The invention relates to the technical field of longitudinal migration distance of
natural gas, and discloses a method for determining longitudinal migration distance of organic thermogenic
natural gas by using a
delta C-Ro relationship, comprising the following steps: S1, acquiring current burial depth Dn and geochemical parameters of a target
natural gas reservoir; s2, based on the geochemical parameters, determining the cause type of the natural gas A and the gas
source rock of the natural gas A; s3, establishing a Ro-D evolution model L-Ro-D-of which the
vitrinite reflectivity of the gas
source rock changes along with the depth; s4, establishing a
delta C-Ro relation model L-Ro-Pg-of the natural gas corresponding to the gas
source rock; according to the invention, through fusion of multi-parameter geochemical comparison and a
machine learning
algorithm, probabilistic output of gas source rock attribution is realized, the risk of man-made misjudgment is significantly reduced, and the accuracy and reliability of cause type identification are improved; the thermal history dynamic model is coupled by adopting a
nonlinear regression algorithm, and
Bayesian inversion and MCMC sampling are introduced, so that not only is the
goodness of fit of the model improved, but also the
confidence interval of the Ro-D relationship is provided, and the
model prediction is more scientific and robust.