Improving the repeatability of seismic data is a key element of 4D seismic monitoring

摘要

The influence of the un-repeatability noise, which is caused by the disagreement of zero-time or the error of horizontal position or wavelet in two surveys and data processing, on 4D seismic monitoring is analyzed by forward modeling. The results show that the influence of zero-error and horizontal position error on 4D seismic monitoring is related not only to the amplitude of real seismic anomaly caused by reservoir fluid variation but also to the lateral velocity variation and to the angle of layers. High horizontal position precision and a small zero-error are necessary for a weak seismic anomaly, when the lateral velocity variation and the angle of layers are larger, we should improve the horizontal position precision. The un-repeatability noise equal to 3. 31% of the maximum amplitude of pre-waterflood seismic profile in seismic difference profile can be caused for the main frequency error of 1Hz and about 12.4% for 5Hz main frequency error. In the precondition of reservoir variation meets the request of 4D seismic monitoring, the height of the un-repeatability noise will become the decisive factor for 4D seismic monitoring, and so improving the repeatability of 4D seismic data is the key problem of 4D monitoring successful.