Effect of Barite Concentrations on Oil Based Drilling Mud Density and Rheology

Abstract

Drilling fluid is an essential element to the drilling process as most drilling challenges can be traced to the condition of the drilling mud used. Density and rheology are among the basic properties of drilling fluid usually defined by a well program and closely monitored during drilling operation. The sustainability of the density of drilling fluid is a key factor that needs deliberate monitoring to ensure that its density is higher than the formation density, so as to avert unexpected complications. Hence this research was aimed at investigating the effect of barite concentration on oil base drilling fluid density and rheology. Formulations and testing procedures were conducted in accordance with American Petroleum Institute (API) specifications. Experimental results showed that the increase of drilling mud is a direct function of increase in concentration of barite. It was also observed that when the barite concentration was 0%, the plastic viscosity decreased as the temperature increased meaning that the drilling mud sagged whereas an increase in barite concentration to 10% revealed an opposite relationship, the plastic viscosity increased as the temperature increased. The yield point at 0% barite concentration gave the least yield point; this signifies that the barite concentration aids in the carrying capacity of the drilling mud. It was also observed that the barite concentration can be used to make the fluid more pseudo-plastic in nature. The consistency index (K) increases as the barite concentration is increased, which indicated that the fluid becomes more viscous when barite concentration is increased. Therefore, results have showed that concentration of barite affect the density of drilling mud as well as rheological properties.