Numerical estimation of structural integrity of salt cavern wells.
conference paper
Finite element analyses were performed to estimate axial deformation of cavern wells due to gas storage operations in solution-mined salt caverns. Caverns shrink over time due to salt creep and the cavern roof subsides potentially threatening well integrity. Cavern deformation, deformation of salt surrounding the cavern and impacts on well integrity were quantified using a generic geomechanical finite element model that resembles gas storage operations in solution-mined caverns in the Netherlands. The analysis results show that the largest deformation occurs at the floor and the lowest section of the side wall of a cavern, while the roof deformation is typically one order of magnitude smaller than those of the floor and the wall. The predicted vertical tensile strains that can cause tensile fracturing of well cement develop in the lowest 40-100m-long section of the well. The last cemented casing, typically set at a few tens of meters above the cavern roof, can therefore be affected by the vertical tensile strains that could damage cement sheath and threaten well integrity. The actual borehole construction need to be included in numerical models to investigate in more detail the impact of salt creep on wells in site- and configuration-specific underground gas storage projects.
TNO Identifier
572498
Publisher
American Rock Mechanics Association ARMA
Article nr.
ARMA 16-479
Source title
Proceedings of the 50th US Rock Mechanics / Geomechanics Symposium (ARMA), Houston, TX, 26-29 June 2016
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