Based on the method of mud cake to agglomerated cake (MTA), the synergism of mud cake modifier (MCM)
with forming agent of agglomerated cake (FAAC) in oil and gas well is studied by means of X-ray diffraction (XRD), environmental
scanning electron microscopy (ESEM) and atomic absorption spectroscopy (AAS). The results show that the
mud cake with MCM at cement-formation interface (CFI) is corroded by FAAC. And the corrosion spots and cracks are
formed. The glassy substance in mud cake is depolymerized by hydrated ions from oilwell cement slurry through these
spots and cracks. The soluble ionic groups in mud cake form. The diagenesis in mud cake at CFI occurs. The calcium silicate
hydrates (CSH), ettringite, film zeolite, rod zeolite and natrolite gels in mud cake generate. Ultimately, it achieves the
integrated solidification and cementation (ISC) among cement paste, agglomerated cake and formation at CFI. This paper
explains why the isolation quality of CFI is improved by the MTA method.
This experimental investigation focused on the mechanical and damping properties of raw and alkali treated flax fibers reinforced cementitious composites. The objective of this study was to research the influence of flax fiber for the damping properties of cementitious composites. The mechanical strengths were obtained using compressive and flexural tests and damping properties were measured using a dynamic mechanical analysis. Structural modifications to the treated flax fibers were analyzed using scanning electronic microscopy and mercury intrusion porosimetry. Results showed that cement compressive strength was decreased, and flexural strength was increased by the addition of untreated flax fibers. Alkali treatment improved the mechanical strength of flax reinforced cement. The addition of flax fibers improved cement damping properties, and the damping effect of untreated flax fibers was greater than that of alkali treated fibers. The loss tangent of the cementitious composites reinforced with raw and alkali treated flax fibers at an amount of 1 wt % of cement was improved by 45.83% and 37.5% at 20 Hz, respectively. The damping properties of flax fiber was attributed to friction between elementary fibers and between adjacent fiber cell walls and slipping between the fiber and matrix. Callouses, pectin, and lignocellulose in untreated flax fiber contributed to damping and their removal by alkali treatment was the main reason why untreated flax fibers had a greater damping effect as compared to alkali-modified flax fibers.
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