Sequence stratigraphy and depositional sequence interpretation: A case study of “George” Field, offshore Niger Delta, Nigeria

Abiola, O.; Olowokere, Mary Taiwo; Ojo, John Sunday

doi:10.1016/j.ptlrs.2017.12.001

Cited by 9 publications

(6 citation statements)

References 1 publication

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“…It could also be defined broadly as the historical geology of stratified rocks. More importantly, sequence stratigraphy can be simply put as the subdivision of sedimentary basin fills into genetic packages bounded by unconformities and their correlative conformities [6,7]. Sequence stratigraphy is largely used to provide a chronostratigraphic framework for the correlation and mapping of sedimentary facies and for stratigraphic prediction.…”

Section: Sequence Stratigraphymentioning

confidence: 99%

“…2 shows the typical diagrammatical illustration of highstand systems tract. Depositional systems may be similar initially to those in the transgressive systems tract, but the infill of shelf areas by progradation, and the decrease in the rate of relative sealevel rise, may lead to a decrease in tidal influence during a highstand systems tract, and a decrease in the amount of coal, and of overbank, lagoonal and lacustrine shales [7,9].…”

Section: Highstand Systems Tractmentioning

confidence: 99%

“…The second dimension is the building up of a structural profile of the sedimentation putting in cognizance the tectonic effects such as folding and faulting. The recognition of the third dimension in the vertical profile helps to reconstruct the detailed picture of interacting and interrelated subenvironments that cannot be obtained by simple comparison of lithological characteristics of different modern environments [2].…”

Section: Introductionmentioning

confidence: 99%

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Delineation of Stratigraphic Units in Xyz Field of Niger Delta Using Geophysical Logs

Ekeh

Uko

Eleluwor³

et al. 2019

Pakistan Journal of Geology

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Geophysical well logs were used to delineate the stratigraphic units and system tracks in the XYZ Field of the Niger Delta. The gross percentages for sand levels range from 93-96% in the shallow levels to 60-66% in the deeper levels. Porosity values ranged between 27% at shallower sections and 9% at deeper depths. Six depositional sequences were identified and categorized into their associated system tracts. Porosity decreases with depth in normal compacted formation for both sandstone and shale units. Surface porosity for sandstone is 42%, and for shale it is 38.7% from extrapolation of sub-surface porosity values to the surface. The depth to the base of Benin Formation is highly variable ranging between 1300 and 2600m. This study reveals the possibility to correlate sand levels over long distances which enables inferring porosity values laterally. The knowledge of the existent stratigraphic units, the Benin, Agbada and Akata Formations and their petrophysical parameters such as porosity, lateral continuity of the sands and shales, the variation of the net-to-gross of sands with depth, enables the reservoir engineer to develop a plan for the number and location of the wells to be drilled into the reservoir, the rates of production that can be sustained for optimum recovery. The reservoir engineer can also estimate the productivity and ultimate recovery (reserves) using the results on this work.

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Section: Sequence Stratigraphymentioning

confidence: 99%

Section: Highstand Systems Tractmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Delineation of Stratigraphic Units in Xyz Field of Niger Delta Using Geophysical Logs

Ekeh

Uko

Eleluwor³

et al. 2019

Pakistan Journal of Geology

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“…Effective porosity for reservoirs B and C is relatively high, as it falls in the range of 5-40%. The proposed qualitative classes by Abiola et al (2018) were modified and used as a guide for the classification of effective porosity (Table 3). The hydrocarbon region has effective porosity ranging from 15 to 30% and average porosity value as computed from the well logs to be 0.26 or 26% (Table 2).…”

Section: Effective Porositymentioning

confidence: 99%

“…From the permeability computed, it could be observed that the reservoir zones have high permeability (100 to > 1000 mD). The permeability was qualitatively interpreted after Abiola et al (2018), which is indicative of good-to-excellent permeability; it means the reservoirs can transmit hydrocarbon in commercial quantity (Table 3).…”

Section: Permeabilitymentioning

confidence: 99%

Transition zones analysis using empirical capillary pressure model from well logs and 3D seismic data on ‘Stephs’ field, onshore, Niger Delta, Nigeria

Abiola

Obasuyi

2019

J Petrol Explor Prod Technol

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Capillary pressure is an important characteristic that indicates the zones of interaction between two-phase fluids or fluid and rock occurring in the subsurface. The analysis of transition zones (TZs) using Goda (Sam) et al.'s empirical capillary pressure from well logs and 3D seismic data in 'Stephs' field, Niger Delta, was carried out to remove the effect of mobile water above the oil-water contact in reservoirs in the absence of core data/information. Two reservoirs (RES B and C) were utilized for this study with net thicknesses (NTG) ranging from 194.14 to 209.08 m. Petrophysical parameters computed from well logs indicate that the reservoirs' effective porosity ranges from 10 to 30% and the permeability ranges from 100 to > 1000 mD, which are important characteristics of good hydrocarbon bearing zone. Checkshot data were used to tie the well to the seismic section. Faults and horizons were mapped on the seismic section. Time structure maps were generated, and a velocity model was used to convert the time structure maps to its depth equivalent. A total of six faults were mapped, three of which are major growth faults (F1, F4 and F5) and cut across the study area. Reservoir properties were modelled using SIS and SGS. The capillary pressure log, curves and models generated were useful in identifying the impact of mobile water in the reservoir as they show the trend of saturating and interacting fluids. The volume of oil estimated from reservoirs B and C without taking TZ into consideration was 273 × 10 6 and 406 × 10 6 mmbbls, respectively, and was found to be higher than the volume of oil estimated from the two reservoirs while taking TZ into consideration which was 242 × 10 6 and 256 × 10 6 mmbbls, respectively. The results have indicated the presence of mobile water, which have further established that conventionally recoverable hydrocarbon (RHC) is usually overestimated; hence, TZ analysis has to be performed for enhancing RHC for cost-effective extraction and profit maximization.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Sequence stratigraphy of subsurface upper Eocene-lower Oligocene deposits, Dahomey Basin, Southwestern Nigeria: palynological and palynofacies approach

et al. 2021

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Sequence stratigraphy and depositional sequence interpretation: A case study of “George” Field, offshore Niger Delta, Nigeria

Cited by 9 publications

References 1 publication

Delineation of Stratigraphic Units in Xyz Field of Niger Delta Using Geophysical Logs

Delineation of Stratigraphic Units in Xyz Field of Niger Delta Using Geophysical Logs

Transition zones analysis using empirical capillary pressure model from well logs and 3D seismic data on ‘Stephs’ field, onshore, Niger Delta, Nigeria

Sequence stratigraphy of subsurface upper Eocene-lower Oligocene deposits, Dahomey Basin, Southwestern Nigeria: palynological and palynofacies approach

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