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Title: Effect of MgO Additive on Volumetric Expansion of Self-Degradable Cements

Abstract

We identified hard-burned magnesium oxide (MgO) as a suitable expansive additive for improving the plugging performance of self-degradable, temporary sodium silicate-activated slag/Class C fly ash (SSASC) blend cement sealers into rock fractures in Enhanced Geothermal Systems (EGSs). MgO extended the volumetric expansion of sealers during their exposure to a hydrothermal environment at 200 C under pressures, ranging from 300 to 1500 psi. A great expansion ratc of 19.3% was observed by adding 3.0 wt% MgO under 300 psi pressure, thus promising to plug thoroughly inner fracture. When the pressure was increased from 300 psi to 1500 psi, the expansion rate of cement markedly reduced, corresponding to the formaLion of crack-free specimens and the improvement of compressive strength. However, with 3.0 wt% MgO, the specimens still engendered the generation of numerous visual cracks, although they were prepared under a high pressure of 1500 psi. The effective content of MgO in minimizing and eliminating the generation of cracks was 2.0 wt%, which provided a moderate expansion of {ge} 0.5%. The compressive strength of 2.0 wt% MgO specimens made under a pressure of 300 psi rose {approx} 1.7-fold to 4816 psi with an increasing pressure to 1500 psi. The in-situ growth of brucitemore » crystal formed by the hydrothermal hydration of MgO was responsive for such an expansion of the SSASC cement; meanwhile. two crystalline hydrothermal reaction products, 1.1 nm tobermorite and calcium silicate hydrated, contributed to the development of the sealer's compressive strength. Thus, the increasing pressure seems to suppress and control a growth rate of brucite crystal in response to a lower extension of expansion. Furthermore, all MgO-conlaining SSASC sealers possessed the water-catalyzed self-degradable properties.« less

Authors:
; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE EE OFFICE OF ENERGY EFFICIENCY & RENEWABLE ENERGY (EERE)
OSTI Identifier:
1049212
Report Number(s):
BNL-96339-2011-IR
EB4005020; TRN: US201218%%188
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; ADDITIVES; CALCIUM SILICATES; CEMENTS; FLY ASH; FRACTURES; GEOTHERMAL SYSTEMS; HYDRATION; MAGNESIUM OXIDES; PERFORMANCE; PLUGGING; SODIUM

Citation Formats

Sugama, T, Warren, J, and Butcher, T. Effect of MgO Additive on Volumetric Expansion of Self-Degradable Cements. United States: N. p., 2011. Web. doi:10.2172/1049212.
Sugama, T, Warren, J, & Butcher, T. Effect of MgO Additive on Volumetric Expansion of Self-Degradable Cements. United States. https://doi.org/10.2172/1049212
Sugama, T, Warren, J, and Butcher, T. 2011. "Effect of MgO Additive on Volumetric Expansion of Self-Degradable Cements". United States. https://doi.org/10.2172/1049212. https://www.osti.gov/servlets/purl/1049212.
@article{osti_1049212,
title = {Effect of MgO Additive on Volumetric Expansion of Self-Degradable Cements},
author = {Sugama, T and Warren, J and Butcher, T},
abstractNote = {We identified hard-burned magnesium oxide (MgO) as a suitable expansive additive for improving the plugging performance of self-degradable, temporary sodium silicate-activated slag/Class C fly ash (SSASC) blend cement sealers into rock fractures in Enhanced Geothermal Systems (EGSs). MgO extended the volumetric expansion of sealers during their exposure to a hydrothermal environment at 200 C under pressures, ranging from 300 to 1500 psi. A great expansion ratc of 19.3% was observed by adding 3.0 wt% MgO under 300 psi pressure, thus promising to plug thoroughly inner fracture. When the pressure was increased from 300 psi to 1500 psi, the expansion rate of cement markedly reduced, corresponding to the formaLion of crack-free specimens and the improvement of compressive strength. However, with 3.0 wt% MgO, the specimens still engendered the generation of numerous visual cracks, although they were prepared under a high pressure of 1500 psi. The effective content of MgO in minimizing and eliminating the generation of cracks was 2.0 wt%, which provided a moderate expansion of {ge} 0.5%. The compressive strength of 2.0 wt% MgO specimens made under a pressure of 300 psi rose {approx} 1.7-fold to 4816 psi with an increasing pressure to 1500 psi. The in-situ growth of brucite crystal formed by the hydrothermal hydration of MgO was responsive for such an expansion of the SSASC cement; meanwhile. two crystalline hydrothermal reaction products, 1.1 nm tobermorite and calcium silicate hydrated, contributed to the development of the sealer's compressive strength. Thus, the increasing pressure seems to suppress and control a growth rate of brucite crystal in response to a lower extension of expansion. Furthermore, all MgO-conlaining SSASC sealers possessed the water-catalyzed self-degradable properties.},
doi = {10.2172/1049212},
url = {https://www.osti.gov/biblio/1049212}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Sep 30 00:00:00 EDT 2011},
month = {Fri Sep 30 00:00:00 EDT 2011}
}