Abstract
Improving the tribological characteristics of water-based drilling fluids by adding graphene-based lubricants has garnered attention because of the potential for a range of inorganic-material-based additives at high temperature. In this study, we constructed a green and simple adsorption approach to prepare highly dispersed graphite using a cationic surfactant for graphite modification. The findings demonstrated that the prepared graphite was highly dispersed in water and had a low sedimentation rate and small contact angle in distilled water. The concentration dosage of cetyltrimethylammonium chloride (CTAC) on graphite was 0.02 g/g. We evaluated the performance of the modified graphite as a lubricated additive in water-based drilling through a rheological study and viscosity coefficient measurement. The results showed that the viscosity coefficient of drilling fluid with 0.05% modified graphite was reduced by 67% at 180 °C. We proved that the modified graphite can significantly improve the lubrication performance of drilling fluid. Furthermore, we revealed the lubrication mechanism by analyzing the chemical structural and crystalline and morphological features of graphite through a particle size test, zeta potential test, Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD), and scanning electron microscopy (SEM) measurements. The results indicated that the modification of graphite by CTAC only occurs through physical adsorption, without changing the crystal structure. These findings provide a reference for the development of high-performance water-based drilling fluids.
Highlights
Drilling fluids are complex chemical systems that play critical roles in the petroleum industry [1,2]
We modified the surface of natural flake graphite by using a cationic surfactant cetyltrimethylammonium chloride (CTAC) for use as a lubricant in water-based drilling fluid, which can overcome the problem of natural flake graphite not evenly dispersing in drilling fluid due to its hydrophobicity
Our findings provide some guidance for future research on the lubricity of water-based drilling fluid
Summary
Drilling fluids are complex chemical systems that play critical roles in the petroleum industry [1,2]. The key feature of this material is its conductive and porous microstructure that is created because of a synergic effect between the cementitious matrix and graphite particles Another issue with water-based drilling fluids during drilling works is their relatively high friction, causing drilling engineering problems in directional, horizontal, extendedreach, cluster, and ultra-deep wells [13]. We modified the surface of natural flake graphite by using a cationic surfactant CTAC for use as a lubricant in water-based drilling fluid, which can overcome the problem of natural flake graphite not evenly dispersing in drilling fluid due to its hydrophobicity. We only used the highly dispersed modified graphite described in this paper for a performance evaluation in a simple water-based drilling fluid, and its application in complex wells has certain limitations. Our findings provide some guidance for future research on the lubricity of water-based drilling fluid
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