Restoration of annular zonal isolation using localized casing expansion (LCE) technology: A proof of concept based on laboratory studies and field trial results

• Published in: Journal of petroleum science & engineering Vol. 197; p. 108103
• Main Authors: Wolterbeek, T.K.T., Cornelissen, E.K., Nolan, S., Todea, F., Stam, W., Roggeband, S.M., Dam, L., van Riet, E.J., Ruckert, F., Keultjes, W.J.G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2021
• Subjects: Annular fluid migration; Casing expansion; Surface casing vent flow; Sustained casing pressure; Well abandonment; Well integrity; Sustained casing pressure; Surface casing vent flow; Casing expansion; Annular fluid migration; Well integrity; Well abandonment
• ISSN: 0920-4105; 1873-4715
• DOI: 10.1016/j.petrol.2020.108103

Sustained casing pressure (SCP), surface casing vent flow (SCVF) and other expressions of annular fluid migration are widely encountered zonal isolation issues. Conventional solutions for SCP/SCVF include perforate and squeeze cementing, or section milling and recementing. Regrettably, the former approach shows only limited success rates, while the latter involves time and cost intensive operations that require a drilling rig. We will show that localized casing expansion (LCE) technologies offer promising alternatives, enabling rigless remediation of annular fluid migration. The LCE concept involves imposing permanent deformation on the casing pipe to locally enlarge its diameter. The associated annular volume reduction causes closure of defects such as micro-annuli and cement fractures, plus potentially even larger voids, and results in an overall densification of the cement microstructure. The Shell-developed Local Expander tool is e-line deployable and imposes the required casing deformation in a mechanical, fully controlled manner. Tailored-shaped energetic charges offer valuable supplementary means for achieving expansion. We will demonstrate the sealing effectiveness of LCE in both laboratory experiments and field trials, describe how the radial deformation impacts the casing and cement, and generally discuss the current state of knowledge, capabilities and limitations of LCE with respect to SCP/SCVF remediation. •New method for restoring annular cement zonal isolation prior to well abandonment.•Technology locally imposes permanent radial enlargement of the casing.•This expansion causes closure of annular seepage paths and cement densification.•Two downhole tools for achieving local casing expansion were developed and evaluated.•These tools successfully eliminated annular gas migration along six trial wells.