--> Abstract: Theoretical Study Of Natural Tracers To Determine Migration Routes And Distances: Models And Applications, by Y. Yang, S. R. Larter, A. C. Aplin, and D. Carruthers; #90928 (1999).

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YANG, YUNLAI1, STEVE R. LARTER1, ANDREW C. APLIN1, and DAN CARRUTHERS2
1NRG, University of Newcastle upon Tyne, UK
2Permedia, Ottawa, Canada

Abstract: Theoretical study of natural tracers to determine migration routes and distances: models and applications

Information about the route and distance travelled by oils' from their source rocks is crucial to exploration activity but, cannot be explicitly provided by seismic or other remote-sensing surveys. Thus, molecular indicators (tracers) of the absolute or relative distance of oil migration have been sought for decades. We demonstrate here that the theoretical fate of tracers during secondary migration is quite complex. Migration distance, the inherent properties of the migration systems, the properties of the tracers, the volume of the oil in place in the reservoir, and multi-trap fill-spill sequence all affect tracer concentration. A mathematical model has been constructed and implemented as, a software package capable of being coupled to a basin flow' simulator. Comparison of model outputs and field data suggest: 1) Equilibrium tracer sorption on solid phases in the migration' pathway is the main process removing tracer from oil. 2) The tracer concentration is not uniquely related to migration distance but is more closely related to the migration distance divided by the volume of oil in place; under certain conditions tracer concentrations will not be strongly correlated with migration processes. 3) The trap filling sequence (spatial position of reservoirs) significantly influences the distribution of tracers. The potential applications of such models are: 1) locating missed reserves, since the model can help to decide whether a trap is sourced directly or via another trap; 2) helping to differentiate fracture from capillary pathways of migration through mudrock sequences. We illustrate the model and some applications.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas