Among the several activities involved in oil exploration are the determination of hydrocarbon in-place and mechanical competency of the oil reservoir. The pressure regimes of the formation have also become vital properties which must be well known to ensure preliminary awareness of the hydraulic fracturing. This study seeks to adopt a prediction strategy of the overall geo-mechanical competency and strength of the formation, using a less stressful computational process and an empirical analysis, developed using three wells from ED BON area in parts of Niger Delta.
Elastic constants such as Poisson Ratio, Young's, Shear and Bulk moduli which are the parameters for characterizing rock mechanical properties were estimated, as well as the subsurface formation pressures and the associated fracture gradient using P-wave sonic and density logs.
The results from the analysis showed that there is correlation between elastic strength and fracture pressure.
Acknowledgements
Thanks to Schlumberger for providing Petrel software and Shell for providing the data for this research. The Authors also acknowledge Adekunle Ajasin University, for the financial and material support, especially the availability of work station to execute this research, and Victor Eyinla for his contributions in the writing of the computer program.
| [1] |
Dresser Atlas, Well logging and interpretation techniques. The course for home study, Dresser Atlas Publication, 1982. Acoustic logs, 33pp.
|
| [2] |
S. Babu, A. Sircar, A comparative study of predicted and actual pore pressures in Tripura. India, J. Petrol. Tech. Alternative Fuels 2 (9) (2011) 150-160.
|
| [3] |
D. Basu, D.K. Ghosh, A. Paul, Determination of dynamic elastic properties of rocks and fracture pressure gradient from sonic waveforms, Indian Journal of Geology 66 (1) (1994) 31-38.
|
| [4] |
B.E. Law, C.W. Spencer, Abnormal pressure in hydrocarbon environments, in: B. E. Law, G.F. Ulmishek, V.I. Slavin (Abnormal Pressure in Hydrocarbon Environments:Eds.), American Association of Petroleum Geologists Memoir 70, 1998, pp. 1-11.
|
| [5] |
D.D.J. Evamy, P. Haremboure, W.A. Kamerling, F. Knaap, A. Molloy, M.H. Rowlands, Hydrocarbon habitat of the tertiary Niger delta, Am. Assoc. Pet. Geol. Bull. 62 (1978) 1-39.
|
| [6] |
J.E. Ejedawe, Patterns of incidence of oil reserves in Niger Delta Basin, Am. Assoc. Pet. Geol. Bull. 65 (1981) 1574-1585.
|
| [7] |
P. Stacher, Present understanding of the niger delta hydrocarbon habitat, in: M. N. Oti, G. Postma (Geology of Deltas,Eds.), Balkema, Rotterdam, 1995, pp. 257-268.
|
| [8] |
H. Doust, E. Omatsola, Niger delta in edwards JD and santogrossi PA, in: Divergent/passive Margin Basin AAPG, vol. 48, 1990, pp. 201-238.
|
| [9] |
D.S. Eyinla, M.A. Oladunjoye,Estimating geo-mechanical strength of reservoir rocks from well logs (2014), J. Environ. Earth Sci. 4 (20) (2014) 38-43.
|
| [10] |
N.C. Dutta, Geopressure prediction using seismic data: Current status and road ahead, Geophysics 67 (2002) 2012-2041.
|
| [11] |
A.R. Huffman, The future of pore pressure prediction using geophysical methods, Lead. Edge 21 (2002) 199-205.
|
| [12] |
B.A. Eaton,in:The Effect of Overburden Stress on Geopressure Prediction from Well Logs SPE 3rd Symposium on Abnormal Pore Pressure, 1972 SPE paper # 3719, 1972.
|
| [13] |
B.A. Eaton, Fracture gradient prediction and its application in oilfield operations, J. Petrol. Tech. 1969 (1969) 1353-1360. October.
|
| [14] |
E.R.R. Crain, Crain's petrophysical handbook. Online Shareware Petrophysics Training and Reference Manual, 2013. https://www.spec2000.net/01-introduction.html.
|
| [15] |
Z. Chen, X. Wang, A. Atkinsonb, N. Brandon, Spherical indentation of porous ceramics: cracking and toughness, J. Eur. Ceram. Soc. 36 (2016) (2016) 3473-3480.
|
| [16] |
K.K. Nwozor, M.L. Omudu, B.M. Ozumba, C.J. Egbuachor, A.G. Onwuemesi, O.L. Anike, Quantitative evidence of secondary mechanisms of overpressure generation: insights from parts of onshore Niger delta, Nigeria, Petroleum Technology Development Journal: Int. J. 3 (1) (2013) 64-83.
|
| [17] |
J.P. Castagna, M.L. Batzle, R.L. Eastwood, Relationships between compressional-wave and shear-wave velocities in clastic silicate rocks, Geophysics 50 (1985) 571-581.
|
| [18] |
P. Avseth, H. Flesche, A.V. Wijngarden, AVO classification of lithology and pore fluids constrained by rock physics depth trends, Lead. Edge 22 (2003) 1004-1011.
|
| [19] |
S. Khamrat, S. Archeeploha, K. Fuenkajorn, Pore pressure effects on strength and elasticity of ornamental stones, Sci. Asia 42 (2016) (2016) 121-135, https://doi.org/10.2306/scienceasia1513-1874.2016.42.121.
|
| [20] |
D. Han, A. Nur, D. Morgan, Effects of porosity and clay content on wave velocities in sandstones, Geophysics 51 (1986) 2093-2107.
|
| [21] |
B.J. Kowallis, L.E.A. Jones, H.F. Wang, Velocity-porosity-clay content systematics of porosity consolidated sandstones, J. Geophys. Res. 89 (B12) (1984) 10355-10364.
|
| [22] |
C. Tosaya, A. Nur, Effects of diagenesis and clays on compressional velocities in rocks, Geophys. Res. Lett. 9 (1) (1982) 5-8.
|