Detection of hydrocarbon seeps using remote sensing technique in the Rufiji onshore basin
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Date
2017
Authors
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Publisher
The University of Dodoma
Abstract
Hydrocarbon seeps cause chemical and mineralogical alterations at the surface, which can be identified geologically but also detected by remote sensing techniques. This work aimed at detecting mineral alteration induced by hydrocarbon seeps in a sandstone formation in Rufiji basin (Wingayongo), South Coast Tanzania. For this study, rock samples collected during fieldwork were petrographically analysed and the multispectral ASTER data was downloaded and utilized to characterize the identified alteration minerals in the Wingayongo sandstone. The area is covered by medium-grained gray to brown chocolate bituminous sandstone, which acts as reservoir rock but with no cap rock overlaying it. The contact between sandstone layers was identified and defined as the main source of hydrocarbon migration pathways. The large area of this sandstone is bleached indicating discolouration of ferric iron into ferrous iron. Elemental sulfur greenish yellow in colour together with sulphur smell was identified around the seep. Petrographic analysis (XRD and Thin Section) have shown the high value of ferrous iron but there was no evidence of clay (kaolinite) or carbonate minerals. Remote sensing spectral signature through band ratio enhancement indicated the presence of siderite material, altered vegetation together with un-vegetation signals. The observed signals are potential vectors for oil seeps. Other prospective areas were identified using similar spectral signals in the surrounding areas. The use of more than one data-set together with the use of a more powerful remote sensing technique is recommended to overcome challenges in interpretation and issues of scale of alteration and other controversors.
Description
Dissertation (MSc Petroleum Geoscience)
Keywords
Hydrocarbon seeps, Mineralogical alterations, Mineral alterations, Sandstone, Rufiji, Tanzania, Oil seeps, Hydrocarbon, Hydrocarbons, Sandstone formation, Remote sensing, Remote sensing techniques
Citation
Mruma, A. (2017). Detection of hydrocarbon seeps using remote sensing technique in the Rufiji onshore basin. Dodoma: The University of Dodoma