Effect of Newly Prepared Admixture on the Rheology and Early Hydration Characteristics of the Oil Well Cement Pastes

A majority of well integrity problems originate from cracks of oil well cement. To address the crack issues, bespoke sodium silicate microcapsules were used in this study for introducing autonomous crack healing ability to oil well cement under high-temperature service conditions at 80 °C. Two types of sodium silicate microcapsule, which differed in their polyurea shell properties, were first evaluated on their suitability for use under the high temperature of 80 °C in the wellbore. Both types of microcapsules showed good thermal stability and survivability during mixing. The microcapsules with a more rigid shell were chosen over microcapsule with a more rubbery shell for further tests on the self-healing efficiency since the former had much less negative effect on the oil well cement strength. It was found that oil well cement itself showed very little healing capability when cured at 80 °C, but the addition of the microcapsules significantly promoted its self-healing performance. After healing for 7 days at 80 °C, the microcapsule-containing cement pastes achieved crack depth reduction up to ~58%, sorptivity coefficient reduction up to ~76%, and flexural strength regain up to ~27%. The microstructure analysis further confirmed the stability of microcapsules and their self-healing reactions upon cracking in the high temperature oil well cement system. These results provide a promising perspective for the development of self-healing microcapsule-based oil well cements.

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Mechanical and microstructure characteristics development of hardened oil well cement pastes incorporating fly ash and silica fume at elevated temperatures

Journal of Taibah University for Science ◽

10.1080/16583655.2020.1711998 ◽

2020 ◽

Vol 14 (1) ◽

pp. 155-167 ◽

Cited By ~ 2

Author(s):

M. M. Hazem ◽

F. S. Hashem ◽

S. M. A. El-Gamal ◽

M. S. Amin

Keyword(s):

Fly Ash ◽

Silica Fume ◽

Elevated Temperatures ◽

Oil Well ◽

Cement Pastes ◽

Microstructure Characteristics ◽

Oil Well Cement ◽

Well Cement ◽

Characteristics Development

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Application of nanoparticles for strengthening wellbore cement-formation bonding

Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles ◽

10.2516/ogst/2020052 ◽

2020 ◽

Vol 75 ◽

pp. 64

Author(s):

Mtaki Thomas Maagi ◽

Gu Jun

Keyword(s):

Bond Strength ◽

Shear Bond Strength ◽

Strength Increase ◽

Oil Well ◽

Particle Sizes ◽

X Ray Diffraction ◽

Cement Pastes ◽

Optimal Replacement ◽

Oil Well Cement ◽

Well Cement

This study evaluates the wellbore shear bond strength of oil-well cement pastes containing nano-SiO2 and nano-TiO2 particles with an average of 20 ± 5 nm particle sizes. The nanoparticles were selected by weight of cement at proportions equivalent to 1, 2, 3 and 4%. The findings demonstrated that nanoparticles significantly increased the shear bond strength, and the strength increase was dependent on the nanoparticle types, dosage and curing period of the specimens. Due to effective pozzolanic activity, nano-SiO2 provided higher shear bond strength compared to nano-TiO2. The specimens containing 3% nano-SiO2 cured for 28 days displayed the utmost shear bond strength results (0.553 MPa). The optimal replacement dosage was 3% for all nanoparticles. The particle type did not affect the optimum nanoparticles replacement content. To examine the influence of nanoparticles on cement-formation bonding, a Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and thermogravimetric technique were used.

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