ABSTRACT: The technical and commercial benefit of constrained maturation modelling
Hegarty, Kerry A.1, Sara S. Foland2, Paul F.
Green1, and Ian R. Duddy1
(1) Geotrack International, Melbourne,
Australia
(2) Geological Society of America, Boulder, CO
We refer to "constrained basin modelling" as an approach whereby the key
factor(s) controlling the outcome of a model are identified near the commencement of the
modelling effort. These key factors are then determined independently and used as a
cornerstone in subsequent modelling. This approach, in contrast to inferring or assuming a
key factor(s) offers essential advantages in exploration. For example, in most, if not all
sedimentary basins, the single key factor governing the maturity of a unit, is the
MAGNITUDE
of heating. However, the petroleum system and successful exploration relies not
just on accurate knowledge of the level of heating, but critically depends on the timing
of maturation versus trap formation. Thus for maturation modelling to be commercially
relevant not only the
magnitude
of maximum paleotemperature but also the timing of maximum
paleotemperature must be determined independently of the modelling exercise. Apatite
Fission Track Analysis (AFTA) can give an independent measure of the time and
magnitude
of
paleo-heating event(s). An example of the practical benefits of constrained basin
modelling is offered by results from the Eischeid-1 well (Midcontinent Rift System), where
AFTA has forced the revision in timing of maximum paleotemperature by ~700 Ma (to ~300-200
Ma), severely impacting assessment of the petroleum system (where ~1Ga was previously
assumed). The luxury of experimenting with a broad suite of basin models is no longer
viable in today's commercial setting. The efficient construction of accurate basin models
is now essential and demands minimizing the time spent on unnecessary unknowns,
identifying the key factors controlling the result, and measuring these factors directly,
where possible.
AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia