Publication Name: Australasian Exploration Geoscience Conference 2019
Authors: Mark Bunch
Date Published: September 2019
Number of Pages: 7
Abstract:
Carbonate cemented zones were identified within the lower Paaratte Formation of the eastern Otway Basin, Victoria, in southeastern Australia. A wireline log model trained on these zones can predict carbonate cementation within Late Cretaceous to Paleocene reservoir sandstones of the Latrobe Group, Gippsland Basin, 100s of km to the east. Predictions are supported by published evidence and match cementation facies interpreted for other data acquired there. These sandstones are thought to have once been heavily cemented prior to development of secondary porosity that produced the world-class petroleum reservoirs we see today. Cemented zones that remain must act as obstructions to reservoir fluid migration. They may also react with the mild carbonic acid that would be introduced by CO2 storage (sequestration) operations of the future. Model predictions show that cemented zones are sparse, spatially sporadic and fall well below seismic survey resolution at modern-day reservoir depths. This study emphasises the challenge in mapping their distribution but provides predictions against which to measure future mapping attempts.