A Performance analysis of different types of liquid lubricants in weighted and unweighted water based drilling fluid by differential sticking tester parallel with lubricity tester

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2015
Anadut, Mehmet Uğur
Differential sticking is among the most important factor that could affect the well cost and the drilling efficiency. It occurs at the presence of overbalance pressure between mud column of the well and permeable formation. In this circumstance, the differential pressure acting on a drill string makes the drill string to stick on the well bore. Especially in directional and extended-reach wells drilling, high torque, drag and differential sticking become increasingly important issues compared to the vertical wells. Contact between steel and mud cake produce more friction especially when using water based mud compared to oil or synthetic based mud. To decrease or avoid this friction, one must add lubricants in drilling fluids In this study the performance of three different types of commercial liquid lubricants (soya based natural oil derivative, propylene glycol derivative and ethanol based liquid commercial lubricants) in weighted lignosulfonate mud, which consists barite as weighing agent and unweighted water based lignosulfonate mud were investigated. Experimental study utilized differential sticking tester, lubricity tester and API filter press to study the effectiveness of liquid lubricants. The concentrations of 2% and 3% lubricant by volume were studied and their performance was observed. According to differential sticking test result, soya based natural oil derivative lubricant has the best performance and gave 26% reduction in sticking coefficient at 2% concentration and 36% at 3% concentration compared to base mud. In addition, Propylene glycol derivative lubricant displayed 13% reduction at 2% concentration and 19% reduction at 3% concentration. Besides these, ethanol based lubricant displayed 23% reduction at 2% concentration and 33% at 3% concentration. Considering the lubricity test results, the performance of lubricants at 2% and 3% did not show a difference. An effective reduction of lubricity coefficient was observed in soya based natural oil derivative lubricant with an average reduction of 75% compared to the base mud. Propylene glycol derivative lubricant showed 30% reduction and ethanol based derivative lubricant displayed 23% reduction in lubricity coefficient compared to the base mud. Furthermore, soya based natural oil lubricant performed the lowest fluid loss and thin mud cake thickness compared to base mud and exhibited better performance compared to propylene glycol and ethanol derivative lubricants.
Citation Formats
M. U. Anadut, “A Performance analysis of different types of liquid lubricants in weighted and unweighted water based drilling fluid by differential sticking tester parallel with lubricity tester,” M.S. - Master of Science, Middle East Technical University, 2015.