Study Of Deep Clastic Favorable Reservoirs Geophysical Prediction

In this paper,deep clastic reservoirs are taken as the object of study.Geophysical methods,especially seismic inversion methods,are used to comprehensively predict deep clastic reservoirs and favorable reservoirs.In the study,reservoir elastic and physical parameter inversion,fluid identification and development parameter evaluation are mainly concerned.This paper discusses related issues encountered in deep clastic reservoir prediction,puts forward some new strategies,and combining theoretical model and actual data validation test,prove the feasibility and validity of the method.Deep clastic reservoir because of the great depth lead to the quality of seismic data is not high,and the reservoir is generally thin.With the influence of the frequency band of the seismic data,the resolution of thin reservoirs,deterministic inversion appeared to be inadequate.Stochastic inversion method,which has broken the limitation of the seismic frequency band and improved the longitudinal resolution of the reservoir,but the stochastic inversion has a large computational problem.Based on the theory of elastic impedance,the post-stack random inversion is used to reduce the computational load and improve the applicability of the method.The variation of the reservoir is faster and the lateral variation of the reservoir is more intense.Simultaneous inversion of seismic data is used to improve the stability of reservoir lateral prediction.Because of the buried depth of deep reservoir,the elastic parameter range of reservoir and surrounding rock overlap,which is bigger than shallow part,and it is difficult to distinguish reservoir only by elastic parameter.This paper proposes a joint inversion of elastic and petrophysical parameters to improve the accuracy of deep reservoir prediction by the cross validation of petrophysical and elastic parameters,which can reduce the cumulative error of indirect method of petrophysical parameter prediction;in order to improve the robustness of multi-parameter inversion,seismic faices controlled are introduced into the inversion process by constructing the low-pass filter matrix process,which effectively reduces the sensitivity of the inversion of constraint weight,and constrained inversion window range,clarify the geological significance of the inversion results.Based on the accurate prediction of reservoir physical properties and elastic parameters,the evaluation of reservoir fluid and development parameters has become an important part of reservoir prediction.Based on the theory of porous elastic medium,a new AVO approximation equation including fluid identification and brittleness evaluation is proposed.The effective fluid bulk modulus can overcome the influence of the porosity by varying linearly with water saturation.the product of the Young's modulus and the density should exhibit a high value and highlight the brittleness of the reservoir.The new AVO parameterization equation inversion can obtain the above two parameters simultaneously,thereby ensuring the consistency of the inversion results and avoiding repeated calculations,which makes it fully meet the requirements of large-scale inversion.