SOLID GEO MECHANICAL INVESTIGATION OF THE EFECT OF SALT CREEP ON CASING STABILITY USING FNITE ELEMENT METHOD: A CASE STUDY
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Date
2020-06-22
Authors
Mohammadi, Saheb
Sedaghatzadeh, Mostafa
Pourafshary, Peyman
Journal Title
Journal ISSN
Volume Title
Publisher
SN Applied Sciences
Abstract
The salt formation creeping can signifcantly afect the casing stability, because of the changes in mechanical and geome chanical parameters. The creeping of Gachsaran salty formation in the south part of Iran has infuences on wells drilled
in the region, which should be carefully considered in the casing design process. In this study, the fnite element analysis
technique was applied to study the alteration in mechanical/geomechanical parameters of a well in this formation. The
accuracy of the methodology was validated by data available from the reduction in wellbore diameter of another well
in the formation. Diferent scenarios were studied to analyze the efect of geomechanical parameters on stress, plastic
strain, and casing diameter for a cased cemented well and a well completed with two casings. The efect of mechanical
parameters on casing collapse was studied, where casing eccentricity, ovality, and slenderness ratio were also considered.
Our simulation studies showed that casing stability in salty formations is strongly afected by geomechanical and pipe
mechanical parameters. To reduce the severity of the casing collapse in salty formation, it is recommended to complete
the well with two casings. Our study showed that, this arrangement reduces the plastic strain and the change in casing
diameter signifcantly For a safe casing design, efect of mechanical parameters should be also considered. Efects of
parameters such as ovality, eccentricity, and slenderness ratio are noticeable, for example, 2% ovality and 2% eccentricity
in L-80 casing, lead to increase in the plastic strain from 0.112 to 0.31 and 0.3, and the overall diameter reduction from
0.455″ to 0.685″ and 0.535″, respectively.
Description
Keywords
Type of access: Open Access, Salt creep, Casing stability, Casing design, Solid mechanics, Geomechanics, Finite element method
Citation
Mohammadi, S., Sedaghatzadeh, M., & Pourafshary, P. (2020). Solid-geo-mechanical investigation of the effect of salt creep on casing stability using finite element method: a case study. SN Applied Sciences, 2(7). https://doi.org/10.1007/s42452-020-3083-7