The Niger Delta is a large, arcuate delta of the destructive, wave-dominated type. A sequence of under-compacted marine clays, overlain by paralic deposits, in turn covered by continental sands, is present throughout, built-up by the imbricated superposition of numerous offlap cycles. Basement faulting affected delta development and thus sediment thickness distribution.
In the paralic interval, growth fault associated rollover structures trapped hydrocarbons. Faults in general play an important role in the hydrocarbon distribution. Growth faults may even function as hydrocarbon migration paths from the overpressured marine clays. Depositional environments of reservoir sands strongly influence well productivity as well as recovery efficiency.
Le Delta du Niger est un delta très étendu, de forme arquée et de type destructif (par l'influence des vagues).
Une séquence d'argiles marines sous-compactées, recouvertes de dépôts paraliques, eux-mêmes surmontés par des sables continentaux, est présente partout; sa génèse est expliquée par la superposition imbriquée de nombreux cycles régressifs. La fracturation du socle a affecté le développement du delta et par conséquent la distribution des épaisseurs des sédiments.
Les hydrocarbures ont été piégés dans l'intervalle paralique de structures de type "rollover" associées à des failles de croissance. Les failles jouent en général un rôle important dans la distribution des hydrocarbures. Les failles de croissance peuvent même déterminer la migration des hydrocarbures à partir des argiles marines sous-compactées. L'environnement de dépôt des sables réservoirs influence fortement la productivité des puits ainsi que le taux de récupération des hydrocarbures.
found in 1955, and by 1958 production had started from the Oloibiri and Afam fields. A rapid increase in the number of discoveries followed.
By 1962 Shell-BP had relinquished more than 50% of its prospecting average. At present twelve companies are active in the Niger delta in cooperation with the Nigerian National Oil Corporation which recently has also started exploring on its own.
After a temporary setback during the 1967/70 civil war, production continued to rise rapidly and Nigeria is now the world's seventh largest oil producer with a production in June 1974 of 2.3 million bd. Gas reserves are also large and several LNG projects have been proposed.
The geological knowledge of the delta has reached an advanced stage but a number of problems remain.
The following article summarises present ideas on delta development, structural geology, sedimentology, oil migration and trapping.
The petroleum industry in Nigeria has a history which goes back to 1908-14 when a German company, the Nigerian Bitumen Company, drilled 14 wells in the coastal region, some 90 km east of Lagos.
Several bituminuous accumulations were found at shallow levels.
In 1937 Shell
