Biostratigraphic And Sequence Stratigraphic Correlation Of The Last Barrow Group Foreset, Barrow Sub-Basin.
Honours Degree, 1999
University of Adelaide
The John Brookes gas discovery is located in a Neocomian turbidite basin floor fan at the toe of the Barrow delta system on the North West Shelf, and has highlighted the importance of a sequence stratigraphic framework to predict other similar reservoirs in the Barrow Sub-basin.
The aim of this study was to develop a sequence stratigraphic framework and depositional model with a view to determining the timing and controls on reservoir development within the S. areolata biozone. This study involves analysis of eight wells in a depositional dip section utilising sequence stratigraphic concepts. A review of core descriptions and photography, existing sedimentological models and the integration of well log and palaeontology data was carried out to determine the different depositional environments within the Upper Barrow Group.
Cored intervals from the John Brookes #1,East Spar #1, #2, and #3 wells have been divided into nine different facies types. Depositional environments of facies involved sandy high-density turbidity deposits, lower to upper shoreface deposits, and tidal deposits.
Two complete sequences and two incomplete sequences were recognised within the S. areolata biozone, dominated by highstand and lowstand systems tracts. Various key surfaces were present within the study interval including three sequence boundaries and four maximum flooding surfaces.
A depositional model for the John Brookes reservoir succession is proposed with sandy turbidite channel-levee complexes being deposited in a Lowstand Systems Tract, at the toe of the Barrow delta system during several major cycles of relative sea level fall.