“Oil flows from reservoirs, not from maps; derivation must follow geology, not cartography.”
This one-line principle captures a foundational truth of petroleum science and public policy: hydrocarbons do not obey political boundaries drawn on paper.
They accumulate and migrate within subsurface geological formations. Any credible system of oil well attribution and derivation must therefore follow reservoir geology, not merely surface plotting of wellheads or provisional cartographic lines.
In Nigeria’s upstream petroleum practice, the Unity of Deposit (Reservoir Continuity) Rule is well known. It holds that where a hydrocarbon reservoir extends across more than one jurisdiction, benefit must be attributed on the basis of the geological location and continuity of the reservoir.
In policy terms, the rule is simple and fair: “Hydrocarbon resources shall be attributed for derivation and revenue purposes on the basis of the geological location and continuity of the reservoir as determined by verified coordinates and subsurface mapping by relevant technical agencies; where a reservoir straddles inter-State boundaries, derivation shall follow reservoir continuity rather than mere surface wellhead location or provisional administrative maps.”
This is not novel theory. It is the logic that has guided inter-State oil well reconciliation exercises across Nigeria for over two decades.
The disputes between Rivers and Bayelsa, Imo and Rivers, Anambra and Delta, and Ondo and Delta were all resolved by recourse to reservoir mapping and geological continuity, not by a simplistic reading of surface coordinates alone.
The same scientific standard must apply to the Cross River–Akwa Ibom context.
Cross River’s Maritime Territory and the Calabar Estuaries
Cross River State’s petroleum endowment is inseparable from its maritime territory and estuarine systems. The Calabar Estuaries—comprising the Cross River Estuary and the adjoining Akwayefe estuarine complex—form part of a dynamic sedimentary environment that links the Niger Delta petroleum system with the Calabar Geological Flank.
These estuaries are not empty waters; they are conduits of sedimentation, reservoir development and hydrocarbon migration.
The failure to fully demarcate maritime boundaries after the ICJ judgment and the Green Tree Agreement, as well as the reliance on provisional cartographic models, has obscured the geological reality beneath these waters.
Yet geology is indifferent to administrative ambiguity. Reservoirs extend beneath estuaries, across state boundaries and into contiguous offshore formations. Where those reservoirs lie within Cross River’s subsurface space, Cross River is entitled—scientifically and equitably—to benefit.
The Geological Case: Calabar Flank, Agbada, Akata and Inland Reservoir Systems
Cross River’s eligibility as an oil producing state is not a political claim; it is a geological fact pattern. The State sits astride significant petroleum systems and sedimentary architectures:
Calabar Geological Flank:
The southeastern extension of the Niger Delta petroleum province, hosting sedimentary sequences that interface with productive offshore systems. This flank provides structural and stratigraphic conditions conducive to hydrocarbon traps.
Agbada Formation:
The principal reservoir-bearing formation of the Niger Delta, composed of alternating sands and shales. Extensions of Agbada sand bodies, through deltaic and estuarine processes, underpin reservoir continuity into the Calabar Flank and adjoining estuarine zones.
Akata Formation:
The major source rock of the Niger Delta petroleum system. Hydrocarbon generation from Akata shales migrates upward into Agbada reservoirs, including those that straddle coastal and estuarine boundaries adjoining Cross River’s maritime space.
Akpet Central – New Netim Sandstone System:
Inland sedimentary units within Cross River that demonstrate reservoir-quality sandstones and hydrocarbon potential, affirming that the State’s petroleum endowment is not confined to offshore narratives alone.
Oban Massif and Limestone Belts:
The Oban Massif provides the crystalline basement framework, while adjoining limestone and sedimentary belts form structural margins that influence trap formation, migration pathways and reservoir compartmentalization along the southeastern Niger Delta margin.
These geological elements together establish that Cross River is embedded within a functioning petroleum system. Reservoir coordinates identified within its maritime and estuarine subsurface are therefore not anomalies; they are consistent with regional petroleum geology.
Reservoir Coordinates, Not Cartography
The debate over oil producing status often collapses into arguments about littoral status, surface boundaries or historical administrative maps. This is a category error. States do not become oil producing because they are littoral; many littoral states are not oil producing. Conversely, several non-littoral states in Nigeria are oil producing because their reservoirs lie beneath their land territory.
The decisive factor is not proximity to the sea but subsurface hydrocarbon occurrence proven by coordinates and reservoir mapping.
Cross River deserves recognition as an oil producing state because its reservoir coordinates demonstrate hydrocarbon presence within its subsurface territory, including the Calabar Estuaries and the Calabar Flank petroleum province. To deny this on the basis of surface cartography is to elevate maps above geology and to substitute administrative convenience for scientific truth.
A Call for Evidence-Based Attribution
Nigeria’s energy governance must be anchored in evidence. The agencies charged with oil well attribution—the NUPRC, NBC, RMAFC, OSGOF and the Office of the Accountant-General—possess the technical capacity to determine reservoir continuity through seismic data, reservoir models and verified coordinates.
Where these data show that reservoirs extend into Cross River’s maritime and estuarine subsurface, derivation must follow.
The principle bears repeating:
“Oil flows from reservoirs, not from maps; derivation must follow geology, not cartography.”
Recognising Cross River State as an oil producing state on the basis of its reservoir coordinates and geological reality is not an act of political generosity. It is an act of scientific integrity, legal consistency and national fairness.
By John Gaul Lebo LLM,
LBS Harvard Alumni, Cross River Economic Intelligence Team February 2026
