Evaluation of wellbore cement integrity for groundwater protection
Publikationen: Thesis / Studienabschlussarbeiten und Habilitationsschriften › Masterarbeit
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2015.
Publikationen: Thesis / Studienabschlussarbeiten und Habilitationsschriften › Masterarbeit
Harvard
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TY - THES
T1 - Evaluation of wellbore cement integrity for groundwater protection
AU - Thonhofer, Christoph
N1 - embargoed until null
PY - 2015
Y1 - 2015
N2 - A lack of well integrity and resulting gas migration through the cemented sections of a well occurs in a large number of wells and can cause severe problems in either the well itself or, through contaminating cross flow, in the formation around the well. Also “Shallow Gas”, which naturally occurs in low depths, poses a potential threat. Especially the contamination of the ground water bearing zones in an area is one thing that must not be underestimated and should definitely be avoided. The quality of cement bonding is usually measured with so called “Bond Logs”. The working principles and accuracy of the most common log types will be discussed in order to clarify their strengths and limitations. This thesis will then investigate the reasons for insufficient cement bonding and micro channels in the cement which allow gas migration in the first place, with a focus on the surface casing section. Theoretical concepts of bonding or integrity models will be discussed to set boundary conditions for possible future FE simulations. Also possible experiments which could be helpful to improve wellbore integrity will be proposed. The main purpose is to increase awareness of the importance of proper cement placement within the well and the importance of the so called Minimum Bonded Interval.
AB - A lack of well integrity and resulting gas migration through the cemented sections of a well occurs in a large number of wells and can cause severe problems in either the well itself or, through contaminating cross flow, in the formation around the well. Also “Shallow Gas”, which naturally occurs in low depths, poses a potential threat. Especially the contamination of the ground water bearing zones in an area is one thing that must not be underestimated and should definitely be avoided. The quality of cement bonding is usually measured with so called “Bond Logs”. The working principles and accuracy of the most common log types will be discussed in order to clarify their strengths and limitations. This thesis will then investigate the reasons for insufficient cement bonding and micro channels in the cement which allow gas migration in the first place, with a focus on the surface casing section. Theoretical concepts of bonding or integrity models will be discussed to set boundary conditions for possible future FE simulations. Also possible experiments which could be helpful to improve wellbore integrity will be proposed. The main purpose is to increase awareness of the importance of proper cement placement within the well and the importance of the so called Minimum Bonded Interval.
KW - bond log
KW - Evaluierung der Zementation
KW - Mindeststrecke für Zementation
KW - well integrity
KW - minimum bonded interval
KW - bond logs
KW - cement sheath evaluation
M3 - Master's Thesis
ER -