Print this pageAAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Seismic Geomorphology and Stratigraphy of Distributary Channels and Incised Valleys of the Mungaroo Delta Plain, Wa-390-P, Exmouth Plateau, North Carnarvon Basin, Western Australia
Jon
Minken1; Josh Miller2; Yohan Kusumanegara1; Dean Griffin1
(1) Hess Australia Exploration, Perth, WA, Australia.
(2) Hess Exploration Production Technology, Houston, TX.
Characterization of detailed channel networks in the thick (>1 kilometer), retrogradational, delta plain succession of the Carnian and Norian Mungaroo Formation, Exmouth Plateau, North Carnarvon Basin reveals a complex succession of predominately distributary channels and incised valleys. Identification of the channels depositional environment relied on integration of 3D seismic, well logs, sidewall cores and biostratigraphy. Distributary channels form low sinuosity, single storey sand bodies that are less than 15 meters thick and limited to 1 kilometer in width within an overall dispersive pattern. Incised valleys are multistory reflecting a complex history of erosion and deposition resulting in sand bodies in excess of 15 meters and widths larger than 1 kilometer.
Distributary channels evolved into incised valleys with a decrease in accommodation, increase in sediment supply and/or increase in fluvial discharge causing entrenchment into the delta plain. Temporarily, the resulting incised valley network will exhibit a morphology similar to the original distributive pattern. Incision is facilitated and maintained by knickpoint propagation upstream from the delta front. If dissection of the delta plain continues, the fluvial discharge of subordinate valley systems will be captured causing abandonment of the lesser valleys and development of a larger valley system. Horizon slices and well log data reveal that post incision the delta plain is demarcated by valleys of different widths, depths and morphologies reflecting different degrees of incision.
High reservoir quality sands within both the distributary channels and incised valleys makes them attractive exploration targets in the North Carnarvon Basin. Pre-drill identification of distributary channels and incised valleys facilitates a better understanding of the reservoir container. The greater widths and thicknesses associated with the incised valleys creates the potential for a larger hydrocarbon accumulation.