Effects of Cissus Populnea on the Rheological Properties of Local Clay

Globally, Wyoming bentonite has been observed as the only accepted drilling fluid. Hence, the importance of investigating the mode by which Cissus populnea affects the rheological properties of local clay and as possible substitute for the international standard clay as drilling fluid. Ten samples of the local mud were taken at different locations of Afuze deposit, the stem bark of Cissus populnea was purchased in Ekiti State and authenticated at the herbarium, University of Ibadan, Nigeria. Its extraction was effected using the soxhlet extractor apparatus. Samples A and C, were respectively the mud of the local clay and a mixture of the Cissus populnea extract and the local clay. A control sample, B was formed from a mixture of water and the International Standard Wyoming bentonite which was obtained from the Petroleum Engineering Department of the University of Ibadan. Rheological properties of each of the samples were determined. The results of sample C (density (9.85 lb/gal), pH (9.9–11.3); funnel viscosity (50–62 seconds); hydroxylethyl cellulose at 600 rpm (22-38 cp); filtrate value (13.0–15.8 ml); sand content (0.50–0.81ppg); gel strength (15-21 lb/100ft2) and yield stress (7-13 lb/100ft2)) fell within the API RP–13B standard for drilling fluid. The analysis showed that the differences between samples A, B and C were negligible and that the local clay treated with Cissus populnea can serve as a substitute for foreign clay. KEYWORDS: bentonite, Cissus Populnea, local clay, mud weight, rheological properties

IDENTIFICATION OF CLAY SOIL MINERALOGY AND SWELLING BY THE FREE SWELL RATIO METHOD

The paper presents the results of free swell measurements of Neogene clays and model clay mixtures composed of Wyoming bentonite and Sedlec kaolinite. Modified free swell index (MFSI) as well as free swell ratio (FSR) were determined and analyzed with respect to pore fluid chemistry, mineral composition and clay content. The FSR, defined as the ratio of the equilibrium sediment volume of 10-g oven dried soil in 0.0025% NaCl solution to that in kerosene, has proved to provide only a rough prediction of clay mineralogy in natural soils.