PESA WA May Evening talk: Rafael-1 – a tantalising gas-condensate discovery in the onshore Canning Basin

Kurt Chambers, Buru Energy

The Rafael 1 exploration well was drilled in the onshore Canning Basin by Buru Energy in late 2021 and made an exciting gas-condensate discovery in Devonian dolomites. The well tested a significant four-way structural closure mapped on a sparse regional 2D seismic grid, although the stratigraphic succession at the well location was difficult to predict due to the limited and distant well control.

There were several surprises and challenges that were compounded by the remote operational conditions of the onshore Canning Basin. The significant uplift and erosion observed at the Meda Unconformity in the Late Carboniferous in offset wells is much less pronounced at the Rafael 1 location with the preservation of a relatively complete Anderson to Laurel Formation sequence. Prior to drilling, the structure was thought to most likely be filled with oil primarily due to the Laurel Formation source rock being interpreted as absent in the flanking depocentres. Despite the Canning Basin having a substantial endowment of tight gas resources, it is generally accepted that hydrocarbon columns will be small due to its complex structural history. However, Rafael 1 encountered a significantly over-pressured 165m gross gas column, with gas on rock pointing to a potentially much larger column being present.

The Rafael 1 discovery has challenged a number of paradigms about the Canning Basin and supports the contention that significant volumes of gas in conventional reservoirs are yet to be discovered despite sporadic exploration over the past 100 years. The well also confirms that opportunity hides where high geological complexity and sparse datasets intersect.