The application of sensitivity analysis in the source rock maturity history simulation:An example from Palaeozoic marine source rock of Puguang-5 well in the northeast of Sichuan Basin
Rao Song1,2 Tang Xiaoyin1,2 Zhu Chuanqing1 Hu Shengbiao1 WangJiyang1
1.State Kay Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences,Beijing 100029;2.The Graduate University of Chinese Academy of Sciences,Beijing 100049
By analyzing the influence of input model parameters to the output results，the sensitive parameters in the source rock maturity history simulation can be determined.In this paper，for example of Puguang5 well，we carry out the sensitivity analysis of erosion thickness during tectonic movements，paleosurface temperature and paleogeothermal gradient in the maturity history simulation of the Palaeozoic marine source rock in the northeast of Sichuan Basin，using Easy％Ro chemical kinetic model.The analysis results showed that the present maturity of the Palaeozoic marine source rocks is fully controlled by the erosion thickness during LateYanshan to Himalayan movement(since Late Cretaceous)，paleosurface temperature and paleogeothermal gradient during the late Early Cretaceous，while it is nothing to do with other factors.The Lower Cambrian source rocks maturity history simulation is affected by many geological parameters，including the paleogeothermal gradient and the paleosurface temperature during Hercynian，the erosion thickness during the Early Indosinian movement and the Late Yanshan to Himalayan movement and so on.The Lower Silurian source rock maturity history modeling is mainly affected by the paleogeothermal gradient during late Early Permian and Late Triassic in the study area.In compare with the Lower Cambrian and the Lower Silurian source rocks，the maturity history simulation of Lower Permian and Upper Permian source rocks have less affect on the uncertainty of denudation thickness of tectonic movements，the paleosurface temperature and the paleogeothermal gradient.Apart from the uncertainty of 10％ of paleogeothermal gradient during the Late Triassic，which results in a 16.4 Ma difference in the time when the Lower Permian source rocks comes into the late oil generation stage(Ro=1.3)； and the uncertainty of 50％ of erosion thickness during Late Yanshan to Himalayan movement，which made a 16.7 Ma difference in the time when the Upper Permian source rocks comes into the dry gas stage，the uncertainty of other geological parameter affects the maturity history simulation result of Lower Permian and Upper Permian source rock no more than 15 Ma.
. The application of sensitivity analysis in the source rock maturity history simulation:An example from Palaeozoic marine source rock of Puguang-5 well in the northeast of Sichuan Basin [J]. Chinese Journal of Geology, 2011, 46(01): 213-225.