Effect of Particle Size of Bentonite on Rheological Behavior of the Drilling Mud

摘要

Control of the particle size and concentration of particulates in mud is critical in developing a mud system that yields good well stability and prevents fluid invasion. Bentonite is an essential component of drilling fluid in water-based systems and the results of testing carried out on the drilling fluids suit the requirements of American Petroleum Institute (API) standards and Oil Companies Materials Association (OCMA, 1975) specifications. Therefore, this study deals with the investigation of the rheology of water-based mud using bentonite of different grain sizes (38, 63, 75, and 106 μm) at different concentrations (4, 5, 6, and 7.5%). Four samples of water-based mud were prepared of different grain sizes (38, 63, 75, and 106 μm) at a concentration of 4% and the rheological behavior was recorded; this was repeated at different concentrations (5, 6, and 7.5%) and the particle size distribution was demonstrated for all grain sizes. This article illustrates that the components of flow, plastic viscosity, and yield point are absolute flow properties. They reflect the colloidal and surface-active behavior of solids present in drilling fluids. Both properties affect the apparent viscosity as measured by a Fann VG meter (Fann, Houston, TX).