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ARS Home » Plains Area » El Reno, Oklahoma » Oklahoma and Central Plains Agricultural Research Center » Agroclimate and Hydraulics Research Unit » Research » Publications at this Location » Publication #393234

Research Project: Development of a Monitoring Network, Engineering Tools, and Guidelines for the Design, Analysis, and Rehabilitation of Embankment Dams, Hydraulic Structures, and Channels

Location: Agroclimate and Hydraulics Research Unit

Title: Experimental analysis of Wellbore cement-steel bond mechanics and characterization

item Wise, Jarrett
item AL DUSHAISHI, MOHAMMED - Oklahoma State University
item BOCANEGRA-YANEZ, JOSE - Oklahoma State University
item LEE, HUNJOO - Oklahoma State University
item Hunt, Sherry

Submitted to: Geoenergy Science and Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2023
Publication Date: 3/21/2023
Citation: Wise, J.L., Al Dushaishi, M., Bocanegra-Yanez, J., Lee, H., Hunt, S. 2023. Experimental analysis of Wellbore cement-steel bond mechanics and characterization. Geoenergy Science and Engineering. 225. Article 211709.

Interpretive Summary: Cement is used in everything from general construction to fluid barriers. Debonding of cement to steel is not well understood. Previous research only focuses on measuring the bond strength. Theoretical models show that debonding is more complex and two other parameters (critical energy and contact stiffness) are critical in the analysis of bonds. A new experimental method was developed which measured all three parameters and tested them with different strain rates. The results showed that slow strain rates cause relaxation of the bond during failure compared to the faster strain rates. From testing over 120 samples, specific values for the bond strength, critical energy, and contact stiffness were determined. These results can be used in integrity models to more accurately predict the failure of cement to steel debonding.

Technical Abstract: Portland cement is commonly used in everything from general construction to fluid barriers in environmental and petroleum structures. Finite element models have shown that the bond strength between cement to steel is a weak point in integrity analyses, but the failure mechanism is not well understood. Bond strength of cement to steel has been modeled using Traction Separation Law which includes the bond strength, critical energy, and contact stiffness associated with the bond. However, experimental measurements only focus on the bond strength, resulting in an incomplete analysis of the failure. A novel experimental methodology was developed to measure the tensile bond strength, critical energy, and contact stiffness of neat cement to steel bonds cured at atmosopheric conditions for two days. Strain rates of 0.1 mm/min, 1.0 mm/min, and 10 mm/min were tested. The results showed that the 0.1 mm/min strain rate is too slow for bond testing since two of the bonding parameters experienced relaxation during testing and resulted in low values which contradicts the ASTM bond testing standard (ASTM D2936-20). The 1.0 and 10 mm/min strain rates do not have stastical significance with respect to the bonding parameters. From the direct tensile tests of neat cement to steel, the bond strength is 0.61 MPa, the critical energy is 204.2 J/m^2, and the contact stiffness is 1.00E+09 N/m^3.