Discussion on characteristics of time-lapse seismic differential waveform of thin oil layer

Time-lapse seismic differences reflect rock physical property change of oil reservoirs caused by oil field exploitation.In this papas the function is deduced between reflection coefficient change of acoustic impedance interface and oil layer impedance change,and diiferential waveform features of thin oil layer is analyzed.The larger change of oil field acoustic impedance is,the bigger difference amplitude is.The waveform features of thin oil layers are related only with oil layer acoustic impedance change.If only oil layer acoustic impedance increases,the waveform of the thin oil layer is the same as differential of seismic wavelet.The waveform is the same as 180°differential of seismic wavelet so long as oil layer acoustic impedance decreases.And the extent of difference amplitude caused by impedance decrease is more than equivalent impedance increase.