Centralizers to minimise the risk of buckling
Structural internal centralizers are run on internal strings where a standard cementing (bow-type) centralizer is inadequate as indicated by riser and completion analysis. This type of centralizer is required when there are concerns over the structural integrity of the inner strings and when the analysis shows a risk of buckling.
Claxton’s internal centralizers are constructed in two halves, with two joining flanges on each half for easy installation around plain casing.
The design considers the effect of test pressure in the inner casing as well as the medium they will be exposed to throughout their life. Internal centralizers are commonly designed for radial loads between 5-10 tonnes but they can also be designed for high lateral loads of over 20 tonnes. The annulus medium is also considered when specifying the fasteners and coating to be used for the design.
Internal centralizers are required when there are concerns over the structural integrity of the inner strings and when the analysis shows risk of buckling.
Our expert view
“Internal centralizers, although appearing simple, need careful analysis during their design to make sure the units will stay in place after the pressure testing of internal strings. We pay careful consideration to the sizes to allow sufficient running clearance.”