Vertical and Lateral Reservoir Compartmentalization in Ohaji Oil Field, Nigeria
Abstract:
The Ohaji oil field was evaluated for reservoir compartmentalization, oil samples were obtained from well heads of four (4) producing wells from both the short-string and long-string reservoirs. Whole oil analysis was performed on samples for m/z 71. The interparaffins were used for evaluation. The profile of the envelopes of m/z 71 chro matograms for all the oils for both short string and long string reservoirs indicate that there is no connectivity of the long and short strings reservoirs for the same well among the suite of wells studied, there is vertical compartmen talization. The use of interparaffins indicates lateral/horizonal compartmentalization for the short-string reservoirs, while the long strings reservoir shows lateral/horizontal connectivity between Well 1LS and Well 3LS. Vertical connectivity was also observed between the short string reservoir of Well 1SS and the long string reservoir of Well 2LS. This implies that several source kitchens within the volume of source rock could have charged the reservoirs via different migratory pathways, or the same source kitchen could have charged the reservoir via different migra tory pathways. The compartmentalized configuration of the reservoirs could have provided for different degrees of homogenization of reservoir fluids hence the differences in their compositional distributions.
