ABSTRACT: Numerical Basin-Modeling: Empirical and Stochastic Approaches as Alternatives to Determinism

Douglas W. Waples, Masahiro Suizu

Deterministic numerical simulation of maturation and migration processes in sedimentary basins has become quite popular in the last few

years. However, recent research indicates that many of the chemical and physical processes which are being modeled deterministically are actually much more complicated than previously believed. Examples include the kinetics of hydrocarbon generation, the mechanisms of hydrocarbon expulsion, and secondary migration. Weaknesses in our conceptual models for these processes will surely translate into more serious weaknesses or even failures of numerical models in actual applications.

Alternatives to purely deterministic modeling include developing models that are based loosely on theoretical foundations but whose details are controlled primarily by empirical data rather than theory; stochastic (probabilistic) models for processes for which either the conceptual model is weak or the input data are variable or uncertain; and models that combine aspects of both deterministic and stochastic approaches.

New theoretical descriptions are being developed for several processes that will permit their mathematical solutions to be rooted more firmly in empirical data. Examples include compaction as a function of time, temperature, lithology, and overburden; vitrinite reflectance as a function of time and temperature based on a chemical-kinetic approach; and shale permeability as a function of compaction rates. These and other phenomena required for basin modeling are incorporated into a combined deterministic/stochastic model.

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