Publications

A diminishing prospect-inventory, based on traditional structural targets, has placed increasing emphasis upon finding commercially-viable stratigraphic traps. This is especially true in the Barrow-Dampier Rift where recent drilling has identified at least twelve depositional sequences within the Upper Jurassic to Lower Cretaceous succession. These sequences document a far more complex Late Jurassic to Early Cretaceous sedimentary history than previously recognized ding traditional lithostratigraphic mapping techniques. Use of a chronostratigraphic framework to develop a Late Jurassic and Early Cretaceous systems tract model reveals that several repetitive facies suites may be penetrated by the drill, depending on geographic location and frequency of lowstand events. These models have profound implications for prediction of Upper Jurassic to Lower Cretaceous submarine fan systems, their potential reservoir distribution, and sealing capaciw for hydrocarbon entrapment.Sequence boundary development is closely related to major tectonically-induced changes in basin architecture associated with progressive continental breakup of Eastern Gondwana Deposition of Callovian to Oxfordian sequences, for example. occurred nhilst the BarroIv and Dampier sub-basins JT ere tu o distinct structural entities separated by a complex intra-basinal arch. In this context, early Callovian to Oxfordian basin-floor sand cycles were locally confined to the rift margins and peri-rift terraces, forming mixed channel lobe and fan mound forms. Kimmeridgian to Tithonian depositional sequences, however, are more widespread with sediment transport of up to 40 km. These followed marked submergence of the intra-basinal arch, allowing widening of the sub-basins into one tectonic entity, giving rise to deposition of thick, detached, non-channelised lobes.During the following Early Cretaceous succession, the southern Barrow Rift was completely inundated by the Barrow fluvio-deltaic system, deposited orthogonally to the preexisting Jurassic rift trend. Continuous delta-switching and episodic disruptions to sediment supply were caused by syndepositional tectonism and/or eustatic sea level fluctuations producing widespread lowstand deposits. Major hydrocarbon reserves are trapped in both fluvio-deltaic and submarine fan reservoirs of the Barrow Delta system.In the Dampier sub-basin, where a more complete and thichker Kimmeridgian to Tithonian interval exists, identified sequences demonstrate an apparent synchroneity with the world-wide global eustasy curve. especially with third-order cyclcs This may be a function of thc effect of the breakup of Eastern Gondwana on accommodation space and eustasy on a global scale.