A quantitative approach for chemical kinetics assessment of the vitrinite maturation within the overstressed areas.
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- Category: Материалы
- Published on Saturday, 03 August 2013 07:42
- Written by sergey.m.astakhov
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© Astakhov S.M.
A quantitative approach for chemical kinetics assessment of the vitrinite and kerogen maturation within the overstressed areas.
Close
to
natural processes modeling of the catagenetic maturation of the
sediments and
organic matter is the key for certainty and accuracy increasing of the
evaluation of the source rocks generation potential. Significant
efforts at the
second half of the 20th century for analyzing the laws of regional
catagenetic
zoning formation which works in the most parts of the sedimentary basin
(usually the central non-deformed areas). Against this background, the
central
question that motivates this paper is a well-known fact that the
maturation and
the maturation indicating parameters (such as vitrinite reflectance,
VR) increase
in the faulted, tectonized areas. It has become abundantly clear that
these areas
has additional missing organic matter (OM) maturation factors, except
the
temperature and time.
The analysis was based
on the original section from Preverkhoyan foreland and Vilyui basin
(Eastern
Siberia). When we refer to the geomechanical structural reconstruction
results,
everyone can observe the most important fact - the VR high values
corresponding
increase in the parameter responsible for the main compressive stress!
The
data from a few experiments not allow at this stage to estimate the
contribution of the mechanical energy into certain reactions (Ei)
kerogen
(vitrinite) transformation. Therefore, prior to the establishment for a
wide
practice of geochemical studies works on the pyrolysis of samples in
the
deformed and non-deformed state, it is assumed the following scheme for
"modification"
of the spectrum of the kinetic reactions involving dynamocatagenesis.
The
standard
model (Sweeney and Burnham, 1990) suggests that the temperature and
time can be
defined as the ones influenced the VR increasing. But
here we can enter the stress depended
value Estress to decrease the activation energy according the forth
standing
order. Decreasing the activation energy, we increase the reactions rate
that
lead to the observed transformation ratio (using the vitrinite
reflectance).
The
featured scheme combining geomechanical reconstructions
and kinetic calculations represents a real tool for modeling of the
dynamocatagenesis intensity using the current approaches existing in
software
packages for modeling hydrocarbon systems. The
use of the proposed scheme is reasonable in areas of direct proximity
(20-30
km, up to 50 km) with the orogeny structures, foldbelts, in areas of
complex
tectonics to reassess their resources.
The
large-scale experimental studies are needed to
determine the
kinetics of OM transformation of source rock samples from all over the
world in
the deformed and non-deformed conditions. In practice pyrolysis study
of all
the major source rock suites in the new version with the use of
deformations
and / or differential confining pressure are needed to readjust.
Additional
techniques of the paleotemperature studies of rock samples are need to
be
implemented as a verification. For example, the fluid inclusions
studies.