Sensitivity analysis in thermal and maturity modelling

• Published in: Marine and petroleum geology 1996-06, Vol.13 (4), p.415-425
• Main Author: Nielsen, Søren B.
• Format: Article
• Language: English
• Subjects: basin modelling; hydrocarbon exploration; inversion; thermal reconstruction
• ISSN: 0264-8172; 1873-4073
• DOI: 10.1016/0264-8172(95)00093-3

Knowledge about the present and past thermal structure in sedimentary basins is central to understanding the evolution of sedimentary basins and for success in hydrocarbon exploration. The possibilities and limitations in resolving the palaeothermal structure by inversion of downhole temperature and vitrinite reflectance data are discussed by means of an example from the Danish Central Trough. The prediction of petroleum generation is sensitive to uncertainties in source rock temperature history and the kinetic parameters of kerogen degradation. The effects of uncertainties in surface temperature, heat flow, depth of burial, thermal resistivity structure and kinetic parameters are investigated using a previously developed stochastic method. Regarding the state of petroleum generation the number of safe statements based on numerical modelling essentially are reduced to three: 1) the source rock has not generated significant amounts of petroleum; 2) the source rock has released most of its petroleum potential; or 3) the source rock has released some of its petroleum potential. In the latter case the state of petroleum generation is best described by a cumulative distribution function of source rock transformation which reflects the effects of uncertainties in the basic modelling parameters. The probability of occurrence of a particular transformation ratio value, like those derived in traditional deterministic modelling, is zero. An example of application from the Danish Central Trough is given.