ABSTRACT: Single-Point Personal Computer Kinetic Modeling Applied to the Prediction of Oil Generation and Its Timing on a Passive Margin

N. B. Schoellkopf

Source rock maturation modeling is playing an increasingly important role in qualifying charge and composition risks by predicting source rock maturity and placing limits on the timing of oil generation.

Petroleum generation is simulated within a large area of a passive Atlantic-type margin using a single-point PC-based maturation model (MATOIL) and careful integration of geologic, seismic, geochemical, kinetic, and thermal data. The advantage of this one-dimensional approach is that it is conceptually simple and does not require a mainframe computer. However, unlike more sophisticated true two-dimensional models, the one-dimensional models typically have limited or nonexistent capabilities for backstripping of fluid dynamics. For all methods, critical review of the data is essential prior to modeling.

A successful maturation model requires a well-constrained thermal history and activation-energy database, in addition to a carefully reconstructed burial history. The present-day temperature distribution is accurately represented, using the best quality Horner-corrected BHTs, stabilized DST temperatures, and shutin temperatures. Paleotemperatures and heat-flow history are constrained by local geologic history and known present-day temperatures. Activation-energy distributions are measured on isolated kerogens representative of the principal source rock facies.

The test of a successful model is whether it fits the observed data. The calculated maturities obtained through modeling fit well with observed geochemical maturity indicators, such as vitrinite reflectance, T_max, production index, sterane isomerization, steroid aromatization, and porphyrin maturity. The delineated oil and gas windows are displayed two-dimensionally in cross section and in map form and are calibrated against field distributions, oil compositions, and oil/source rock correlations.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990