2017_EJRNL_PP_DAVID_A__WOOD_1.pdf
Terbatas  Suharsiyah
» Gedung UPT Perpustakaan
Terbatas  Suharsiyah
» Gedung UPT Perpustakaan
Thermal maturity indices and modelling based on Arrhenius-equation reaction kinetics have played an
important role in oil and gas exploration and provided petroleum generation insight for many kerogenrich source rocks. Debate continues concerning how best to integrate the Arrhenius equation and which
activation energies (E) and frequency factors (A) values to apply. A case is made for the strong theoretical
basis and practical advantages of the time-temperature index (PTTIARR) method, first published in 1998,
using a single, carefully selected E-A set (E ¼ 218 kJ/mol (52.1 kcal/mol); A ¼ 5.45Eþ26/my) from the
well-established A-E trend for published kerogen kinetics. An updated correlation between PTTIARR and
vitrinite reflectance (Ro) is provided in which the PTTIARR scale spans some 18 orders of magnitude. The
method is readily calculated in spreadsheets and can be further enhanced by visual basic for application
code to provide optimization. Optimization is useful for identifying possible geothermal gradients and
erosion intervals covering multiple burial intervals that can match calculated thermal maturities with
measured Ro data. A memetic optimizer with firefly and dynamic local search memes is described that
flexibly conducts exploration and exploitation of the feasible, multi-dimensional, thermal history solution space to find high-performing solutions to complex burial and thermal histories. A complex deep
burial history example, with several periods of uplift and erosion and fluctuating heat flow is used to
demonstrate what can be achieved with the memetic optimizer. By carefully layering in constraints to
the models specific insights to episodes in their thermal history can be exposed, leading to better
characterization of the timing of petroleum generation. The objective function found to be most effective
for this type of optimization is the mean square error (MSE) of multiple burial intervals for the difference
between calculated and measure Ro. The sensitively-scaled PTTIARR methodology, coupled with the
memetic optimizer, is well suited for rapidly conducting basin-wide thermal maturity modelling
involving multiple pseudo-wells to provide thermal maturity analysis at fine degrees of granularity