INFLUENCE OF DEPOSITIONAL ENVIRONMENT ON DIAGENESIS AND RESERVOIR QUALITY - TIRRAWARRA SANDSTONE RESERVOIR, SOUTHERN COOPER BASIN, AUSTRALIA

Mechanical compaction and quartz cementation are the most important di agenetic controls on the reservoir quality of the Late Carboniferous - Early Permian fluvio-deltaic Tirrawarra Sandstone in the Cooper Basin of South Australia. The magnitude of these two diagenetic events is c ontrolled by the miner alogical composition of the sandstones. Assumin g that the Tirrawarra Sandstones have a common provenance, the nature of the environments in which these sediments were deposited is the pri ncipal factor controlling the composition of the framework grains in t he unit. Thus, the percentage of rock fragments decreases, and the rel ative quartz content increases, from the medial part of a braid-delta to point-bar and aeolian environments. The content of ductile rock fra gments controls the degree of compaction and the development of quartz overgrowths.