DEVICE FOR TWO-STAGE CEMENTING OF CASING STRINGS Russian patent published in 1996 - IPC

FIELD: well drilling. SUBSTANCE: device for two-stage cementing of casing strings has body with filling holes and splines on internal surface in the upper part. Arranged in body is shear bushing which overlaps filling holes. Device has carrying column provided with splines in its lower part which are mated with body splines. Device has additional shear bushing with thrust ring and splines on lower end face. Shear bushing is located in the lower part of carrying column and connected with the latter by means of shear members. Shear bushing upper part has splines to mate the splines of the lower end face of additional shear bushing. EFFECT: increased reinforcing of well due to provision of tensioning of string upper stage. 1 dwg