Study of the Rheological Properties of Various Oil-Based Drilling Fluids

The rheology study of drilling fluid is important to understand the performance of drilling fluid to efficiently remove, transport and suspend cuttings, to maintain a stable wellbore and minimize mud pump requirements. Drilling fluid rheology is often maintained at required rheology standards through the use of additives or dilution depending on the needs of the operation. In this project, a rheology modifier named VisPlus is added into the drilling fluid to improve drilling fluid rheology. The objectives of this project is to study the rheology of invert emulsion drilling fluid or invert oil drilling fluid, which is a type of oil-based drilling fluid (OBM) using different concentrations of the rheology modifier, VisPlus. The rheology of drilling fluid with different concentrations of VisPlus were analyzed and compared against rheological requirements. This rheology study also includes the correlation of the experimental results against three rheological models namely Herschel-Bulkley, Casson and Power Law. From the correlation results, the most rheological model to predict drilling fluid rheology is identified. Experiments were conducted at oilfield units, which is convertible to SI unit. It was observed that the optimum concentration for VisPlus is 3 pounds-per-barrel (ppb), equivalent to 8.58 kilogram per cubic meter of drilling fluid. From the correlation results, the most accurate rheological model to represent drilling fluid rheology is the Herschel-Bulkley Rheological model.