Petrophysical Characteristics of Reservoir Sands in Sam-Bis Field, Greater Ughelli Depobelt, Niger Delta Basin, Nigeria

Yıl 2024, Cilt: 6 Sayı: 1, 37 - 47, 15.05.2024

Raphael Oaikhena Oyanyan

Öz

To understand the variations of petrophysical properties with paleoenvironments of deposition of reservoir sands, mathematical models were applied to a suit of wire line logs data to calculate thickness, volume of shale, porosity, permeability and fluid saturations. Twenty-one sand units were identified. The average sand thickness ranged from 2.6m in the fluvial distributary channel to 14.93m in the tidal channel. The average volume of shale ranged from 0% in some sand units of the mouth bar to 26.3% in a sand unit of the tidal channel. Effective porosity values ranged from 12.12% in a sand unit of distributary channel to 30.8% in a sand unit of mouth bar, while permeability values ranged from 96.3Md in a sand unit of distributary channel to 903.2Md in a sand unit of mouth bar. The cross-plot of porosity values against depth and permeability gave regression coefficients of 67.9 and 64.5, respectively. Therefore, there is a strong relationship between porosity and permeability, and with depth, it decreases gradually. Generally, the porosity values are fair to very good, while the permeability values are good to very good for hydrocarbon production. The order of increase in porosity with depositional environments is given as follows: fluvial distributary channel, lower/middle shoreface, point bar, tidal channel, and mouth bar. The tidal channel formed a thicker reservoir than the mouth bar, but the mouth bar formed a higher-quality reservoir due to the energy of the depositional environment. Rocks deposited in the same depositional environment have similar porosity values. Therefore, petrophysical properties are controlled by depositional processes, thickness, and depth. Only 14.3% of the identified reservoir sand units have hydrocarbon in commercial quantity with hydrocarbon saturations that ranged from 47.8 to 81.5%.

Anahtar Kelimeler

Niger Delta Basin, Reservoir sands, Petrophysical properties, Fluid saturation, Depositional environments

Kaynakça

• Archer, J.S., Wall, C., 1986. Petroleum engineering Principle and practice. Graham and Trotman Inc.
• Archie, G.E., 1942. The electrical Resistivity log as an aid in determining some reservoir characteristics. Petroleum Technology 5, 54-62.
• Asquith, G.B., Gibson, C.R., 1982. Basic Well Log Analysis for Geologists. AAPG, Tulsa.
• Avbovbo, A.A., 1978. Tertiary lithostratigraphy of Niger Delta. AAPG Bulletin 62, 295-300.
• Berg, R.R., 1986. Reservoir Sandstone. Prentice-Hall Inc., Eaglewood Cliffs, New Jersey 07632, p. 491.
• Bjørlykke, K., 2015. Petroleum Geoscience. From Sedimentary Environments to Rock Physics. Second Edition. Springer-Verlag Berlin Heidelberg, p. 666.
• Crain, E.R., 1986. The log Analysis Handbook. Quantitative log analysis method. Pennwell Books, Pennwell Publishing Company, Tulsa, Oklahoma USA 1, 20-352.
• Dewan, J.T., 1983. Essentials of modern open hole log interpretation. Pennwell publishing company Oklahoman, p. 361.
• Doust, H., Omatsola, E., 1989. Niger Delta. In: Divergent margin basins, J. D. Edwards and P. A. Santogrossi, eds., AAPG Memoir 48, 201-238.
• Dresser, A., 1982. Well logging and interpretation techniques. The course for home study. Dressser Atlas Publication.
• Edward, J. D., Santogrossi, P. A., 1990. Summary and Conclusion, in Edwards, J. D., and Santogrossi, P. A., eds., Divergent/ passive Basins, AAPG Tulsa, Memoir 48, 239-248.
• Egbele, E., Ezuka, I., Onyekonwu, M., 2005. Net-To-Gross Ratios: Implications in Integrated Reservoir Management Studies. Society of Petroleum Engineers (SPE), 98808, 1-13.
• Gier, S., Worden, R.H., Johns, W.D., Kurzweil, H., 2008. Diagenesis and reservoir quality of Miocene sandstones in the Vienna Basin, Austria. Marine and Petroleum Geology 25, 681-695.
• Hook, J.R., 2003. An introduction to Porosity. Petrophysics 44 (3), 205-212.
• Knox, G. J., Omatsola, M. E., 1987. Development of the Cenozoic Niger Delta in terms of the escalator regression model. [In:] Proceedings of the KNGMG Symposium ‘Coastal Lowlands-Geology and Geotechnology’. Kluwer Academic Publishers 181-202.
• Lien, T. Midtbø, R. E., Martinsen, O. J., 2006. Depositional facies and reservoir quality of deep-marine sandstones in the Norwegian Sea. Norwegian Journal of Geology 86, 71-92.
• Magoon, L.B., Dow, W.G. eds., 1994. The Petroleum System—From Source to Trap, AAPG Memoir, Tulsa, 60, p. 655.
• Nichols, G., 2009. Sedimentology and Stratigraphy. Wiley and Blackwell Publication (second edition), p. 432.
• Oyanyan, R.O., Oti, M.N. 2015. Down-dip cross sectional variability in sedimentological and petrophysical properties of shoreface parasequence reservoir, Niger Delta. Petroleum Technology Development Journal 5 (2), 92-117.
• Oyanyan, R.O., Oti, M.N., 2016. Heterogeneities and Intra Sand-Body Compartmentalization in Late Oligocene Delta-Front Deposit, Niger Delta, Nigeria. Current Research in Geoscience, Science Publications 6 (1), 47-64.
• Oyanyan, R.O., Soronnadi-Ononiwu, C.G., Omoboriowo, A.O., 2012. Depositional environments of Sam-Bis oil field reservoir sands, Niger Delta, Nigeria. Pelagia Research Library. Advances in Applied Science Research 3 (3),1624-1638.
• Reading, H.G., 2009. Sedimentary environments: processes, facies and stratigraphy. 3rd edition. Wiley Publication p.704.
• Reijers, J.J.A., Petters S.W., Nwajide C.S., 1997. The Niger Delta Basin: In the African Basin by Selley R. C. Elsevier Publication, New York, pp. 150-172.
• Rider, M.H., 2004. The Geological Interpretation of Well Logs. Blackie, Glasgow p. 280.
• Schlumberger, 1974. log interpretation manual applications, Vol. 1: Houston Schlumberger Well Services Inc.
• Schlumberger, 1991. Log interpretation chart. Schlumberger educational services publ. USA, p. 170.
• Schlumberger, 1985. Well evaluation conference Nigeria. Schlumberger international, Houston USA, pp. 135-145.
• Selly, R.C., 2000. Applied Sedimentology (second edition). Academic Press Publication, p. 543.
• Serra, O., 1989. Sedimentary environments from wire line logs Schlumberger publications, p. 43.
• Short, K.C., Stauble, A.J., 1967. Outline of Geology of Niger-Delta. A.A.P.G. Bulletin, 51, 716-779.
• Stacher P., 1995. Present understanding of the Niger-Delta hydrocarbon habitat in: M.N. Oti and G. Portma (Editors), Geology of Deltas. A.A. Balkema, Rotterdam, pp 257-267.
• Tuttle, M.L.W., Charpentier, R. R., Brownfield, M. E., 1999. The Niger Delta Petroleum System: Niger Delta Province, Nigeria, Cameroon, and Equatorial Guinea, Africa. U.S. Geological survey, Open-File Report 99-50 H, (No. 701901), 4-44.
• Weber, K.J., Daukoru, E.M., 1975. Petroleum geology of the Niger Delta: Proceedings of the Ninth World Petroleum Congress, Geology, London. Applied Science Publishers, Ltd., 2, 210-221.
• Worthington, P.E., 2011. The Petrophysics of Problematic Reservoirs. JPT. SPE 144688, 88-97.