Study On Inconsistent Time-lapse Seismic Based On Rock Physics And Forward Modeling

With the production progress of hydrocarbon reservoirs,the recovery efficiency reduces rapidly.For well-developed exploration areas with more than two times of seismic acquisitions,the sufficient usage of existing seismic data is efficient in studying the dynamic change of reservoirs' geophysics properties,and therefore contributes to the further exploitation.Time-lapse seismic reservoir monitoring is an efficient process of acquiring and analyzing multiple seismic surveys,in order to image fluid-flow effects in a producing reservoir.Time-lapse seismic technique demands the multiple acquisitions at same site over calendar time with same observation system.While,due to the difference of acquisition target or other reasons,the observation systems and acquisition parameters are usually varying.As a result,the multiple surveys cannot be used in time-lapse seismic monitoring directly.To solve this inconsistent problem,we need to develop some methods to eliminate the inconformity,and further implement the dynamic monitoring of reservoir variation.To ensure the well application of time-lapse seismic technique in hydrocarbon reservoir monitoring,the following works are presented.Firstly,the moduli of reservoir rocks are inverted from logging data by nonlinear inversion algorithm,on the basis of rock physics theories.Secondly,the reflection characteristics are analyzed respectively by Zoeppritz equations and wave-equation numerical simulation,with the reservoir velocities derived from inverted moduli and corresponding density.By comparing the refection properties from Zoeppritz equations and numerical simulation,a correlation factor is derived to make connections of the above two reflection results.Furthermore,wave-equation forward modeling is performed for different observation systems of certain 3D geologic model,and based on the analysis of the simulation results,primary parameters influencing the time-lapse seismic are ascertained,and corresponding processing techniques are developed to eliminate the discordance of multiple surveys.In conclusion,with the assistance of inconformity eliminating process,time-lapse seismic monitoring technique can make full use of existing acquisition seismic data,and make contributions to the enhancement of oil recovery efficiency,as well as the determination of the remaining oil distribution.