Methodology Of PS-to-PP Time Mapping And Simultaneous Inversion Using P-P And P-S Wave Seismic Data

Because of the need of the prospection of the lithologicalpool,it is imperative to implement reservoir prediction and fluid discrimination by the elasticparameter precisely inverted.The 3D-3C seismic prospecting has sprung up ,and the technology of the statics correction and the migration of the converted wave has been increasingly perfect,which contribute to promote the development of the simultaneous inversion by P-P and P-S wave.Because of the add of the converted wave,the conditional number and singularity of the matrix for inversion is decreased,and the precision of the inversion is improved,especially in the evaluation of the precision of the velocity of the shear wave.The inversion researched by this thesis is prestack AVA inversion based on the methodology of generalized linear inversion.By using the ADCIP provided by the prestack time migration as the input gather for inversion ,the RMS velocities of P-P and P-S wave via the velocity analysis of migration as the initial model for inversion and the log information as the restraint for the inversion,the prestack AVA inversion for three parameters including P wave velocity,S wave velocity and density is proformed via the precise Zoeppritz function by the idea of forward modeling interation.The problem of the matching of P-P and P-S data also as a difficult point in the exploration of 3D-3C seismic is the main factor affecting the precision of the inversion.This thesis presents a methodology of extraction of the average ratio of P-wave to S-wave velocity which is used to compute the scaler for mapping P-S time to P-P time by using the relation between the P-wave RMS velocity and the P-S wave RMS velocity.This thesis also reseaches the influence of the phase correction,AVA true amplitude recovery and partial stack in prestack gathers to the precision of the inversion. The inversion by only P-P wave data often can get a better evaluation of the P-wave velocity and density than of the S-wave velocity,while the inversion by only P-S wave data can often get a better evaluation of the S-wave velocity and density than of the P-wave velocity.So the simultaneous inversion by P-P and P-S data can get a good evaluation of these three parameters at the same time.