SEDIMENTOLOGY AND RESERVOIR QUALITY OF OUTCROPPING SEDIMENTS IN LOKOJA AND ENVIRONS, SOUTHERN BIDA BASIN
ABSTRACT
Field studies were carried out on outcropping sediments exposed in Lokoja and its environs to gain insight into reservoir characteristics and sedimentological characteristics. Sieve analysis and petrographic analysis were carried out on fresh samples of the sediments to determine their statistical parameters, paleodepositinal environment and their reservoir quality. Granulometric analysis of the Filele sands reveals that the sediments are medium to coarse, moderate to poorly sorted, near symmetrical to positively skewed and mainly leptokurtic, While the granulometric analysis of the Mount Patti sands reveals that the sediments are fine to medium, well sorted to moderate sorting, negatively skewed to positively skewed and mesokurtic to leptokurtic. The petrographic analysis of the Filele sands reveals that the sediments consist averagely of 78% Quartz, 17% Feldspar, and 5% Rock fragment, while the Mount Patti sands consist of 90% Quartz, 6% Feldspar, and 4% Rock Fragment. Ternary diagram also reveals that the sediments are mainly sub-arkose. The average mineralogical maturity index (IMM) for the Filele sands is 3.8 indicative of sub-maturity, while the Patti sands with 11.7 maturity index are indicative of mature sands. Using Field evidences and Bivariate plots of skewness versus sorting and mean versus sorting, a fluvial depositional setting was interpreted for the sediments
