--> Abstract: High Resolution Reservoir Model Development: A Case Study from the Barrow Delta, Exmouth Sub-Basin, Western Australia, by Stewart Easton and Carl Jonathan Stark; #90039 (2005)

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High Resolution Reservoir Model Development: A Case Study from the Barrow Delta, Exmouth Sub-Basin, Western Australia

Stewart Easton1 and Carl Jonathan Stark2
1 BHP Billiton Petroleum, Perth, Australia
2 Firmground Pty Ltd, Perth, Australia

The Lower Cretaceous Pyrenees Member of the Exmouth sub-basin, Western Australia, forms the basis for a multi-field offshore oil development. The complexity of the Pyrenees Member with regard to sandbody distribution and connectivity, resulted in significant uncertainties with regard to hydrocarbon volumes in place, recoverable reserves, associated aquifer volume and water drive support mechanisms.

Seismic mapping, biostratigraphy, chemostratigraphy and sedimentology (including core and FMI), were used to construct a high-resolution sequence stratigraphic framework. Two 3rd order sequences are recognised. The lower sequence initially comprises a series of prograding parasequences, dominated by wave and tide-influenced shoreface and shelf deposits. The transition to an aggradational stacking pattern marks the deposition of interdigitating shoreface, tidal channel and tidal flat facies. The upper sequence is characterised by initial lowstand incision and deposition of coarse fluvial strata. These are overlain by a regionally correlatable flooding surface, marking a major landward shift in facies and deposition of bioturbated shoreface and tidal channel strata.

This sequence-stratigraphic framework enables the construction of a detailed multi-field 3D reservoir model, capturing the fine-scale reservoir geometry, yet suitable for development and production planning. Seven discrete modelling sub-zones were recognised within the fine-scale (50x50x1.5m) 3D geological model. These units were further populated by 18 lithofacies. Each field was then cropped out into smaller sub-models and exported for reservoir simulation without upscaling.

This approach to reservoir simulation modelling has addressed and significantly reduced the level of uncertainty, and enabled the creation of a multidisciplined environment for the ongoing multi-field development.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005