AVO effects of a hydrocarbon source-rock layer.pdf

GEOPHYSICS, VOL. 66, NO. 2 (MARCH-APRIL 2001); P. 419–427, 8 FIGS., 1 TABLE.
AVO effects of a hydrocarbon source-rock layer
Jos´e M. Carcione
sion, are essential for understanding the oil generation and mi-
ABSTRACT gration processes. Recent petrophysical analyses of petroleum
source rocks (Vernik and Landis, 1996) indicate that strong ve-
anic content of petroleum source-rock layers
locity anisotropy can be associated with the presence anic
can be determined from seismic data with a suitable AVO
matter and its distribution in the rock matrix. Hydrocarbon
technique. Since the source rock has a layered structure,
source rocks are laminated posed of kerogen,
the best forward model is a transversely isotropic layer
oil, water, and illite layers. When the wavelength of the seismic
between two isotropic half-spaces, parameterized by the
pulse is much larger than the thickness of the single layers, the
layer thickness and the amount anic material. This
finely layered medium behaves as a homogeneous transversely
limited number of parameters is essential to obtain a
isotropic (TI) material, whose stiffnesses can be obtained by
robust inversion method. Here, pute the PP- and
the so-called Backus averaging technique (Carcione, 2000).
PS-reflection coefficients of the source bed as a func-
A typical situation in the North Sea is represented by the