An improvement to physical properties of heavy-weight oil well cements using carbon nanotubes

Abstract

This study experimentally investigates the effect of multi-walled carbon nanotubes (MWNT’s), as a reinforcing material, on the physical properties of heavy-weight oil well cements. A candidate well is selected and the properties of the cement slurry used in a problematic section of the well are tested in the laboratory. Carbon nanotubes (CNT’s) are added as fibers to the cement slurry and the improvements in the cement slurry and stone properties are studied. This work discusses the problems associated with conventional heavy-weight oil well cement used in the candidate well and reports the detail of the improvements on cement properties obtained by adding CNT’s to cement slurry formulation. These properties include cement slurry rheological properties, free water, fluid loss, thickening time, cement stone elasticity, and compressive strength. When only 1 wt.% of CNT is added to the cement slurry, the yield point and plastic viscosity increase by eight and five times respectively, while the free water and fluid loss of cement slurry are reduced by 85% and 70% respectively. In addition, cement stone compressive strength increases by 73.8%. Moreover, the elastic properties of the cement stone are improved and higher values for the Young's modulus and Poisson's ratio are achieved; however, there is an optimum concentration of nano-additive at which the maximum yield point, plastic viscosity, compressive strength, Young's modulus, and Poisson's ratio are reached. The results of this study can be used to optimize the cement slurry design in any given set of conditions.