Bow spring centralizer is a hunting bow shaped metal strip, which is either attached to a tool or to the outside of casing. It’s main function is to keep casing in the center of a wellbore. During cementing operations, it allows even distribution of the cement around the casing.
There are two types of bow spring centralizers.
- Welded bow spring centralizers
- Non-welded bow spring centralizers
Working of Centralizers
These are used for vertical wells. It requires both low starting forces as well as high restoring forces.
How bow spring centralizer is standardized
These bow spring centralizers undergo heat treatment in a special furnace to give bow ‘spring’ action.
The hardness of the bows is always calculated to standardize its performance.
For downhole drilling conditions, bow spring centralizer is an ideal product. As it balances the Starting Forces with the Restoring Forces to stabilize the running force.
These bows also undergo a special state of flexing before assembly for preventing snap off under extreme stress conditions.
Bow Spring Centralizers also help during running operations by reducing casing drag in the wellbore and prevent differential stroking of the casing.
They help to move filter cake from the wellbore by increasing fluid turbulence in the tool.
Both welded and non-welded Bows can be run through hole restrictions in the bore hole or smaller casing strings that are cemented in the well.