Method of measuring shear bond strength of cement

摘要

An apparatus for determining shear bond strength of a cement to be set within a wellbore penetrating a subterranean formation consists of a housing, a vertical rod which extends from the uppermost portion of the housing through the lowermost portion of the housing, a base plate for positioning onto the bottom of the housing and for supporting the lowermost portion of the vertical rod, and a test plate for positioning onto the top of the housing through which the uppermost portion of the vertical rod extends. The apparatus may further contain a push rod. Shear bond strength is determined by introducing into the housing a sample core of the formation prior to introduction of a slurry containing the cement. The force required to break the bond between the vertical rod and the set cement may be used to determine the shear strength between the casing within the wellbore and the set cement when the cement is hardened within the wellbore. The force required to break the bond between the set cement and the sample core may be used to determine the shear strength between the set cement and formation core when the cement is hardened within the wellbore.

主权项

1. A method of measuring shear bond strength of a cement to be set in a wellbore penetrating a subterranean formation comprising:
(a) introducing into a housing a cementitious slurry containing a cement mix, wherein:
(i) a base plate is secured to the bottom of the housing;(ii) a vertical rod extends from the bottom of a recessed area of the base plate to the top of the housing; and(iii) a sample core of the subterranean formation is within a circular housing, wherein an outer wall of the sample core is adjacent to an inner wall of the housing and wherein a bottom of the sample core is adjacent to the base platewherein the cementitious slurry is introduced into the housing between the vertical rod and the sample core and further wherein a portion of the cementitious slurry travels between the outer wall of the core and the inner wall of the housing;
(b) positioning a test plate onto a top of a housing, wherein the flat surface of the test plate faces the cementitious slurry within the housing; (c) subjecting the apparatus to heat at a temperature and for a time sufficient for the cementitious slurry to set; (d) removing the base plate from the bottom of the housing and removing the test plate from the top of the housing; (e) positioning the test plate onto the bottom of the housing wherein the flat surface of the test place faces the set cement; (f) applying pressure onto the top of the vertical rod; (g) measuring the maximum force required to break the bond between the set cement and the vertical rod; and (h) determining the shear bond strength between the vertical rod and the set cement by dividing the maximum force by the surface area of the vertical rod in contact with the set cement.