Seismic Inversion Techniques and Attribute Analysis for Accurate Well Placement in Offshore Niger Delta Basin, Nigeria

  • Authors

    • Tanguy W. Moukassa Pan African University, Life and Earth Science (including Health and Agriculture) https://orcid.org/0000-0002-9206-0873
    • Jerome E. Asedegbega GCube Integrated Services Limited
    • Solomon A. Adekola Obafemi Awolowo University Ile-Ife, Nigeria
    • Alexander Nwakanma University of Port Harcourt
    2024-08-04
    https://doi.org/10.14419/gwjaw719
  • 3D Static Model; Model-Based Inversion; Acoustic Impedance Cube; Rock Properties.

  • Abstract

    Before this study, simple methods like seismic attribute analysis have often been used for reservoir characterization with successes however, there is still the need to reduce exploration uncertainty to a negligible level and boost investors’ confidence. This study integrated seismic inversion with seismic attribute analysis to better characterize the reservoirs in MTW Field in deep-offshore Niger Delta Basin. Five (5) wells with complete suite of petrophysical logs, three-Dimensional (3-D) seismic data, checkshot and other well information were used. The well data were thoroughly quality checked, reservoirs were litho-stratigraphically delineated and used for petrophysical analysis across the wells. This was followed by seismic-to- well-tie, seismic interpretation, and seismic attribute analysis (Root Mean Square-RMS) generated using depth surface maps. 3-D static reservoir model and volumetric evaluation were carried out. Petrophysical properties were derived and distributed across the 3-D static model using sequential gaussian simulation algorithm to ascertain shale volume spread across the model. To improve the seismic resolution and reduce interpretation uncertainty at greater depth, model- based post-stack seismic inversion was performed to obtain acoustic impedance cube. Litho-stratigraphic and petrophysical analysis result revealed five reservoir sands (A, B, C, D, and E). Reservoir-A was seen to be more viable with a thickness of 13.42 m, high effective porosity of 27%, permeability of 3187.53 mD, low water saturation of 34% and low shale volume of 11% which are indication good reservoir quality and producibility. The seismic interpretation revealed thirty-one (31) growth and antithetic faults oriented in the NE-SW and NW-SE directions, respectively. The RMS result revealed high amplitude reflectivity which is a measure of zone of interest. Based on this, seven (7) prospects and three (3) leads were identified. The seismic inversion result shows a high level of accuracy with a correlation coefficient of 0.997; 0.997; 0.995; and 0.996 in MTW-001, MTW-003ST1, MTW-004ST1 and MTW-005 wells, respectively. The acoustic impedance successfully resolved and improved on the resolution of the seismic stacking velocity especially at reservoir layers and at depth deeper than 3600 ms. Acoustic impedance as a layer property has improved on the lateral and vertical resolutions of the data beyond what the usual seismic interval velocity could image thus, validating some of the prospects and leads identified in this study. This demonstrated that uncertainty can be reduced by a blend of RMS and seismic inversion in identifying reservoir for accurate placement of wells. It is therefore recommended that E and P operators should adopt the technique in their future hydrocarbon exploration endeavor in frontier and matured basins.

  • References

    1. Archie, G. E. (1942). The Electrical Resistivity Log as an aid in determining some reservoir characteristics. Journal of Petroleum Technology, Vol.5: pp.54-62. https://doi.org/10.2118/942054-G.
    2. Beka F.T., and Oti, M.N. (1995). The Distal Offshore Niger Delta: Frontier Prospects of a Mature Petroleum Province, In: M. N. Oti and G. Postma, Eds., Geology of Deltas,. A. A. Balkema, Rotterdam. 237-241.
    3. Doust H., and Omatsola E. Niger Delta In: Edwards, J. D., and Santogrossi, P.A. (1990). eds., Divergent/passive Margin Basins . AAPG, Memoir. 48:.239-248. https://doi.org/10.1306/M48508C4.
    4. Ejedawe, J.E., Coker, S.J.L., Lambert-Aikhionbare, D.O, Alofe, K.B. and Adoh, F.O. (1984). Evolution of Oil Generating Window and Gas Evolution of Oil Generating Window and Gas. AAPG Bulletin. 68: 1744-1751.
    5. Ekweozor, C. M., and Daukoru, E. M. (1994). Northern delta Depobelt portion of the Akata – Agbada Petroleum system, Niger Delta: In Magoon, L.B. and Dow, W.G. (Eds). The petroleum system from source to trap. American Association of Petroleum Geologists Memoir. 1994. 460: 599 – 613. https://doi.org/10.1306/M60585C36.
    6. Evamy, B.D., Haremboure, J., Kamerling, P., Knaap, W.A., Molloy, F.A., and Rowlands, P.H. (1978). Hydrocarbon habitat of Tertiary Niger Delta. American Association of Petroleum Geologists Bulletin. 62: 277-298. https://doi.org/10.1306/C1EA47ED-16C9-11D7-8645000102C1865D.
    7. Farfour, M., Wang, Y. J., and Kim, J. (2015). Seismic attributes and acoustic impedance inversion in interpretation of complex hydrocarbon reservoirs. Journal of Applied Geophysics. 114:.68-80 https://doi.org/10.1016/j.jappgeo.2015.01.008.
    8. Hilchie, D. W. (1978). Applied Openhole Log Interpretation (for Geologists and Petroleum Engineers). Geophysical well logging. pp 1 - 350
    9. Hospers, J. (1965). Gravity Field and Structure of the Niger Delta, Nigeria, West Africa. Geological Society of American Bulletin. 76: 407-422. https://doi.org/10.1130/0016-7606(1965)76[407:GFASOT]2.0.CO;2.
    10. Kaplan A., Lusser C.U, and Norton I.O. (1994). Tectonic Map of the World, Panel 10. American Association of Petroleum Geologists, Tulsa. Scale 1:10,000,000.
    11. Klett T.R.,Thomas S. Ahlbrandt, J.W. Schmoker and Dolton, J.L. (1997). Ranking of the world’s oil and gas provinces by known petroleum volumes. U.S. Geological Survey Open-file Report-97-463, CD-ROM. 56 – 58. https://doi.org/10.3133/ofr97463.
    12. Kulke, H. (1995). Nigeria. In: Kulke, H., Ed., Regional Petroleum Geology of the World, Part II: Africa, America, Australia and Antarctica. Berlin, Gebruder Borntraeger. 143-172.
    13. Maurya, S. P., and Sarkar, P. (2016). Comparison of Post stack Seismic Inversion methods: A case study from Blackfoot Field, Canada. Journal of Scientific & Engineering Research, 7:1091-1101.
    14. Nwachukwu, J. I. and Chukwurah, P. I. (1986). Organic Matter of Agbada Formation, Niger Delta, Nigeria. AAPG Bulletin. 70: 48-55 https://doi.org/10.1306/94885624-1704-11D7-8645000102C1865D.
    15. Olowoyo K. O. (2010). Structural and Seismic Facies Interpretation of Fabi Field, Onshore, Nigeria Delta. Boca Raton, Florida, USA. 1-25.
    16. Othman, A. A. A., Ewida, H. F., Fathi Ali M. M., and Embaby M. M. A. A. (2017). Reservoir Characterization Applying Seismic Inversion Technique and Seismic Attributes for Komombo Basin. Austin Journal Earth Science, 3(1):1020.
    17. Petroconsultants. (1996). Petroleum exploration and production database: Houston, Texas. Petroconsultants, Inc, P.O. Box 740619, Houston, TX 77274-0619.
    18. Short, K, and Stauble, A. (1967). Outline of geology of Niger Delta. American Association of Petroleum Geologists Bulletin. 51:761–779. https://doi.org/10.1306/5D25C0CF-16C1-11D7-8645000102C1865D.
    19. Stacher, P. (1995). Present understanding of the Niger Delta hydrocarbon habitat, In, M. N Oti and G. Postma (eds.), Geology of Deltas. Rotterdam, AA Balkema. 257–267.
    20. Veeken, P. C. H. and Da Silva, M. (2004). Seismic inversion methods and some of their constraints: Fisrt Break. https://www.researchgate.net/publication/277392423, 22:47-70. https://doi.org/10.3997/1365-2397.2004011.

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  • How to Cite

    W. Moukassa , T. . (2024). Seismic Inversion Techniques and Attribute Analysis for Accurate Well Placement in Offshore Niger Delta Basin, Nigeria (J. . E. Asedegbega, S. A. Adekola, & A. Nwakanma , Trans.). International Journal of Advanced Geosciences, 12(2), 84-97. https://doi.org/10.14419/gwjaw719