TITLE:
Anisotropy and Empirical Relations for the Estimation of Anisotropy Parameters in Niger Delta Depobelts
AUTHORS:
Iheanyichukwu P. C. Okorie, Joseph O. Ebeniro, Chukwuemeka N. Ehirim
KEYWORDS:
Anisotropy, Velocity, Depobelts, Transverse Isotropy, Seismic
JOURNAL NAME:
International Journal of Geosciences,
Vol.7 No.3,
March
25,
2016
ABSTRACT: The difficulty in
achieving well-to-seismic ties due to errors arising from wrong time-to-depth
conversions has been as a result of ignoring anisotropy in seismic processing.
Anisotropy plays a vital role in the processing and interpretation of seismic
data. In this work, an inversion method based on the elastic stiffness tensors
was adopted to estimate and quantify anisotropy in two depobelts using
petrophysical well logs in Niger delta (Central Swamp and Greater Ughelli).
Results show that the estimated delta (δ), epsilon (ε), gamma (γ)
and eta (η) exhibit a high degree of anisotropy in the shales than in
the sands. The parameters were observed to be higher in the Central Swamp than
the Greater Ughelli depobelt. This behavior could be associated with the alternating
sequence of massive shale and sand beds geologically observed within this
depobelt. This work was also able to derive empirical relations that could be
used in estimating these parameters in the depobelts once appropriate
information or data for any one parameter is available.