A reliable 4D seismic attribute for joint inversion of seismic and production data

Abstract

A reliable 4D seismic attribute is required for its quantitative use along with production history data to update the reservoir model. Because of the noisy, less reliable 4D attributes computed from field seismic data, 4D seismic has historically been used for qualitative analysis only. We present the computation of an appropriate 4D seismic attribute and the analysis of 4D seismic data to estimate a less noisy real seismic 4D attribute, which can be compared with a synthetic 4D seismic attribute. The difference of the two 4D attributes computed from real and synthetic seismic data can then be minimized to update the reservoir model. The analysis is demonstrated on a real data example from Alba field. We investigate two types of 4D attributes summed over the reservoir: 1) the difference of squared seismic amplitudes, and 2) the square of the difference of seismic amplitudes. We prefer the second attribute, because this attribute is positive, the real data attribute matches better with the synthetic data attribute, and it is more appropriate for quantitative analysis. Although the preferred attribute is less sensitive to noise, preconditioning of the real data is must. For the Alba data set, we apply time shifts to align two real seismic datasets and FK filtering to attenuate crosscutting noises from 4D data.