Sub-surface geology, hydrothermal alteration and 3D modelling of wells LA-9D and LA-10D in the Aluto Langano geothermal field, Ethiopia

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dc.contributor.author Sisay, Selamawit Worku is
dc.date.accessioned 2017-02-01T11:42:31Z
dc.date.available 2017-02-01T11:42:31Z
dc.date.issued 2016
dc.identifier.isbn 9789979684107
dc.identifier.issn 16707427
dc.identifier.issn 1670-7427
dc.identifier.uri http://hdl.handle.net/10802/12462
dc.description Námsritgerð MSc við Háskóla Íslands is
dc.description.abstract Aluto Langano geothermal field is located in the Aluto volcanic complex (AVC), within the Central Main Ethiopian Rift System (CMERS). AVC is a silicic peralkaline complex, which is affected by Wonji fault belt (WFB), trending NNESSW. Ten exploratory wells (LA-1 to LA-10D) have been drilled in Aluto Langano geothermal field, with a maximum depth of 2500 m and maximum measured temperature of 335°C. This study focused on sub-surface geology and hydrothermal alteration of wells LA- 9D and LA-10D. The wells were drilled directionally on the top of AVC. Data form neighbouring wells (wells LA-3 to LA-8) are used for comparison purposes. Lithologies that are found in the study wells, identified with the aid of binocular microscopy and petrographic microscopy, are pyroclastics, silicic tuff and breccia, sediments, rhyolite, trachyte, basalt and ignimbrite, while ICP-OES analyses also led to the identification of very scarce and thin layers of trachyandesite, basaltic trachyandesite, trachydacite, basaltic andesite and andesite units. Hydrothermal alteration minerals are found as replacement of primary minerals and as fillings of veins and vesicles. Four alteration zones are recognized in both study wells, and include an unaltered zone, smectite zone, illite/chlorite zone and illite/chlorite/epidote zone. Eight feed zones (with one major and seven minor) were identified in well LA-9D and seven (one major with six minor) feed zones in LA-10D are observed. Most of the feed zones are located in fractured basaltic units. The highest temperature recorded was more than 300°C in well LA-9D below 1560 m depth, and below 1600 m in LA-10D, the recorded temperature indicated is more than 300°C. Both wells appear to be in the upflow zone of the system. is
dc.format.extent viii, 75 bls. is
dc.language.iso en
dc.publisher Jarðhitaskóli Háskóla Sameinuðu þjóðanna is
dc.relation.ispartofseries United Nations University., UNU Geothermal Training Programme, Iceland. Report ; 2016:06
dc.relation.uri http://os.is/gogn/unu-gtp-report/UNU-GTP-2016-06.pdf
dc.subject Jarðhiti is
dc.subject Jarðfræði is
dc.subject Borholur is
dc.subject Eþíópía is
dc.title Sub-surface geology, hydrothermal alteration and 3D modelling of wells LA-9D and LA-10D in the Aluto Langano geothermal field, Ethiopia en
dc.type Bók is
dc.identifier.gegnir 991007934279706886


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