Effect of Clay Fraction on Thermal-hydro-mechanical Responses of Soft Mudrocks

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atmire.migration.oldid3609
dc.contributor.advisorWong, Ron C. K.
dc.contributor.authorLi, Biao
dc.date.accessioned2015-09-24T19:50:19Z
dc.date.embargolift2016-02-22T07:00:00Z
dc.date.issued2015-09-24
dc.date.submitted2015en
dc.description.abstractDue to their low permeability, soft mudrocks often serve as geological seals for thermal recovery and nuclear waste disposal projects which are accompanied by thermal-hydro-mechanical (THM) coupled processes. The studies on the temperature, pore pressure, strain and stress developments in soft mudrock formations are the fundamentals of evaluating the risks such as wellbore collapse, casing failure and leakage through sealing rocks. Despite their importance, the variation in clay fraction and anisotropic nature of soft mudrocks has challenged the theoretical modeling and prediction of their THM responses. In this research, new approaches or models are proposed to investigate the effect of clay fraction on THM responses of soft mudrocks with emphasis on the micro-scale mechanisms. A cm-model is proposed to quantify structural states of soft mudrocks, which are dependent on clay fractions and porosities. Geomechanical properties and oriented fabric distributions are quantitatively related to structural states of soft mudrocks. Theoretical modelings on anisotropic hydraulic, static transversely isotropic (TI) elastic, and anisotropic thermal strain properties of soft mudrocks incorporating changes in the oriented fabric distribution are conducted. A modified Kozeny-Carman model is proposed to estimate the anisotropic permeability of soft mudrocks with different clay fractions. The directional tortuosity is directly linked to the fabric orientation distributions of soft mudrocks. For soft mudrocks with the similar mineralogy and porosity, logarithmic values of permeabilities decrease linearly with the increase of clay fraction. The static TI elastic properties of soft mudrocks are modeled using a differential effective-medium (DEM) approach. The elastic anisotropy is linked to the oriented fabric distribution by the Voigt approximation. A compositional thermal strain model is developed to interpret the anisotropic expansion or contraction behavior in soft mudrocks using cm-model. The compositional thermal strain model is validated by a series of experimental results. High clay fraction soft mudrocks are on the risk of having thermal contraction behavior which comes from clay dehydration or thermal plastic strain. Thermally induced tensile fracturing behavior in a high clay fraction soft mudrock is also investigated using analytical, experimental and numerical approaches. Above mentioned results are used in the comprehensive wellbore stability analysis of practical thermal recovery wells in Cold Lake area, Alberta.en_US
dc.identifier.citationLi, B. (2015). Effect of Clay Fraction on Thermal-hydro-mechanical Responses of Soft Mudrocks (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25794en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/25794
dc.identifier.urihttp://hdl.handle.net/11023/2491
dc.language.isoeng
dc.publisher.facultyGraduate Studies
dc.publisher.institutionUniversity of Calgaryen
dc.publisher.placeCalgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subjectGeophysics
dc.subjectEngineering--Civil
dc.subjectGeotechnology
dc.subject.classificationthermal-hydro-mechanical propertiesen_US
dc.subject.classificationtransversely isotropicen_US
dc.subject.classificationwellbore stabilityen_US
dc.titleEffect of Clay Fraction on Thermal-hydro-mechanical Responses of Soft Mudrocks
dc.typedoctoral thesis
thesis.degree.disciplineCivil Engineering
thesis.degree.grantorUniversity of Calgary
thesis.degree.nameDoctor of Philosophy (PhD)
ucalgary.item.requestcopytrue
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