Optimization and Process Modeling of Viscosity of Oil Based Drilling Muds

Abstract

The viscosity of oil-based drilling mud was optimized and modeled in this study. Imported bentonite and local clay additives, and diesel oil (base fluid) were used to prepare two muds; oil-based mud with bentonite (OBMB) and oil-based mud with clay (OBMC). The local clay was beneficiated with hydrochloric acid (HCl) and then characterized using an x-ray fluorescence (XRF) spectrometer. The result of the characterization revealed that the local clay is more of silica (SiO2) which is typical of a kaolin. The interactive effects of three operating conditions, temperature, aging time, and bentonite/clay dosage, respectively, on the viscosity of each mud were determined. The Response surface methodology (RSM) of the central composite design tool of Design Expert software (version 12) was employed to optimize the viscosity of each mud. The RSM carried out revealed the interaction between the three operating variables of temperature, time, and dosage of bentonite/clay and their impact on the viscosity of each mud. Optimum viscosity of 19.3 for OBMB and 25.9 for OBMC were obtained at temperature of 313K, aging time of 30 minutes and bentonite/clay dosage of 9 wt%. Analysis of variants (ANOVA), mathematical modeling, and graphical plots further established the actual interaction between the response-viscosity of each mud and the considered process factors. The generated models revealed linear, interactive, and quadratic equations which adequately described the relationship between the viscosity of each mud and the considered factors of temperature, time, and dosage. The experimental data and the predicted results were compared, and the model predicted values are in good agreement with the experimental results. Doi: 10.28991/HEF-2021-02-04-09 Full Text: PDF

Keywords

• bentonite
• local clay
• optimization
• quadratic model
• response surface methodology
• viscosity
• rheological properties.