Permeability and elastic properties assessment of alumina nanofiber (ANF) cementitious composites under simulated wellbore cyclic pressure

Highly dispersed Alumina Nanofibers (ANF's) were utilized in oil well cement class “H” to investigate effects of ANF's on the cement's mechanical and microstructural properties under simulated wellbore conditions. Cement composites consisted of a reference (Ref) sample containing no ANF's and three additional formulations with 0.1%, 0.2%, and 0.3% ANF's by weight of cement (BWOC) incorporated in cement formulations with various common additives. The provided producing liquid dispersion methodology was assessed using a Transmission Electron Microscope (TEM) with each composite formulation undergoing permeability and elastic property testing under simulated cyclic confining wellbore pressures. The compressive strength was also measured along with a microstructural assessment. The microstructural assessment consisted of measuring the formation of hydration products using an X-ray diffractogram (XRD) and thermogravimetric analyzer (TGA). The results indicate that 0.1% of ANF provides the greatest increase in mechanical properties and possesses the lowest permeability through all pressure cycles. Additionally, the amount of Calcium Silicate Hydrate (C-S-H) and Degree of Hydration (DOH) was maximized for 0.1% ANF compared to other composite formulations.