The Talgeberry Birkhead reservoir? a seismic stratigraphic study

Abstract

Recent oil discoveries in the Jurassic-Cretaceous Eromanga Basin of south-west Queensland have been in a variety of zones and many are believed to be controlled mainly by stratigraphic variations. Talgeberry-1 was completed as a dual zone oil producer from the Cretaceous Wyandra Sandstone and mid-Jurassic Birkhead Formation. An appraisal well, Talgeberry-2, drilled at a structurally higher location, did not intersect either of these reservoirs but was completed as a producer from the Early Cretaceous Murta Member. This paper presents a model for the Birkhead reservoir, which has been the most prolific producer to date. At Talgeberry-1 the Birkhead reservoir is interpreted as a fining upwards channel fill sand overlain by a coarsening upward distributary mouth bar sand. The channel fill, with good reservoir parameters, is believed to be the main producing sand. Log analysis and core data support this interpretation. The 10 m sand has a recognisable seismic signature which has been confirmed by modelling. Mapping of this signature has identified a channel approximately 600 m wide meandering from east to west. Structural mapping shows an updip location but it would have poorly developed reservoir sand and should be avoided. Further drilling for development or pressure maintenance should be within the mapped channel.