From play to production: the Cooper unconventional story—20 years in the making

Abstract

The Cooper Basin is Australia’s leading onshore producing hydrocarbon province having produced more than 6 Tcf of natural gas since 1969. The basin is undergoing renewal 45 years later, driven by the emerging growth of east coast LNG export-driven demand. Following North America’s shale gas revolution, the Cooper Basin’s unconventional potential is now widely appreciated and it is believed to hold more than 100 Tcf of recoverable gas.

This resource potential is held in four stacked target unconventional lithotypes, each having demonstrated gas flows:

1. tight sands—heterogeneous stacked fluvial sands;

2. deep coal—porous dry coals, oversaturated with gas;

3. shales—thick, regionally extensive lacustrine shales; and,

4. hybrid shales—mixed lithotype containing interbedded tight sandstones, shales and coals.

Industry activity initially focused on the Nappamerri Trough, where more than 25 contemporary exploration wells have been drilled, proving up an extensive basin-centred gas play with >1,000 m of continuous overpressured gas saturated section outside of structural closure.

Santos has had a team focused on unconventional resources for nearly 20 years and successful results have been quickly tied into the producing infrastructure. This has been demonstrated with the Moomba–191 REM shale success, Moomba–194 and the recent Moomba–193H connection, one of the basin’s first fracture-stimulated horizontal wells.

Prospective geology, existing infrastructure and market access make the Cooper Basin well positioned for unconventional success. Each resource play is unique and commercial success requires considered adaptation of established technologies and workflows, based on a understanding of local geological and reservoir conditions. Commercialisation activity now seeks to define play fairways, characterise and prioritise reservoir targets and determine appropriate drilling and completion approaches.