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Technical Paper: Flexible Cement Improves Wellbore Integrity for Steam Assisted Gravity Drainage (SAGD) Wells
Paper 117859
Abstract
Well integrity is a key requirement for continuing heavy oil development and production. Cement sheath integrity is crucial
to maintaining zonal isolation, which prevents unwanted fluid migration, especially oil, gas and steam, outside of the
wellbore. Current commercial production techniques in heavy oil use steam to provide heat to mobilize oil and allow
production. These production techniques apply significant stress to the cement sheath which could lead to cement sheath
failure. A computer simulation assessing the stress in the cement sheath is presented. Flexible cement systems can be
designed so that the cement sheath can withstand the expected stresses during the life of the well.
Preventing cement breakdown can be achieved by improving the installation practices and by assessing and reducing the
stresses imposed on the cement during the life of the well.
A case history detailing the installation of a flexible cement system in a SAGD production well is presented. Once a flexible
cement system has been selected, careful planning and process control is required to deliver the system with the desired
properties. Best practices must be used for placement of the system in the annulus. Industry best practices, especially the use
of centralizers, viscous fluid spacers and pipe movement were employed. Excellent zonal isolation is achieved with the
flexible cement system.
Several challenges also present themselves for the installation and also the evaluation of the cement sheath. Centralization
and hole size play an important role in the placement of the cement system in the annulus. Assessing the well zonal isolation
integrity is the next step once the cement is in place. Operating parameters for a particular well can be determined using
numerical modelling to simulate the stress that the cement sheath will be exposed to.
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