Fluid Identification Technique Research Based On Seismic Data

Fluid identification technology based on seismic data palies an important role in rescrvoir predication.With oil-gas exploration developing,exploration areas transfer from structural hydrocarbon reservoir to lithologic hydrocarbon reservoir and subtle reservoir,fluid identification has became a new challenge and hourglass problem in reservoir predication.Propagation theory of seismic waves in fluid medium has been introduced in the paper firstly,which include effective medium theory,Gassmann theory,Biot theory and BISQ theory.Base on Biot theory,High-order finite difference method of elastic wave equation for two-phase isotropic medium is adopted,which is applied to forward modelling for one theory model.Through wave field snapshot,single shot record and minimum source-receiver distance profile in time domain,wave field feature of elastic wave,main seismic wave types and component have been analysed and researched.The actual complex gas reservoir model for guangan area has been established,so a suit method of model building is proposed,and the reflection of various waves on fluid is analysed.System researches have expanded based on three parameters(compressional velocity,shear velocity and density)attributes sets fluid identification and based on frequency information fluid identification technology.For three parameters attributes set fluid identification technology:the extraction method of three parameters has been introduced(prestack simultaneous inversion theory),the member of three parameters attributes sets have been generalized systematically and classified;the fluid identification of three parameters attributes sets have been stressly researched,the single attribute fluid identification method based on probability distribution and double attribute fluid identification method based on quantitative cross plot have been put forward,which have been applied to gas identification,the results indicate that the method is obvious.For frequency information fluid identification technology:the basic theory of fluid identification based on frequency information has been introduced,for inner and external factor affecting frequency,some steps have been proposed to attain reserved amplitude and frequency analysis data with high resolution,high S/N ratio;through the comparison of time-frequency analysis method, the high accuracy time-frequency analysis method has been selected to extract time-frequency attributes;the analysis method flow of common single frequency fluid identification has been proposed,according to the data of full frequency band,several anomaly zone modes of common single frequency attribute have segregated; incorporating converted wave and compression wave,fluid identification method based on PS wave combined time-frequency analysis has been proposed;the AVO property of various fluid type in frequency domain has been studied;the generalized fourier analysis method,Proni absorption filter has been introduced,and researched for anti-noise and for the seismic processing interpretation flow.The above technology have been applied to fluid identification of organic reef in WBT area in the east of Sichuan and fluid identification of clastic rock in GUANGAN area in the middle of Sichuan,the results show that the above methods are effective.At last,the above two technology have been integrated in the software.fluid identification technology is the worldwide problem,in the paper,fluid identification technology based on seismic data have been researched,good results have been attained,however there are some questions such as frequency-reserved question,to be solved furtherly.