Preliminary geochemical characterization of saline formation water from Miocene reservoirs, offshore Niger Delta
Taiwo Ayodele Bolaji, Michael N. Oti, Mike Onyekonwu, Taiwo Bamidele, Michael Osuagwu, Leo Chiejina, Precious Nneka Elendu
Abstract
. Saturation indices (SI) of selected mineral phases calculated using PHREEQC indicate that the dissolution of iron oxide and carbonate minerals may contribute major ions in the formation water. The preponderance of alkali elements suggests the presence of feldspars, which could have resulted from sediments through which the water flows. An inverse relationship is observed between the resistivity of formation water and its TDS, which could be used to calculate resistivity values of formation waters in the area if the TDS contributions are known. Chemical data suggest that the formation waters were derived from seawater, dominantly altered by reverse ion-exchange processes and subsequently by water-rock interactions. Multivariate statistical analyses (correlation and factor analysis) indicate multiple sources of enrichment of ions in the formation waters.