The Use of Graphite to Improve the Stability of Saudi Class G Oil-Well Cement against the Carbonation Process

Abstract

Oil-well cement physical characteristics considerably change after being carbonated by a CO2-rich solution. In this study, the influence of graphite particles in the characteristics of oil-well cement reacted with a CO2-rich solution at 130 °C and 10 MPa for 10 days was studied. After 10 days of carbonation, incorporating 0.2% by weight of cement (BWOC) of graphite into the cement slurry decreased the carbonation depth by 29.8% as confirmed by the direct measurement and the micro-computerized tomography scan technique. The addition of 0.2% BWOC of graphite also reduced the cement matrix permeability by 31.4% and increased its compressive strength by 16.4% and tensile strength by 23.8% compared to the sample without graphite. The decrease in the cement matrix portlandite concentration and permeability of the samples prepared with graphite contributed to promote the cement matrix carbonation resistance. The microscopic images also proved that the incorporation of graphite delayed the leaching of calcium carbonate, and this is also attributed to decreasing the cement strength deterioration.

Effect of Graphite on the Mechanical and Petrophysical Properties of Class G Oil Well Cement

“…The slurries are different in graphite content, where the base slurry (the first formulation) has no graphite, and the graphite-based slurry (the second formulation) is prepared with 0.2 %BWOC graphite. The graphite content considered for the second formulation was based on the recommendation of Mahmoud et al 23 The particle size distributions for Saudi Class G cement and graphite powder are shown in Figure 1. The D 50 for Class G cement is 21.3 μm, while for graphite is 41.6 μm.…”

“…The slurries are different in graphite content, where the base slurry (the first formulation) has no graphite, and the graphite-based slurry (the second formulation) is prepared with 0.2 %BWOC graphite. The graphite content considered for the second formulation was based on the recommendation of Mahmoud et al…”

“…Cai et al 22 found that the addition of graphite improved the strength and deformation resistance of the common Class G cement. Mahmoud et al 23 showed that the addition of the graphite could improve the carbonation resistance of Class G cement in CO 2 saturated environment.…”

Properties and Performance of Oil Well Slurry and Cement Sheath Incorporating Nano Silica: A Review

“…Chemical reactions are the most common cause of changes in the macroscopic characteristics of cement materials. 88 Chemical reactions in cementing materials, on the other hand, may be acceptable if they do not reduce the mechanical strength of the cement sheath or increase its hydraulic conductivity.…”

Investigation and Optimisation of the Rheological Properties of Magnesium Potassium Phosphate Cement with Response Surface Methodology

“…Magnesium phosphate cement (MPC), also known as chemically bonded phosphate ceramic, is an alternative clinker-free binder which has attracted increasing attention worldwide [ 1 , 2 , 3 , 4 , 5 ]. Compared to the traditional cement [ 6 ], MPC possesses many superior properties, such as super-fast setting, high early strength, strong bonding, low drying shrinkage and better durability [ 1 , 2 , 3 , 4 , 5 ]. These properties make MPC remarkably popular in the fast repair, strengthening and rehabilitation of concrete infrastructures such as pavements, highways and airport runways [ 7 , 8 ].…”