Show simple item record

dc.contributor.advisorPrior, David
dc.contributor.authorLister, Aaron
dc.date.available2018-10-30T21:50:48Z
dc.date.copyright2018
dc.identifier.citationLister, A. (2018). Analysis of Reservoir Fracture Sealing in an Active Geothermal System, Kawerau Geothermal Field, New Zealand (Thesis, Master of Science). University of Otago. Retrieved from http://hdl.handle.net/10523/8496en
dc.identifier.urihttp://hdl.handle.net/10523/8496
dc.description.abstractThe microscopic crystallographic structures of geothermal minerals precipitated in fractures located within active geothermal reservoirs have the potential to record significant information concerning the kinematics of fracture formation and sealing over time. It is vitally important to understand these processes when developing reservoir models, especially when defining the influences of secondary permeability for high temperature geothermal systems. This study highlights a multi-staged analysis of the mineral calcite that has been identified to control permeability in the reservoir of the Kawarau Geothermal Field, TVZ, New Zealand. Outlined is the methods of carrying out EBSD, EDX, Cathodoluminesce, ICPMS and a variety of other techniques to understand the process of fracture sealing using field samples. The initial study of the fracture identified two separate sealing mechanisms occurring between the different phases of calcite deposition. In addition the two phases of calcite deposition had different internal crystallographic structure and elemental composition. A 3-D analysis was then carried out by serial sectioning, this includes the process of 3-D EBSD by serial sectioning and builds on the initial findings. Finally the ICPMS analysis was unable to accurately date the bladed calcite, due to inadequate U-Th ratios. However, it did show that it is possible to carry high-precision geochemical analysis on geothermally precipitated bladed calcite. The Eu anomaly identified in the calcite highlights the complex history of geothermal fluids in the reservoir of Kawerau. These multiple aspects assist in providing a deeper understanding of how the geothermal system has changed over time. By reconstructing calcite filled fractures using a range of alternative techniques in 2-D and 3-D, an advanced insight into the complex nature of vein crystal growth evolution and related chemical patterns can be extracted. These can then be used to constrain how veins control fracture permeability over time on a microscopic scale.
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherUniversity of Otago
dc.rightsAll items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectGeothermal
dc.subjectKawearu
dc.subjectCalcite
dc.subjectvein
dc.subjectTVZ
dc.titleAnalysis of Reservoir Fracture Sealing in an Active Geothermal System, Kawerau Geothermal Field, New Zealand
dc.typeThesis
dc.date.updated2018-10-30T20:30:03Z
dc.language.rfc3066en
thesis.degree.disciplineGeology
thesis.degree.nameMaster of Science
thesis.degree.grantorUniversity of Otago
thesis.degree.levelMasters
otago.openaccessOpen
 Find in your library

Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record