Study On The Prediction Method Of Tight Reservoir Fracture Based On Anisotropy

Fractured oil and gas reservoirs,as a new kind of oil and gas resources,is a kind of unconventional resources with great potential and practical application value.With the development of technology and the increasing demand for oil and gas resources,the fractured oil and gas has important strategic significance in oil exploration.According to the characteristics of tight reservoir stratum medium,based on fracture anisotropy theory,the tight reservoirs fractures media model is builded.The use of staggered grid high-order finite difference numerical simulation,the simulation results for a variety of models to study and discuss the characteristics of seismic wave propagation in this type of medium,by comparing a series of different situations VTI,HTI got some new media model understanding and conclusions.On this basis,to characterize the physical properties of anisotropic parameters were analyzed by model test,get the results and analysis of the different parameters to verify the accuracy and reliability of the method.Study on the P wave azimuthal anisotropy in HTI medium,discuss different reflection coefficient changes with the angle of incidence with approximate formula and different degree of approximation of the approximate formula and conditions.On this basis,research HTI media reflection coefficient variation with azimuth,azimuthal anisotropy characteristics were studied based on a simplified approximation formula;fractured media azimuth seismic wave propagation characteristics and related laws of time has been got based on HTI media traveltime calculation and simulation,.According to the seismic wave azimuthal characteristics of amplitude and travel time in HTI medium,two kinds of methods for identifying and detecting fracture are studied in this paper.Based on the approximate formula of the reflection coefficient in the weakly anisotropicmedium,the equation is linearized,and the azimuth information of fracture can be obtained by using the least square method.According to the seismic traveltime information of different measuring lines and the nonhyperbolic characteristics of traveltime of seismic reflection wave,the information of fracture azimuth and development density can be obtained by using the different azimuth moveout velocity,the reliability and accuracy of the results are verified by the model test.Research on the prediction method of travel,the conventional method is to determine fracture orientation information by solving overdetermined equations.the traveltime in media or small differences in speed will cause pathological matrix,we can not get a reliable solution.For overdetermined problem,the adaptive value orientation line selection method,maximum energy approach by superimposing dynamic correction,calculated iterative control.Then take the fitting results weighted values,as the final result.the reliability of the results are verified by the model test.