1. LITTORAL STATUS IS LEGAL –ADMINISTRATIVE, NOT GEOLOGICAL:
Littoral or non-littoral classification is a boundary and governance concept. It does not determine the existence, continuity or productivity of hydrocarbon systems, which are controlled by basin geology, sedimentary architecture, structural traps and reservoir continuity across onshore, estuarine and offshore environments.
2. PETROLEUM SYSTEMS ARE BASIN-DRIVEN AND CONTINUOUS:
Hydrocarbon reservoirs in deltaic provinces extend seamlessly from inland basins through estuaries into shallow offshore shelf environments. Onshore, swamp, estuarine and nearshore offshore accumulations are part of a single petroleum system, and production in one terrain is often geologically connected to adjacent terrains.
3. ONSHORE AND OFFSHORE ATTRIBUTION IS OPERATIONAL, NOT GEOLOGICAL:
The distinction between onshore and offshore production is largely operational for regulation and revenue administration. Geologically, reservoirs straddle administrative boundaries and terrains. Attribution must therefore rely on geospatial plotting of well coordinates and reservoir geometry rather than political descriptors of terrain.
4. THE 200-METRE ISOBATH DEFINES NIGERIA’S NEARSHORE SHELF FOR DERIVATION PURPOSES:
The 200-metre isobath marks the edge of the shallow continental shelf environment that hosts prolific deltaic and shallow marine reservoirs. In Nigeria’s revenue practice, hydrocarbon accumulations landward of this contour are treated as nearshore resources for derivation, subject to lateral maritime boundaries between States.
5. NON-LITTORAL STATES CAN BE OIL-PRODUCING STATES:
Oil-producing status flows from basin position and reservoir endowment, not coastline possession. Non-littoral States located within productive sedimentary basins host mature source rocks, reservoirs and structural traps entirely onshore and within estuarine environments, thereby qualifying as oil-producing States.
6. NON-LITTORAL STATES CAN HAVE SHALLOW OFFSHORE/ESTUARINE PETROLEUM ENDOWMENT:
Where a State possesses a major estuary or river mouth opening into the sea, nearshore shelf environments contiguous to that estuary form part of the same petroleum system. Hydrocarbon accumulations within such shallow offshore zones less than the 200-metre isobath remain geologically linked to the State’s basin system, subject to recognized lateral corridors.
7. NIGERIA’S UPSTREAM STRUCTURE IS PREDOMINANTLY ONSHORE (NON-LITTORAL ENVIRONMENTS):
Approximately 70 per cent of Nigeria’s producing oil wells are located in onshore and swamp terrains, while about 30 per cent are offshore within littoral corridors. States such as Delta, Rivers, Imo, Abia, Anambra, Ondo and Edo host a higher concentration of onshore wells, reflecting the historical development pattern of the Niger Delta and adjoining inland basin extensions.
8. OFFSHORE CONCENTRATION IN AKWA IBOM WITH ONSHORE CONTINUITY INTO THE CROSS RIVER BASIN:
Akwa Ibom State accounts for the highest concentration of offshore production infrastructure in Nigeria. However, it also maintains extensive onshore and swamp production within reservoir systems that are geologically continuous with the Cross River Basin, underscoring shared source kitchens, migration pathways and reservoir architecture across State boundaries.
9. THE CROSS RIVER SCIENTIFIC CASE STUDY
DUAL ONSHORE AND SHALLOW OFFSHORE ENDOWMENT:
The Cross River Basin exhibits a distinctive petroleum system characterized by estuarine discharge, mangrove–tidal environments and an elongated nearshore continental shelf conducive to reservoir development. Cross River State possesses both significant onshore reservoir coordinates within the basin and offshore/estuarine wellheads located within the nearshore shelf less than the 200-metre isobath, consistent with basin-scale geological models.
10. POLICY IMPLICATION: GEOLOGY, NOT LABELS , SHOULD GUIDE RESOURCE ATTRIBUTION:
Petroleum attribution and derivation should be grounded in geospatial well coordinates, reservoir continuity and basin geology, not solely in littoral labels. Effective resource governance requires aligning administrative decisions with the scientific reality of continuous petroleum systems across onshore, estuarine and shallow offshore terrains.
@Cross River Economic Intelligence Team.
February 2026.
