Method of analyzing the bond strength of cement and formation with discrete image analysis

A method of assessing the bond strength of cement, the method comprising:

• casting a cement on top of a formation sample;
• curing the cement to create a composite plug, wherein:
• the composite plug comprises a formation layer, a cement layer, and an interface region between the formation layer and the cement layer, and
• the cement extends into the formation sample in the interface region;
• imaging the composite plug to gather a series of discrete images from a first point to a second point, wherein:
• each discrete image in the series of discrete images depicts a unique horizontal cross section of the composite plug bounded by an outer perimeter of the composite plug;
• and
• the interface region is disposed between the first point and the second point;
• analyzing each discrete image in the series of discrete images to determine a porosity measurement of each discrete image and determine a depth of the interface region from the porosity measurement of each discrete image;
• and
• assessing the bond strength between the cement layer and the formation layer based on the depth of the interface region and a formula:
• σ α N, wherein σ denotes the bond strength and N denotes a number of discrete images within the interface region.

A method of analyzing a composite plug, the method comprising:

• casting a cement on top of a formation sample;
• curing the cement to create a composite plug, wherein:
• the composite plug comprises a formation layer, a cement layer, and an interface region between the formation layer and the cement layer, and
• the cement extends into the formation sample in the interface region;
• non-destructively imaging the composite plug with an X-ray Computed Tomography scan to gather a series of discrete images from a first point to a second point, wherein:
• each discrete image in the series of discrete images depicts a cross section of the composite plug;
• the discrete images in the series of discrete images are taken at set increments throughout a depth of the composite plug;
• and
• the interface region is disposed between the first point and the second point;
• analyzing each discrete image in the series of discrete images to determine a porosity measurement of each discrete image and determine a depth of the interface region by a number of discrete images between a first boundary of the interface region and a second boundary of the interface region, wherein:
• the first boundary of the interface region is the boundary between the interface region and the cement layer;
• and
• the second boundary of the interface region is the boundary between the interface region and the formation layer;
• and
• assessing the bond strength between the cement layer and the formation layer with a formula:
• σ α N, wherein:
• σ denotes the bond strength;
• and
• N denotes the number of discrete images within the interface region.