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Article: DEM modeling of hydraulic fracturing in permeable rock: influence of viscosity, injection rate and in-situ states

TitleDEM modeling of hydraulic fracturing in permeable rock: influence of viscosity, injection rate and in-situ states
Authors
Issue Date2018
PublisherSpringer Verlag.
Citation
Acta Geotechnica, 2018, v. 13 n. 5, p. 1187-1202 How to Cite?
AbstractHydraulic fracturing in permeable rock is a complicated process which might be influenced by various factors including the operational parameters (e.g., fluid viscosity, injection rate and borehole diameter) and the in situ conditions (e.g., in situ stress states and initial pore pressure level). To elucidate the effects of these variables, simulations are performed on hollow-squared samples at laboratory scale using fully coupled discrete element method. The model is first validated by comparing the stress around the borehole wall measured numerically with that calculated theoretically. Systematic parametric studies are then conducted. Modeling results reveal that the breakdown pressure and time to fracture stay constant when the viscosity is lower than 0.002 Pa s or higher than 0.2 Pa s but increases significantly when it is between 0.002 and 0.2 Pa s. Raising the injection rate can shorten the time to fracture but dramatically increase the breakdown pressure. Larger borehole diameter leads to the increase in the time to fracture and the reduction in the breakdown pressure. Higher in situ stress requires a longer injection time and higher breakdown pressure. The initial pore pressure, on the other hand, reduces the breakdown pressure as well as the time to fracture. The increase in breakdown pressure with viscosity or injection rate can be attributed to the size effect of greater tensile strength of samples with smaller infiltrated regions.
Persistent Identifierhttp://hdl.handle.net/10722/259210
ISSN
2015 Impact Factor: 2.426
2015 SCImago Journal Rankings: 1.818

 

DC FieldValueLanguage
dc.contributor.authorDuan, K-
dc.contributor.authorKwok, CY-
dc.date.accessioned2018-09-03T04:03:11Z-
dc.date.available2018-09-03T04:03:11Z-
dc.date.issued2018-
dc.identifier.citationActa Geotechnica, 2018, v. 13 n. 5, p. 1187-1202-
dc.identifier.issn1861-1125-
dc.identifier.urihttp://hdl.handle.net/10722/259210-
dc.description.abstractHydraulic fracturing in permeable rock is a complicated process which might be influenced by various factors including the operational parameters (e.g., fluid viscosity, injection rate and borehole diameter) and the in situ conditions (e.g., in situ stress states and initial pore pressure level). To elucidate the effects of these variables, simulations are performed on hollow-squared samples at laboratory scale using fully coupled discrete element method. The model is first validated by comparing the stress around the borehole wall measured numerically with that calculated theoretically. Systematic parametric studies are then conducted. Modeling results reveal that the breakdown pressure and time to fracture stay constant when the viscosity is lower than 0.002 Pa s or higher than 0.2 Pa s but increases significantly when it is between 0.002 and 0.2 Pa s. Raising the injection rate can shorten the time to fracture but dramatically increase the breakdown pressure. Larger borehole diameter leads to the increase in the time to fracture and the reduction in the breakdown pressure. Higher in situ stress requires a longer injection time and higher breakdown pressure. The initial pore pressure, on the other hand, reduces the breakdown pressure as well as the time to fracture. The increase in breakdown pressure with viscosity or injection rate can be attributed to the size effect of greater tensile strength of samples with smaller infiltrated regions.-
dc.languageeng-
dc.publisherSpringer Verlag. -
dc.relation.ispartofActa Geotechnica-
dc.rightsThe final publication is available at Springer via http://dx.doi.org/[insert DOI]-
dc.titleDEM modeling of hydraulic fracturing in permeable rock: influence of viscosity, injection rate and in-situ states-
dc.typeArticle-
dc.identifier.emailDuan, K: kangduan@hku.hk-
dc.identifier.emailKwok, CY: fkwok8@hku.hk-
dc.identifier.authorityKwok, CY=rp01344-
dc.identifier.doi10.1007/s11440-018-0627-8-
dc.identifier.hkuros289122-
dc.identifier.volume13-
dc.identifier.issue5-
dc.identifier.spage1187-
dc.identifier.epage1202-
dc.publisher.placeGermany-

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