Corrosion-resistant Foamed Cements for Carbon Steels
The cementitious material consisting of Secar #80, Class F fly ash, and sodium silicate designed as an alternative thermal-shock resistant cement for the Enhanced Geothermal System (EGS) wells was treated with cocamidopropyl dimethylamine oxide-based compound as foaming agent (FA) to prepare numerous air bubble-dispersed low density cement slurries of and #61603;1.3 g/cm3. Then, the foamed slurry was modified with acrylic emulsion (AE) as corrosion inhibitor. We detailed the positive effects of the acrylic polymer (AP) in this emulsion on the five different properties of the foamed cement: 1) The hydrothermal stability of the AP in 200 and #61616;C-autoclaved cements; 2) the hydrolysis-hydration reactions of the slurry at 85 and #61616;C; 3) the composition of crystalline phases assembled and the microstructure developed in autoclaved cements; 4) the mechanical behaviors of the autoclaved cements; and, 5) the corrosion mitigation of carbon steel (CS) by the polymer. For the first property, the hydrothermal-catalyzed acid-base interactions between the AP and cement resulted in Ca-or Na-complexed carboxylate derivatives, which led to the improvement of thermal stability of the AP. This interaction also stimulated the cement hydration reactions, enhancing the total heat evolved during cement’s curing. Addition of AP did not alter any of the crystalline phase compositions responsible for the strength of the cement. Furthermore, the AP-modified cement developed the porous microstructure with numerous defect-free cavities of disconnected voids. These effects together contributed to the improvement of compressive-strength and –toughness of the cured cement. AP modification of the cement also offered an improved protection of CS against brine-caused corrosion. There were three major factors governing the corrosion protection: 1) Reducing the extents of infiltration and transportation of corrosive electrolytes through the cement layer deposited on the underlying CS surfaces; 2) inhibiting the cathodic reactions at the corrosion site of CS; 3) extending the coverage of cement over CS surfaces; and, 4) improving the adherence of the cement to CS surfaces. Thus, the CS’s corrosion rate of 176 milli inch/per year (mpy) for 1 wt% FA-foamed cement without AP was considerably reduced to 69 mpy by adding only 2 wt% AP. Addition of AP at 10 wt% further reduced this rate to less than 10 mpy.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE EE OFFICE OF ENERGY EFFICIENCY & RENEWABLE ENERGY (EERE)
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1091766
- Report Number(s):
- BNL-101088-2012-IR; R&D Project: 10314; EB4005020
- Country of Publication:
- United States
- Language:
- English
Similar Records
HYDROTHERMALLY SELF-ADVANCING HYBRID COATINGS FOR MITIGATING CORROSION OF CARBON STEEL.
Lightweight CO{sub 2}-resistant cements for geothermal well completions