AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Distributive Fluvial Systems in the Continental Rock Record: Implications for Reservoir Development in Alluvial Systems
(1) Geology & Petroleum Geology, University of Aberdeen, Aberdeen, United Kingdom.
(2) Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM.
(3) Geology, Royal Holloway, University of London, London, United Kingdom.
Studies of actively aggrading sedimentary systems in continental settings show that deposition is dominated by distributive fluvial systems (DFS). Studies of modern day examples using remotely sensed imagery and field data have allowed the development of a series of facies models that differ significantly from tributary-dominated systems on which current facies models are based. In particular modern DFS are characterised by a downstream decrease in discharge and channel size with concomitant changes in grain size and facies types in contrast to the tributary model which predicts the opposite. The implications of these observations are that facies types and alluvial reservoir quality and connectivity will vary significantly within a sedimentary basin in a predictive manner. If an understanding of the large scale context of an alluvial system can be determined (i.e. size of basin, location of basin margin etc.), then a predictive framework for reservoir development can be established. Predictive models derived from remotely sensed data are valuable, but their relevance needs to be assessed through comparison with the rock record. Here we present outcrop data from a number of different continental basins including the Miocene of the Ebro Basin, Spain, the Permian Cutler Formation, Triassic Chinle Formation and Jurassic Morrison Formation all from SW USA to test the relevance of remotely sensed data to outcrop studies. Observations from these outcrop datasets indicate that predictive changes in alluvial architecture do occur down system from largely channelized to non-channelized deposits, but that the presence of an axial fluvial system may modify these relationships.