Foraminiferal biostratigraphy, depositional environments and hydrocarbon source rock potential of sediments from five wells in the western offshore region of the Niger delta, Nigeria

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5495933

Adekoya, A A

The Tertiary lithostratigraphy of the Niger delta consists of three units: The Akata, Agbada and Benin Formations. The Akata formation is characterized by a uniform development of grey, silty, undercompacted marine shales, containing lenses of abnormally high pressured fine grained sandstones. These pro-delta shales were deposited predominantly under anoxic conditions, on the continental slope. The Akata Formation is of Paleocene to Early Miocene age. The Agbada Formation is of Miocene-Pliocene age, and consists of a paralic sequence of alternating sandstones and shales. These were deposited on the delta front, distributary channels and lower delta plain environments. The Benin Formation consists predominantly of massive, porous, freshwater-bearing sands, with local thin shale interbeds. This formation was deposited in alluvial environments, including the braided stream and meander belt systems of the upper delta plain. Foraminiferal biostratigraphic analyses were made of sediments from the Akata and Agbada Formations in the Okan-74, Mesan-B, Meji-29, ET-1, and EA-5 wells. Index planktonic foraminifera enabled the zonation of the individual stratigraphic sequences. Five benthonic foraminiferal zones and ten biofacies/biofacies complexes are defined and correlated across the study area. Rock evaluation pyrolysis results indicate that the sediments contain adequate organic matter for hydrocarbon generation, while the Tmax data confirm burial to depths corresponding to the oil generation window. The vitrinite reflectance data confirm that some of the sediments are mature, and hydrocarbons (predominantly gas) generation has taken place from the predominant type III kerogens present in the organic matter.

• Research Organization: Washington State Univ., Pullman, WA (USA)
• OSTI ID: 5495933
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
030200* -- Natural Gas-- Reserves
Geology
& Exploration
AFRICA
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CENOZOIC ERA
CHEMICAL REACTIONS
COASTAL REGIONS
CONTINENTAL MARGIN
CONTINENTAL SLOPE
DECOMPOSITION
DEPOSITION
DEVELOPING COUNTRIES
FOSSILS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GEOLOGY
HYDROCARBONS
KEROGEN
MACERALS
MATERIALS
MATURATION
MINERAL RESOURCES
NATURAL GAS DEPOSITS
NIGER RIVER
NIGERIA
OFFSHORE SITES
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC MATTER
PETROLEUM DEPOSITS
PHYSICAL PROPERTIES
PYROLYSIS
REFLECTIVITY
RESOURCE ASSESSMENT
RESOURCES
RIVER DELTAS
RIVERS
ROCKS
SAND
SANDSTONES
SEDIMENTARY ROCKS
SEDIMENTS
SHALES
SOURCE ROCKS
STRATIGRAPHY
STREAMS
SURFACE PROPERTIES
SURFACE WATERS
TERTIARY PERIOD
THERMOCHEMICAL PROCESSES
VITRINITE