moomba North field.
The majority of the Moomba South appraisal wells penetrated this interval improving the overall understanding of this play.
Several of the appraisal wells have been tested and flowed stabilised gas rates from intervals of elevated gas shows through the Granite Wash.
Stimulation and testing of the Fractured Granite in one of the eight wells were also said to have demonstrated stable gas flows to surface.
The results of the appraisal programme are set to inform field development planning for the Moomba South project.
Moving forward, planning is under way to undertake further drilling on Moomba South towards the end of 2019.
This further drilling may include horizontal wells to further appraise the field.
Reserve and resource estimates for Moomba South are still to come.