Intercasing
Inline Centralisers
Usage: The Intercasing Centralizers are always recommended to be run on casing liners that will be run below a drilling liner. The reason being is because the drilling liner top has historically been very difficult on slip-on (bow or solid) casing centralizers. The slip-on centralizers are either broken, stopping the liner from going in, or on flush joint casing being shoved up the liner to the liner hanger. The intercasing centralizer blades are tapered on a 30º angle that allows for a nice smooth entry into the drilling liner with no problems.
Through a window cut for a side track. The main reason for running intercasing centralizers is because of the possibility of having to pull the casing back out. Casing going down through the window is in the most relaxed position with the wellbore. Once the casing is pulled up the casing is put in much more tension especially at the window. Casing tension tries to straighten the casing which increases lateral forces. These lateral forces are subjected also to the centralizers. Slip-on centralizers can break possibly sticking the casing.
On Premium thread casing in narrow casing/wellbore annulus. The intercasing centralizer in reality is a casing pup joint with blades. This means there is no restriction from a centralizer body. These now allow standoff in the least annular space without fear of casing wedging with slip-on centralizers or having to run casing slick. If casing is run slick in close annular space there is a genuine possibility of costly cement squeezing and/or lost production. Casing run slick in a close annulus space (examples: 113/4” in 121/2”; 95/8” in 105/8”; 75/8” in 81/2”) can experience in excess of 40% no cement channeling along the casing.
Lengths In regards to costs, manufacturing time, and engineers’
preference, intercasing centralizers are manufactured and available
in a variety of lengths.
118" Intercasing: Low cost; 8" blade; No recuts; No tong area.
225" Intercasing: Approximately 30%
more cost than 18"; 15" blade length; No
tong area; Recut to same weight or lighter,
similar thread with 8" blades.
330" Intercasing: Approximately 85%
more cost than 18"; 15" blade length; Tong
area; Recut to same weight or lighter, similar
threads, no tong area.