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