Estimation of overpressures from porosity based method : a theoretical approach applied to the central/coastal swamp depo-belts of the Niger delta basin

  • Authors

    • Ubon Mkpese University of Port-Harcourt
    2017-12-04
    https://doi.org/10.14419/ijag.v6i1.8547
  • , Compaction Disequilibrium, Normal Compaction, Overpressure Mechanism, Shale Trend, Niger Delta.

  • Abstract

    The Depth-dependent compaction theory that variations in certain geophysical properties with depth; bulk density, formation resistivity together with sonic velocity being a reflection of the pressure regime is the basis for pore pressure prognosis study. Pore pressure prediction (PPP), when done accurately can be used to avert disaster and helps in safe drilling. A porosity-based model has been applied to predict overpressured zones in an onshore environment of the Niger delta basin. Zones with hard overpressures greater than a magnitude of 0.7 psi/ft are generally within 10000ft and below. Top of overpressures for studied wells ranges between 7000ft and 10000ft. Porosities in shale are of typical values ranging between 0.05 to 0.46. A robust concordance between PPP and MPP profiles for each of the wells validates the results here and confirms suitability of model to the studied area.

  • References

    1. [1] Bowers, G. L., (1995); Pore Pressure Estimation from Velocity Data: Accounting for Overpressure Mechanisms Besides Undercompaction: SPE Drilling and Completions, June, 1–19.

      [2] Carmichael, R. S., (1982); Handbook of Physical Properties of Rocks. CRC Press Inc. Boca Rahn, Florida. Vol. 2, 1-228.

      [3] Doust, H., and Omatsola, E., (1990); Niger Delta, in, Edwards, J. D., and Santogrossi, P.A., eds., Divergent/passive Margin Basins, AAPG Memoir 48: Tulsa, American Association of Petroleum Geologists, 239-248.

      [4] Eaton, B. A., (1975); the Equation for Geopressure Prediction from Well Logs. Society of Petroleum Engineers of AIME, paper SPE 5544. https://doi.org/10.2118/5544-MS.

      [5] Flemings, P.B., Stump B.B., Finkbeiner, T. and Zoback, M. (2002); Flow focusing in overpressured sandstones: theory, observations, and applications. American J. of Science, Vol. 302, 827–855. https://doi.org/10.2475/ajs.302.10.827.

      [6] Holbrook, P.W., Maggiori, D.A., and Hensley, R., (2005); Real-time Pore Pressure and Fracture Gradient Evaluation in all Sedimentary Lithologies. SPE Formation Evaluation, Vol. 10, No. 5, 215-222.

      [7] Jiao, J. J. and Zheng, M. V. (1998); Abnormal Fluid Pressures Caused by Deposition and Erosion of Sedimentary Basins. Journal of Hydrology, Vol. 13, 124-141. https://doi.org/10.1016/S0022-1694(97)00115-7.

      [8] Kumar, B., Niwas, S. and Mangaraj, B.K. (2012); Pore Pressure Prediction from Well Logs and Seismic Data. 9th Biennial Intl Conf& Exposition on Pet. Geophy.

      [9] Short, K.C. &Stauble, A.J., (1967); Outline geology of the Niger Delta. American Association of Petroleum Geologists Bulletin, Vol. 5, 761–779.

      [10] Swarbrick, R. E. and Osborne, M.J. (1998); Mechanisms which Generate Overpressure in Sedimentary Basins: a reevaluation. AAPG Bulletin, Vol. 81, 1023-1041.

      [11] Tingay, R. P., R. R. Hillis, C. K. Morley, R. C. King, R. E. Swarbrick, and A. R. Damit, (2009); Present-day stress and neotectonics of Brunei: Implications for petroleum exploration and production: AAPG Bulletin, Vol. 93, No. 1, 75–100 https://doi.org/10.1306/08080808031.

      [12] Traugott, M., (1997); Pore pressure and fracture gradient determinations in deepwater. World Oil, August, 815.

      [13] Tuttle, M., Charpentier, R., and Brownfield, M. (2015); the Niger Delta Petroleum System: Niger Delta Province, Nigeria, Cameroon, and Equatorial Guinea, Africa. United States Geologic Survey.

      [14] Ugwu, G.Z. (2015); An Overview of Pore Pressure Prediction Using Seismically–Derived Velocities. Journal of Geology and Mining Research, Vol. 7, No. 4, 31-40. https://doi.org/10.5897/JGMR15.0218.

      [15] Zhang, J. (2011); Pore Pressure Prediction from Well Logs: Methods, Modifications, and New Approaches. Earth-science Reviews, Vol. 108, 50-63. https://doi.org/10.1016/j.earscirev.2011.06.001.

      [16] Zijian, C., Jingen, D., Baohua, Y., Qiang, T., and Zhuo, C. (2015); the Improvement Methods of Pore Pressure Prediction Accuracy in the Central Canyon in Qiongdongnan Basin. IPCBEE, Vol. 85, No. 1.

  • Downloads

  • How to Cite

    Mkpese, U. (2017). Estimation of overpressures from porosity based method : a theoretical approach applied to the central/coastal swamp depo-belts of the Niger delta basin. International Journal of Advanced Geosciences, 6(1), 14-26. https://doi.org/10.14419/ijag.v6i1.8547

    Received date: 2017-10-23

    Accepted date: 2017-11-23

    Published date: 2017-12-04