Fluvio-Lacustrine Incision and Deltaic Processes: Insights From an Integrated Sequence Stratigraphic and Modern Analogue Approach, Early Cretaceous, Eromanga Basin, Australia
Fluvio-lacustrine incised and deltaic deposits contain globally significant resources but are understudied and underdeveloped compared to those of marine-paralic environments, representing a significant opportunity to deliver energy for the future. A development challenge with such fields is the limited amount of subsurface data; with limited data, many geological models can fit. A robust geological interpretation, enhanced with process-based insights from modern analogues, can mitigate this problem. In this study a modern analogue was used to provide insight into sedimentary processes in fluvio-lacustrine environments, in order to maximise development potential for an Early Cretaceous field within the Eromanga Basin. 3D seismic, wireline, core and production data were used to develop a depositional model for the field. Multiple sequences of incised fluvial, deltaic and shoreline sediments were interpreted to have been deposited in an endorheic lacustrine setting, with deposition predominantly controlled by cyclic changes in lake level. With a maximum stacked sandbody thickness of 15 m, the reservoir could not be seismically imaged in high resolution. In order to develop predictive models for the field, a process-based approach including the investigation of a modern fluvio-lacustrine system was used. Modern analogue fieldwork was undertaken at Lake Yamma Yamma (690 km2), central Australia. Important results for incision morphodynamics and characteristics, as well as sedimentary response to water fluctuations including forced regression and transgressional estuarine back-filling are presented. Results highlight the amplification of climate records in endorheic lakes, processes and controls for incision and the influence of regional tectonics on sediment-body characteristics and morphology. Findings are placed in context with continental sequence stratigraphic and lake-basin type models from published literature in order to better develop our subsurface interpretation. This study presents new data from a previously unstudied modern lake and new interpretation for a previously understudied field deposited in a fluvio-lacustrine setting. Insights into depositional processes for coeval incised valley and lacustrine delta environments are presented. Future work will include investigation of other fluvio-lacustrine analogues and the integration of geoscience and petroleum engineering concepts to improve static and dynamic models for the field.
AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015