Economical Cost Effect of Rheological Properties of Local Clay to Imported Bentonite

Rheological properties of local clays obtained from Aviara and Uzere of Delta State Nigeria, compared to imported Bentonite clay, the industry standard for drilling mud formulation. The research aims to evaluate the suitability of local clay rheology as a cost-effective alternative to Bentonite in drilling operations. Laboratory analyses were conducted to determine Local clay rheological properties —apparent viscosity, plastic viscosity, and yield point – measurable to API standards. Each sample, dial readings were recorded at 600 RPM and 300 RPM which was used to calculate key rheological parameters: Apparent Viscosity (AV) – an indicator of the overall viscosity of the mud under flowing conditions: AV = 600 RPM reading. Plastic Viscosity (PV) – a measure of the mud’s resistance to flow due to internal mechanical friction between solid particles: PV = 600 RPM reading – 300 RPM reading. Yield Point (YP) – the measure of the mud’s ability to lift and suspend drilled cuttings under static conditions: YP = 300 RPM reading – PV. These parameters provided insight into two critical aspects of mud performance: 1. PV reflects the internal friction and solids concentration. 2. YP reflects the electrochemical attractive forces between particles, which directly influence cuttings-carrying capacity. Gel strength was also determined to assess the behavior of the mud—the ability to develop a gel structure when static and to break down upon agitation. For this, the mud sample was allowed to stand undisturbed in the viscometer for 10 seconds and 10 minutes. After each rest period, the viscometer rotor was turned at 3 RPM, and the maximum dial reading before gel breakage was recorded as the initial gel strength (10 seconds) and 10-minute gel strength, respectively. This entire rheological evaluation procedure was repeated for both the local clay-based muds and the bentonite-based muds, enabling a direct comparison of their flow characteristics, cuttings transport potential, and gelation behavior under standardized laboratory conditions. Results showed that Bentonite exhibited superior apparent viscosity, plastic viscosity and yield point confirming its established performance in drilling applications. However, the local clays demonstrated moderate apparent viscosity, plastic viscosity and yield point ratios, as potential for drilling mud. Limitation observed is lesser inherent capacity compared to imported Bentonite which can be mitigated through substantial chemical treatment to enhance adequate suspension of drill cuttings and hole cleaning to serve as partial or full substitutes for Bentonite, thereby lowering operational costs and reducing reliance on imported bentonite.