US 2014/0174192 A1 · APPARATUS FOR MEASURING SHEAR BOND STRENGTH OF SET CEMENT AND METHOD OF USING SAME

Abstract

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.

Claims36

Dependent claims

An apparatus for testing shear bond strength of a set cement comprising:

(a) a circular housing;
(b) a vertical rod of a length sufficient to extend through the uppermost portion of the housing and through the lowermost portion of the housing;
(c) a solid base plate for positioning onto the bottom of the housing, the solid base plate having on its inner face a recessed area for securing the lowermost portion of the vertical rod;
and
(d) a test plate for positioning onto the housing having a through-hole for the vertical rod, one surface of the test plate being flat and the other surface having a recessed cavity surrounding the through-hole.

2 more elements

A method of pre-determining the shear bond strength of a cement mix prior to pumping a cementitious slurry containing the cement mix between a pre-selected subterranean formation penetrated by a wellbore and casing within the wellbore, the method comprising:

(a) introducing a portion of the cementitious slurry into a testing apparatus, the testing apparatus comprising:
(i) a circular housing;
(ii) a base plate having a recessed area;
(iii) a vertical rod which extends from the recessed area of the support base past the uppermost portion of the circular housing
wherein a sample core of the pre-selected subterranean formation is placed between the inner wall of the circular housing and the vertical rod, the cementitious slurry being introduced into the testing apparatus between the sample core and the vertical rod;
(b) positioning a test plate onto the top of the circular housing, the test plate having an opening through which the uppermost portion of the vertical rod extends;
(c) subjecting the testing apparatus to heat at a temperature and for a time sufficient for the cementitious slurry to harden in the testing apparatus;
(d) removing the test plate and the base plate from the circular housing;
(e) applying a flat surface testing plate having a through-hole onto the bottom of the housing, the bottom of the vertical rod extending through the through-hole of the flat surface testing plate;
(f) applying pressure onto the top of the vertical rod;
(g) measuring the maximum force required to break the bond between the hardened cement and the vertical rod;
and
(h) determining the shear bond strength between the vertical rod and the hardened cement by dividing the maximum force by the area of the vertical rod in contact with the hardened cement
wherein the shear bond strength of step (h) approximates the shear bond of the cement mix, when hardened, between the subterranean formation and the casing within the wellbore.

11 more elements

A method of measuring shear bond strength of a cement to be set in a wellbore penetrating a subterranean formation, the method comprising:

(a) introducing into a circular housing a cementitious slurry wherein:
(i) a solid base plate is secured to the bottom of the housing;
(ii) a vertical rod extends from the bottom of a recessed area of the inner surface of the base plate to the top of the housing;
and
(iii) a sample core of the subterranean formation is within the circular housing, the outer wall of the sample core being adjacent to the inner wall of the housing and wherein the bottom of the sample core is adjacent to the base plate
wherein the cementitious slurry is introduced into the housing between and the sample core;
the vertical rod
(b) forming a testing apparatus by positioning a test plate onto the top of the circular housing, the test plate having a flat surface and a through-hole and wherein the upper portion of the vertical rod extends through the through-hole;
(c) subjecting the testing apparatus to heat at a temperature and for a time sufficient for the cementitious slurry to set in the testing apparatus;
(d) removing the test plate and the base plate from the circular housing;
(e) applying a testing plate onto the bottom of the housing, the testing plate having a through-hole for passing the bottom of the vertical rod through the through-hole and further wherein the testing plate has a cavity surrounding the through-hole, the sample core resting within the cavity;
(f) applying a push rod over the top of the vertical rod, applying pressure onto the push rod and measuring the maximum force required to break the bond between the set cement and the sample core;
and
(g) determining the shear bond strength between the set cement and the sample core by dividing the maximum force by the surface area of the vertical rod in contact with the set cement.

11 more elements

(a) introducing a portion of the cementitious slurry into a testing apparatus, the testing apparatus comprising:
(i) a circular housing;
(ii) a base plate having a recessed area;
(iii) a vertical rod which extends from the recessed area of the base plate past the uppermost portion of the circular housing
wherein a sample core of the pre-selected subterranean formation is placed between the inner wall of the circular housing and the vertical rod, the cementitious slurry being introduced into the testing apparatus between the sample core and the vertical rod;
(b) forming a testing apparatus by positioning a test plate onto the top of the circular housing, the test plate having an opening through which the uppermost portion of the vertical rod extends;
(c) subjecting the testing apparatus to heat at a temperature and for a time sufficient for the cementitious slurry to harden in the testing apparatus;
(d) removing the test plate and the base plate from the circular housing;
(e) applying a testing plate onto the bottom of the housing, the testing plate having a through-hole for passing the bottom of the vertical rod through the through-hole and further wherein the testing plate has a cavity surrounding the through-hole, the sample core resting within the cavity;
(f) applying a push rod over the top of the vertical rod, applying pressure onto the push rod and measuring the maximum force required to break the bond between the set cement and the sample core;
and
(g) determining the shear bond strength between the hardened cement and the sample core by dividing the maximum force by the surface area of the vertical rod in contact with the hardened cement
wherein the shear bond strength of step (g) approximates the shear bond strength of the cement mix, when hardened, between the subterranean formation and the hardened cement.

10 more elements

Dependencies are inferred from the claim text.

Apparatus for measuring shear bond strength of set cement and method of using same

Life of this patent

Apparatus for measuring shear bond strength of set cement and method of using same

Life of this patent

Abstract

Claims36