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dc.date.accessioned2013-03-12T09:02:33Z
dc.date.available2013-03-12T09:02:33Z
dc.date.issued2008en_US
dc.date.submitted2008-06-25en_US
dc.identifier.citationWoyessa, Asfaw Tenna. Depositional environment, sequence stratigraphy and reservoir properties of an Eocene mixed siliciclastic - carbonate succession in the Ainsa Basin, Southern Pyrenees. Masteroppgave, University of Oslo, 2008en_US
dc.identifier.urihttp://hdl.handle.net/10852/12486
dc.description.abstractABSTRACT Mixed siliciclastic carbonate rocks of Lower Eocene age are studied in the eastern part of the Ainsa Basin, Southern Pyrenees. These deposits generally show an upward coarsening and shoaling trend followed by deepening trend. Nine facies identified in the study area have been grouped into four facies associations formed within a carbonate ramp platform. These are: (a) low-angle cross-bedded siliciclastic sandstone and micritic limestone; (b) crossbedded to horizontally laminated carbonate rich sandstone; (c) amalgamated/interbedded carbonate rich sandstone; and (d) structureless siltstone and mudstone and micritic limestone. The succession has been classified into three informal units: the lower-, middle-, and upper-units. The lateral extent and the architectural style of the deposits in each unit are very variable. Nummulites dominate the biota with minor occurrences of bivalves and plant fragments.Most part of the carbonates in the study area is interpreted to be produced by nummulites with some siliciclastic input in the shallower part of the platform. Nummulite shells were reworked, fragmented and redistributed later by basinal current processes. The platform has been divided into inner-, mid-, and outer-ramp positions. In the middle unit there is a systematic variation in depositional environment from northern- to southern- part of the study area that reflects northward shallowing and/or the existence of dominant oceanographic currents that drifted towards north, or a combination of both factors. The middle unit represents a highstand systems tract with a possible highstand carbonate shedding into the deeper part of the basin. The deposits are interpreted to be controlled by both autogenic and allogenic factors. While in situ carbonate production by nummulites and oceanographic currents are included in the autogenic controls, tectonics, eustacy, and climate are thought to have played a major role in allogenic factors. Tropical to seasonal subtropical climatic condition of the study area during the Eocene, which created a conducive environment for nummulites, augmented by reduced siliciclastic sediment supply led to progradation for the mixed-siliciclastic carbonate deposits in the middle unit. Later, transgression must have occurred that caused deposition of carbonate rich mudstone of the upper unit, combined with shoreface retreat. Poor vertical connectedness and lateral discontinuity of carbonate rich sandstones, very fine grain size and with most interparticle pore spaces filled by different minerals make this type of carbonate ramp platform succession to represent a low-permeability reservoir of restricted reservoir qualities.eng
dc.language.isoengen_US
dc.subjectpetroleumsgeologi grunnmarine avsetninger avsetningsmiljø reservoar egenskaper silisiklastisk-karbonat sørlige Pyreneeneen_US
dc.titleDepositional environment, sequence stratigraphy and reservoir properties of an Eocene mixed siliciclastic - carbonate succession in the Ainsa Basin, Southern Pyreneesen_US
dc.typeMaster thesisen_US
dc.date.updated2009-04-14en_US
dc.creator.authorWoyessa, Asfaw Tennaen_US
dc.subject.nsiVDP::450en_US
dc.identifier.bibliographiccitationinfo:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft.au=Woyessa, Asfaw Tenna&rft.title=Depositional environment, sequence stratigraphy and reservoir properties of an Eocene mixed siliciclastic - carbonate succession in the Ainsa Basin, Southern Pyrenees&rft.inst=University of Oslo&rft.date=2008&rft.degree=Masteroppgaveen_US
dc.identifier.urnURN:NBN:no-20111en_US
dc.type.documentMasteroppgaveen_US
dc.identifier.duo80651en_US
dc.contributor.supervisorProfessor Johan Petter Nysuen, Professor Roy Gabrielsen and Dr. Micheal Heermans,en_US
dc.identifier.bibsys092047971en_US
dc.identifier.fulltextFulltext https://www.duo.uio.no/bitstream/handle/10852/12486/1/WoyessaxxAsfawxTenna.pdf


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