Rheological Properties of Bentonite/Polymer Based Drilling Fluid Under Different pH Conditions

Abstract

To success the drilling operations, different criteria must be taken in account. One of the most important criterion is the design and performance of drilling fluids, which is greatly related to their rheological properties. Furthermore, it is crucial to study the rheological behavior of water-based drilling fluid based on bentonite/polymer. The current study aims at addressing the influence of pH on the rheological properties of bentonite/polymer based drilling fluid, furthermore, recommending the best range of pH, which provides high performance and safety of this drilling fluid. The obtained results showed that shear stress increased when increasing pH. It can be also noticed that the plastic viscosity (PV) and yield point (YP) of the drilling fluid 1 (F1) increased in high pH region and decreased in the other pH region. The plastic viscosity of the drilling fluid 2 (F2) is not significant. The higher value of YP/PV is located at a pH of 8.44, and this ratio decreases when increasing pH. These findings proved that keeping pH superior to 7 and inferior to 12 resulted in good rheological properties of drilling fluids that will help to remove the rock cuttings from the borehole to surface, and minimize the total cost of the drilling operations.