Predicting sequence stratigraphic architecture and its implication for hydrocarbon reservoir potential of the uppermost Silurian through Lower Devonian Winduck Interval, central Darling Basin of western New South Wales, SE Australia

Abstract

This paper provides the results of lithostratigraphy and depositional environment of the uppermost Silurian through Lower Devonian Winduck Interval section from three areas widely distributed in the central Bancannia Trough from Bancannia South 1 well, the southern Pondie Range Sub-basin from Pondie Range 1 well and the northwestern part of the Blantyre Sub-basin from two wells, the Booligal Creek 1 and 2. These wells were studied using wireline log, core and cutting data to predict sequence stratigraphic architecture and its implication for hydrocarbon sandstone reservoir potential. This study necessitated the use of detailed facies prediction relationships and geometry of lithostratigraphic concepts for the purpose of establishing a sequence stratigraphic architecture framework of the studied areas. Two units were established, lower and upper Winduck Interval, within the Winduck Interval identified by lithological data examination and wireline log characteristics of the sediments from the four wells in the study area. Results of the lithology type analysis showed that the Winduck Interval is interbedded richly in sandstone and siltstone complex deposits. This paper presents a clear picture of the sequence stratigraphic model, as well as that of the three third-order depositional sequences (DS1, DS2 and DS3, respectively) that are identified from changes in systems tracts patterns (composed of lowstand, transgressive and highstand), vertical and lateral facies sequence thickness changes and the lithostratigraphic units distribution in the Winduck Interval section. Potential reservoir prospectivity targets are identified in lowstand system tracts and highstand system tracts deposits consisting of sandstone facies and thin silts, while the transgressive system tracts deposits consist of shales and some interbedded shaly siltstones, many having excellent potential source and seal properties. The contribution of sequence stratigraphy as an approach to understanding lithostratigraphy of the Winduck Interval has important significance in regard to future hydrocarbon reservoirs exploration across the central Darling Basin.