Evaluating the Effects of Monovalent and Divalent Salts on the Rheological Properties of Water Based Mud
Ohenewaa K. Dankwa1, *, Prince Opoku Appau2, Eric Broni-Bediako1
1 Department of Petroleum Engineering, University of Mines and Technology, Tarkwa, Ghana
2 Research Institute of Enhanced Oil Recovery, China University of Petroleum Beijing, P.R. China
Drilling fluid selection plays a key role in preventing major problems encountered during drilling operations such as hole pack-off, stuck pipe and loss circulation. Mud contamination which results from the overtreatment of the mud system with additives or foreign material entering the mud system during drilling operations causes unwanted changes in the properties of the mud. This makes the mud system inefficient in performing its major roles. This research studies the effects of monovalent and divalent salts namely Potassium Chloride, Calcium Chloride, and Magnesium Chloride on the rheological properties of water-based mud system which is most vulnerable to contamination.
Sixteen mud samples were formulated of which fifteen were contaminated each with different concentrations (0.75 g, 1.50 g, 2.50 g, 3.50 g, and 5.0 g) of the various salts at ambient temperature.
The results showed that the rheological properties such as plastic viscosity, apparent viscosity and yield point of the mud samples decreased as the concentrations of various salts increase.
It was concluded that increase in the concentration of the salts resulted in a decrease in the rheological properties of the mud samples. This indicates that with the monovalent and divalent salt contamination, there is a significant decline in the performance of drilling mud since the salts affect the dispersion, hydration and flocculation behaviour of the particles. The effect was more profound with CaCl2 and MgCl2 salts than the KCl salt.
Keywords: Contaminants, Drilling fluid rheology, Monovalent and Divalent salts, Viscosity, Water based mud, Drilling fluids.
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
* Address correspondence to this authors at the Department of Petroleum Engineering, University of Mines and Technology, Tarkwa, Ghana, E-mail: odankwa@umat-edu-gh