Method for predicting CO2 distribution in four-dimensional seismic data in CO2 geological sequestration

The invention relates to a method for predicting CO2 distribution in four-dimensional seismic data in CO2 geological sequestration. The method comprises the following steps: (1) simulating fluid elasticity parameter calculation under change conditions such as different underground stratum temperatures, pressures and brine mineralization degrees; (2) establishing a relation or a formula among elasticity modulus, shear modulus and pressure of dry rock based on a rock physics test of a rock core; (3) improving a fluid replacement method based on a Gassman equation; (4) carrying out shale correction on stratums; (5) utilizing different fluid replacement methods according to different CO2 filling manners based on fluid replacement calculation of a well model filled with CO2; (6) carrying out environment correction and high-precision depth-time conversion on logging information, simultaneously, calculating ray parameter gathers or angle gathers, and manually synthesizing a seismic record; (7) establishing a gradient-intercept crossplot of CO2 saturability and pressure change, and picking up CO2 fluid identifying factors changed along with the pressure change and the saturability change; and (8) applying the CO2 fluid identifying factors to actual seismic data, so as to identify and predict the underground CO2 distribution. According to the method, the distribution of CO2 sealed underground can be identified and predicted.