Geochemistry, heavy mineral and sedimentological analyses of potential reservoir sand samples from Kolmani River-1 well, Northern Benue Trough, Nigeria

Abstract

Forty ditch cutting samples were worked on, twenty each for trace elements and sedimentological analyses. A few of these samples were selected for the analysis of heavy minerals within the Bima sandstone and shale sandstone units. The samples were obtained from Shell Nigeria Exploration and Production Company from a depth of between 2414 m and 2785 m. The results showed high concentration values of Ca and K which indicate a low degree of weathering in the source area of the material forming the reservoir rock. A high concentration of Fe and Ti implies the presence of Fe and Ti bearing minerals in the source materials, and the abundance of metals like Cu (135–1629 ppm) and Zn (233–1411 ppm) implied a fine grain size for the sediments as this supports metal absorptivity. The probability curves indicate that the sediments were transported by saltation and suspension in shallow marine environment. The heavy mineral assemblage indicates that the sediments were mineralogically mature and suggest igneous and metamorphic sources. The sorting pattern shows that the distance of transport of materials was intermediate to far from their source. The reservoir rock of Bima Formation shows evidence of having fair to good potential and can hence hold fluids if other petroleum systems are in place.