Estimation of Petrophysical Properties of Ajali Sandstone in Western Anambra Basin Using Granulometric Analysis
DOI: 10.23977/geors.2019.21001 | Downloads: 25 | Views: 3299
Edirin Akpofure 1, Ebiegberi Oborie 1
1 Department of Geology, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria
Corresponding AuthorEdirin Akpofure
Most sedimentary deposits have complex regional permeability and porosity variations which can be determined through various methods. The petrophysical properties of Ajali Sandstone such as permeability, porosity, and grain mean diameter were estimated using textural characteristics of the sediment from field data, petrography and grain size distribution. Grain-size distributions of sediment samples were determined by mechanical sieving. The porosity and permeability have been affected adversely by the moderate to poor sorting of grains. Whereas, fracture line, diagenetic imprints such as the solution, alteration and corrosion at grain margins and lack of cement have made the grains friable, thereby, increasing porosity. Sedimentary structures such as the reactivation surfaces and mud drapes which interspace the thick cross-bedded beds form seals which impede permeability. The porosity of the sandstone is very high and ranges mainly from 50% - 70%, with a few above 70%. Whereas, the least estimated permeability is 3.74 m/day and the highest is 724.55 m/day. A very complex variation exist in the permeability of the studied sandstone which may be due to the occurrence of the several large planar, trough and herringbone cross stratification, erosion and pebble lagged surfaces prevalent in the Formation. There is a strong correlation between permeability and porosity and the associated regression equation is expressed, with a correlation coefficient R² = 0.6795. Poor correlations exist between permeability and other grain size parameters such as grain mean diameter, d10 and d60.
KEYWORDSPermeability, Porosity, Grain size distribution, Sedimentary structures, Diagenetic Imprints
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Edirin Akpofure, Ebiegberi Oborie, Estimation of Petrophysical Properties of Ajali Sandstone in Western Anambra Basin Using Granulometric Analysis, Geoscience and Remote Sensing (2019) Vol. 2: 1-24. DOI: http://dx.doi.org/10.23977/geors.2019.21001.
 Akpofure, E., Etu-Efeotor, J.O. (2013a) Petrography of Ajali Sandstone in Ayogwiri – Fugar – Orame Area of Western Anambra Basin: Implication for diagenetic and depositional history. Journal of Environmental and Earth Sciences. Vol 3 No 5, p 104 - 113.
 Akpofure, E., Etu-Efeotor, J.O. ( 2013b) Influences of depositional environment on the sedimentary structures, biostratigraphy and textural characteristics of Ajali Sandstone in Ayogwiri – Fugar – Orame Area of Western Anambra Basin. European Journal of Scientific Research, Volume 103, Issue 4.
 Akpofure, E. Akana, S.T. (2016) Palaeocurrent and Facies Analysis Of Ajali Sandstone In Western Anambra Basin, Nigeria. Journal of Africa Earth Sciences. (Elsevier) 118 (2016) 75 - 86
 Amajor, L.C. (1987) Palaeocurrent, petrography and provenance analysis of the Ajali sandstone (Upper Cretaceous). Southeastern Benue Trough, Nigeria. Sedimentary Geology, vol.54 p.47-60.
 Chilingar G.V., Main R., Sinnokrot A. (1963) Relationship between porosity, permeability and surface areas of sediments. Journal of Sedimentary Petrology, 33: 759–765
 Folk, R.L., Ward, W. (1957) Brazos river bar: a study of the significance of grain size parameters. Journal of Sedimentary Petrology, 27, 3-26.
 Hoque, M. and Ezepue, M.C. (1977) Petrology and palaeogeography of the Ajali Sandstone. Journal Mining Geology. 14, 16-27.
 Jones, H.A and Hockey, R.D. (1964) The geology of part of South-Western Nigeria. Explanation of 1:250,000 sheets nos.59 and 68. Bulletin Geological Survey Nigeria, 31, 101pp.
 Kezdi, A. (1974) Soil mechanics, Elsevier Scientific Publishing Company, Vol. 1, P. 49; Elsevier, New York.
 Kogbe, C.A. (1976) Palaeogeographic history of Nigeria from Albian times. In: Geology of Nigeria (Edited by C.A. Kogbe). Lagos, Nigeria: Elizabethan publishing.
 Ladipo, K.O. (1986a) Tidal shelf depositional model for Ajali Sandstone, Anambra Basin, Southern Nigeria. Journal of African Earth Sciences, Vol. 5, No 2, pp 177-185, Nio & A van Gelder eds.
 Ladipo, K.O. (1988a) Paleogeography, Sedimentation and Tectonics of the Upper Cretaceous Anambra basin, Southeastern Nigeria Journal of African Earth Sciences.,v.7, p.815-821.
 Ladipo, K.O. (1988b) Examples of Tidal current Periodicities from Upper Cretaceous Sandstone (Anambra
Basin SE Nigeria). In Boer, P.L., Van, A. and Nio, S.D. (Eds). Tide Influenced Sedimentary Environments and Facies. D. Riedel Publ. Co., Dorgrecht, p,333-340.
 Nwajide, C.S. and Reijers, T.J.A. (1996) Sequence architecture in outcrops. Example from the Anambra Basin, Nigeria NAPE Bulletin, v.11, no.01, p.23-32.
 Powrie, W. (2004) Soil Mechanics: Concepts and Applications. 2nd Ed. Taylor & Francis 270 Madison Avenue, New York, NY 10016.
 Rahaman, M.A. (1976a) Review of the basement geology of South-Western Nigeria. In: C.A. Kogbe (Editor), Geology of Nigeria. Elizabethen Publishing. Lagos, pp. 41-58.
 Reyment, R.A. (1965) Aspects of Geology of Nigeria. Ibadan University Press, 133 pages, 18pl.
 Salem, H. S., 2001: Determination of Porosity, Formation Resistivity Factor, Archie Cementation Factor, and Pore Geometry Factor for a Glacial Aquifer, Energy Sources, 23:6, 589-596. http://dx.doi.org/10.1080/00908310152125238
 Simpson, A. (1955) The Nigerian coal field. The geology of parts of Onitsha, Owerri and Benue provinces. Geological Survey Of Nigeria Bulletin, no.24, 85p, 5pl.
 Tucker, M.E. (Ed) (1988) Techniques in Sedimentology. Blackwell Scientific Publications, Oxford, 394 pp.
 Visher, G.S. (1969) Grain size distributions and depositional processes: Journal of Sedimentary Petrology, v.39, pp. 1074-1106.
 Vukovic, M., and Soro, A., 1992, Determination of hydraulic conductivity of porous medla from grain-size composition: Water Resources Publications, Littleton, CO, 83 PP