This work studied the performance enhancement of Ubakala clay for use as drilling mud. A sample of Ubakala
clay was used for this research. The clay sample was collected, processed and beneficiated with varying
concentrations of soda ash (0-6wt %). Experiments were conducted to determine the viscosities of the control
and clay-soda ash mixture at different curing time intervals (0-8hours), temperatures (30OC-90OC) and speed of
agitation (200rpm-600rpm). Response surface methodology, with the aid of MATLAB statistical toolbox was
used to perform a statistical study and optimization of the data obtained from the study. The MATLAB curvefitting toolbox was also used to determine the rheological model that best fit the beneficiated clay and its
control. The result revealed that soda ash concentrations, temperature, curing time and their interactions terms
are significant variables in the statistical model with temperature being the most significant term, while time is
the least significant term. The rheological study of the process showed that the Bingham plastic model
appropriately described the performance of the clay samples as it gave the best fit for most of the samples
(71.67%) studied, based on the value of the adjusted R2
. The graphical representation of the control showed a
decreasing rate in viscosity within the required range of speed of agitation unlike those of the clay soda ash
mixture. Further work on Bingham model shows that an optimum predictive value of yield stress occurs for a
curing time of 8hours, temperature of 900C and soda ash concentration of 5.183wt% are the operating
parameters for enhancing the performance of Ubakala clay sample for use as a drilling mud.
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