Shallow Marine Analogues
Shallow and marginal marine reservoirs hold the vast majority of the remaining hydrocarbon reserves. Identification and prediction of heterogeneities in these reservoirs is therefore key to efficiently and economically producing these volumes. Wave-influenced shallow marine systems are generally regarded to form good quality, highly continuous reservoirs. However, tidal and fluvial processes acting in these depositional environments can introduce significant levels of heterogeneity which can lead to uncertainties in predicting the distribution and the lateral continuity of reservoir facies. Even though wave-dominated shallow marine reservoirs are traditionally considered to be continuous and tank-like, recent studies show that such systems can also be highly heterogeneous, which can lead to unexpected problems in reservoir connectivity prediction and compart-mentalization. Work by the research group attempts to quantify such level of heterogeneity by using modern and ancient analogues, and to apply the outcomes to stochastic reservoir models.
Shallow marine research undertaken by RARG has been dominated by two phases of the industry-funded WAVE Consortium (2008-2015), which aims to better characterise mixed-influence coastal depositional environments and to analyse the potential impact of heterogeneities (shales and cemented zones) on reservoir connectivity and compartmentalization and how it can best be predicted and mitigated in the subsurface. WAVE research is ongoing and a proposal for Phase III has been circulated. A major modern analogue focus for this research into mixed-process systems has been the Mitchell River delta, Gulf of Carpentaria, Australia. Other marginal-marine research undertaken by RARG members has focused in two key areas: outcrop analogue description and interpretation from the Neoproterozoic Bonney Sandstone of the Flinders Ranges, and an investigation of marginal lacustrine deposition utilising modern analogue (Lake Yamma Yamma, Lake Eyre Basin), outcrop (Dakota Formation of the Lake Cretaceous Western Interior Seaway, USA) and subsurface data (well and seismic).