Study On Sonic Logging Response Characteristics Of Fracture Formation

During the process of oil and gas exploration and development,it is always a difficult problem to identify and evaluate fractured reservoirs.Through the numerical simulation of borehole acoustic field,the propagation characteristics are studied to provide theoretical basis for the identification and evaluation of fractures,and it is also of great significance for acoustic logging interpretation.Based on the theory of equivalent fracture medium,this paper analyzes the relationship between elastic parameters and fracture parameters of different cracks,such as inclusions,aspect ratio and density.The equivalent medium model of cracks is established based on linear-slip model and Hudson's model.The parameters of this model are easy-calculated and have clear physical meaning,which overcomes the shortage of previous theory.After theoretical deduction,this theory can analyze fracture parameters and anisotropic response quantitatively.The sound field in the borehole is numerically simulated using the finite difference technique with second order in time and fourth order in space.The full acoustic waveforms,snapshot and frequency spectrum analysis are presented.According to the above studies,the model of equivalent media in this paper fits the frequency and scale range of acoustic logging.And the characteristics of the borehole sound field propagation characteristics can be used to characterize the fractured reservoir media effectively.