Fractural Detection Method Based On Nonlinear Complex Anisotropic Diffusion Filtering

Fractured reservoir detection by Geophysical method refers to detect and forecastthe spatial distributionof fractured reservoir underground has important significancefor reserves increased and increase yield of China. The general characteristics offractured reservoir are the heterogeneity of the complex reservoir lithology andphysical property and complicated variable distribution of reservoir space. Thesecomplexities bring reservoir detection a world of difficulty.Although a series of reservoir detection method based on seismic is proposed inthe world at present, due to the complexity and irregularity of fracture distribution andfracture development zone be always geologically complex area, the noise pollutionof the seismic signal is heavy and low signal-to-noise ratio (SNR). The drawbacks ofclassic fracture detection method are noise sensitivity, so accurate detection of thefractured reservoir is impossible.The method of diffusion filtering using partial differential equation is graduallyrecognized in recent years, and has been widely used in the fields of image de-noisingand enhancement, the noise be reduced, meanwhile, edge and linear texture beprotected and enhanced. Its development experiences liner to nonlinear stages,isotropic to anisotropy stages and real domain to complex domain stages. Consideringthe edge formed by seismic event contains abundant information of geological body,and low quality of seismic data in fracture development zone, it is necessary to protectand enhance seismic edge in signal de-noising for seismic interpretation. So thediffusion filtering method is suitable for seismic signal de-noising.For the problem of noise sensitivity of fractured reservoir detection method, anew method combining nonlinear complex anisotropic diffusion filtering (NCADF)and geometric attributes was proposed. Aiming to suppress noise、increase SNR and reduce the multi-solution probability. This article consists of five sections; Mainresearch contents of the article include the following aspects:(1) Geological and Geophysical basis of fractured reservoir detection. Theclassification、 geological fractures and geophysical response was studied, andresolution of seismic data、possibility and risks was also studied.(2)Theory and application of NCADF. The basic idea of anisotropic diffusion issignal processing in multi-scale space, similar to thermal diffusion. Filtering equationis essentially partial differential equation (PDE), clear physical meaning comparedwith probabilistic method and wavelet. This article first introduces of PDE andmulti-resolution analysis, then, liner diffusion and anisotropic diffusion, such as P-Mmodel and tensor. The method generalizes the diffusion in the complex processescomplex domain by combined with free Schr dinger equation, and nonlinear isdeveloped by adding a complex diffusion term to the shock filter. Iteration stoppingcriterion for NCADF is proposed, and the seismic de-noising practical application isanalyzed.(3)Fractured reservoir detection based on3D geometric attributes. the thirdgeneration Coherence Algorithm、Body Curvature and Ant Tracking were discussionfor fractured reservoir detection. Combination of NCADF and geometric attributeswas proposed for de-noising and edge enhancement and the method have a goodpractice in practical application.