This research is focused on mapping the geometries of surface and subsurface landforms and their relationship in the Niger Delta. Landforms on the surface are studied to improve our understanding of the spatial distribution of buried landforms. GIS techniques are applied to high resolution Landsat and SPOT imagery to map surface landforms, a necessary step in order to improve and better constraint subsurface modelling. Also, attributes from three dimensional seismic data are used to map buried landforms. Both techniques are focused on mapping the spatial distribution of landforms and analysis of their shape, size, orientation, connectivity and density. Results on the study of fluvial channels, point bars, braid bars, tidal channels, beach-barrier islands and spits are presented in this thesis. The updated map of the subarial Niger Delta covers an area of 70,000 km2. Tidal channel width increases exponentially toward the coast; in contrast the fluvial channel width decreases linearly downstream. Tidal channels are interconnected within a complex network. The tidal channels are wider in the East and West Flanks while in the centre they are narrower. Here, channel mouths are at a high angle with the coastline because of a combined effect of high sediment flux and longshore drift. Tidal channels are therefore grouped into four distinct zones; the West (Forcados River Zone), the Central (Nun River Zone), the East (Sombreiro River Zone) and the Far-East (Cross River Zone) based on their channel morphology and density. Each lobe is influenced differently by the interaction of fluvial, tidal and wave-related processes. This implies that it is appropriate to look at the Niger Delta as an amalgam of deltas geographically separated into four lobes. The morphology of the beaches also supports the considered reclassification, as they show distinct morphologies within each of the four lobes. Beaches are longer and wider on the eastern and western flanks and thin out towards the central lobe due to high sediment influx and wave reworking. Parallel channels form between scrolls and ridges and are prominent in areas where tidal influence does not extend far into the land. The correlation between the geometries of the surface and subsurface landforms is very strong and indicates that where subsurface details are missing, it is acceptable and reasonable to use surface information to make predictions about the subsurface. The result will help in constraining parameters used in modelling of geometric and dimensional properties of reservoirs and to better manage uncertainties, all elements relevant to the oil and gas industry.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:606482 |
| Date | January 2014 |
| Creators | George, Chinotu Franklin |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=211213 |
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