The other Erregulla discovery, Wagina Sandstone, north Perth Basin

Abstract

Although the major focus of exploration within the onshore north Perth Basin and the greater Erregulla area has been the prolific high gas-rate Kingia discoveries, there are additional discoveries being made in sandstones within basal parts of the upper Permian Wagina Sandstone. During the drilling of the most recent of these discoveries at South Erregulla-1, a high-pressure porous interval was encountered within the lower part of the Wagina Sandstone at a depth of 3903 m. The Wagina Sandstone has been enigmatic in the deeper Dandaragan Trough. To date, 10 wells in the Dandaragan Trough have penetrated the entire upper Permian sequence, and all wells show some gas charge. However, nine of the 10 wells contain only minor amounts of mostly low-quality reservoir development. Only the South Erregulla-1 well contains conventional porosity as well as significant amounts of tight gas pay. The mechanism for preserving porosity in the basal Wagina sandstone is different to the early Permian Kingia Sandstone but provides an important and additional gas reservoir in the deepest Wagina penetration in the Perth Basin.