An Investigation of the Controls on the Number and Spacing of Coastal Channel Systems in Madagascar
Bachelor of Science (Petroleum Geology and Geophysics) 2015
Australian School of Petroleum
The University of Adelaide
Coastal channel systems can introduce heterogeneity into hydrocarbon reservoir rocks. If this heterogeneity is not properly incorporated into reservoir models, hydrocarbon accumulations may not be optimally exploited. 3-dimensional seismic data is often unable to image channels, thus the reservoir models must be populated with channels by other means. This research analyses the spacing of coastal channels around the modern Madagascan coastline and investigates the spacing, and the controls on spacing of these channels. The aim is to build some statistical relationships about channel spacing that can be used to populate reservoir models for which Madagascar is a reasonable analogue of. Madagascar has 793 channels that breach the coastline, with an average spacing of 5.6 km. The east coast of Madagascar has an average channel spacing of 10.1 km, the south west coast channel spacing is 22.9 km, central west coast is 4.6 km and the spacing in large embayments averages 2.1 km. In wave dominated areas, channels form mainly through fluvial processes, and as a result the coastal channel spacing is a function of fluvial spacing. In areas in which reefs attenuate the wave energy reaching the coast, tide dominated channels can form too, reducing the average spacing. Average channel spacing decreases as tidal strength increases relative to wave strength in non-fluviatile channels. As wave dominated systems often form the best reservoir, further work is required to ascertain the controls on fluvial channel spacing to improve our modelling abilities for these areas.