Sequence Stratigraphy of Organic-Rich Rocks in the Niger Delta
Benson Akinbode Olisa, Abiola Adekunle

Abstract
Total organic carbon (TOC) analysis from well logs is combined with sequence analysis to develop a model for marine accumulation of organic-rich rocks in the Niger Delta. Pologbene-001 is selected for the analysis. Four sequences of HTB are recognized. The first is at a depth 9120 (2780m). The second HTB is at depth 9125ft (2781m). The HTB units were recognized by the combined characteristic patterns of gamma ray (GR), resistivity and sonic logs. TOC continuous sampling identified the system tracts, transgressive system tract (TST), lowstand system tract (LST), highstand system tract (HST) and the condensed sections. There are two possible areas for sedimentation, the marine and nearshore environments. The marine is devoid of oxygen whereas the nearshore is oxygenated. The marine sedimentation is recognized geophysically by high resistivity and transit-time whereas the reverse is the case in the nearshore.

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