Inferring Hydrocarbon Migration and Sealing Potentials of Some Shales of the Anambra Basin (South-Eastern Nigeria) from Their Paragenesis and Geotechnical Index Properties

Okogbue, C. O.; Ugwoke, Tochukwu S.

doi:10.1007/s10706-012-9538-x

Cited by 2 publications

(3 citation statements)

References 10 publications

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“…Few studies have investigated the sealing effectiveness of these shales. The study by Okogbue and Ugwoke (2012), based on the geotechnical indices of potential sealing layers, suggests that the shales of the Nsukka Formation have a relatively higher plasticity and toughness index than those of the Mamu Formation. This property predisposes the shales of the Nsukka Formation to deform in a ductile manner, which is a key attribute of good seal rocks (Downey 1994).…”

Section: Seal Presence and Effectivenessmentioning

confidence: 99%

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Signatures of key petroleum system elements: outcrop examples from the Anambra Basin, Southeastern Nigeria

Dim

Mode

Okwara

2018

J Petrol Explor Prod Technol

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Although several works have proved the existence of oil and gas in the Campanian to Maastrichtian strata of the Anambra Basin, it is still considered a frontier basin due to the challenges associated with interpretation of stratigraphy and structure arising from non-availability of subsurface data. This has led to poor understanding of the petroleum system and hindered exploration activity within the basin. This research paper aims to discuss the signatures of essential petroleum system elements, based on the study of high-quality outcrop examples. Detailed field studies reveal the presence of source, reservoir and seal rocks, and traps exposed within the four lithostratigraphic units outcropping in the basin, across the southeastern part of Nigeria. The shales of Enugu Formation, offer good source rocks. The shales, coals, coaly shales and sandstones with repeated occurrence of shale-silt-sand heteroliths of the Mamu Formation provide possible source and reservoir rocks. Thick extensive sandstones with clay laminae of the Ajali Formation offer potential reservoir that are partly compartmentalized. The shales with interstratified sandstone of the Nsukka Formation provide potential cap and overburden rocks. The presence of anastomosing fracture bands, extensional joints and faults, small-scale growth faults, and rollover anticlinal structures are good evidence of structural and stratigraphic configuration that could allow for possible migration, accumulation and entrapment of hydrocarbon. These recognized signatures of the key elements of a petroleum system and oil seeps encountered in the basin are an indication of the presence of an active petroleum system.

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Section: Seal Presence and Effectivenessmentioning

confidence: 99%

“…This property predisposes the shales of the Nsukka Formation to deform in a ductile manner, which is a key attribute of good seal rocks (Downey 1994). Shales of the Mamu and Enugu Formations may deform in a brittle manner with associated joints and faults, when subjected to shear stress (Okogbue and Ugwoke 2012).…”

Section: Seal Presence and Effectivenessmentioning

confidence: 99%

Signatures of key petroleum system elements: outcrop examples from the Anambra Basin, Southeastern Nigeria

Dim

Mode

Okwara

2018

J Petrol Explor Prod Technol

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“…The Basin has been extensively studied by various workers (Akande et al, 2007;Okogbue et al, 2012) for its coal and shale characterization. The paleogeography, sedimentation and tectonics are documented by such works as Murat, 1972;Ladipo, 1988;& Obi et al, 2001).…”

Section: The Study Areamentioning

confidence: 99%

Sedimentology and Permeability Distribution of the Ajali Sandstone around Odugbo, North Central Nigeria

Odedede¹,

Adaikpoh²

2013

JGG

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Ajali Sandstone around Odugbo, North Central Nigeria was studied in order to determine its sedimentological characteristics and permeability distribution. The study involves both field mapping, samples collection from different outcrops locations and laboratory analyses. Grain size analysis revealed that the sandstones are composed of medium grained (av. 1.50 ф), poorly sorted (av. 1.60 ф) and sub-angular to sub-rounded grains which indicate deposition close to the source area. Permeability values deduced from an empirical formula are generally low with an average value of 46.76md indicating that the sandstones have poor flow characteristics. The low permeability is considered to have resulted from weathering and grained dissolution during the formation of hematite cement. Petrographic study shows that the sandstones are composed of mainly quartz (av. 95.08%), feldspar (av. 2.55%) and mica plus rock fragments (1.19%), and suggests texturally mature and mineralogically mature quartz arenite. This study also presents the trend suggestive that sedimentary structures and depth of burial can be considerable factors affecting sandstone permeability.

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Inferring Hydrocarbon Migration and Sealing Potentials of Some Shales of the Anambra Basin (South-Eastern Nigeria) from Their Paragenesis and Geotechnical Index Properties

Cited by 2 publications

References 10 publications

Signatures of key petroleum system elements: outcrop examples from the Anambra Basin, Southeastern Nigeria

Signatures of key petroleum system elements: outcrop examples from the Anambra Basin, Southeastern Nigeria

Sedimentology and Permeability Distribution of the Ajali Sandstone around Odugbo, North Central Nigeria

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