Journal of Petroleum Geology, vol. 21(4), October 1998, pp. 467-482

THE MFAMOSING LIMESTONE IN SE NIGERIA: OUTCROP-SUBSURFACE CORRELATION AND RESERVOIR DEVELOPMENT

T. J. A. Reijers*

Key sequence-stratigraphic markers define intervals recognised in outcrops and wells in the Aptian-Albian Mfamosing Limestone Formation in SE Nigeria. These markers aid in outcrop-to-subsurface correlation. The influx of siliciclastics and sea-level fluctuations controlled carbonate production. Peritidal, lagoonal and reefal carbonates rim the igneous Oban Massif and reflect an initial relative sea-level highstand. Subsequent sea level fall was accompanied by the progradation of carbonates away from the exposed, siliciclastic-shedding hinterland, and maximal carbonate production took place during a sea-level lowstand, when an open-marine carbonate shelf and a mixed carbonate siliciclastic shoal co-existed side by side. In the Ituk area, wave action abraded the sea floor which was occasionally exposed, and hardgrounds and leached horizons were formed. Bed- and matrix-selective dorag dolomitisation improved the reservoir potential of the carbonates in certain intervals.