We verify lateral consistency of seismic well ties by interpolating log data from all available wells along seismic structures using predictive painting and performing a blind well test. Our results using well logs and a 3D seismic dataset demonstrate that the proposed approach can consistently and accurately tie well log data to seismic.
The approach has some limitations. In the field data examples reported in this paper, we assume that the reference type log is representative of the entire stratigraphic column found in other wells; this assumption may cause challenges in plays where rapid stratigraphic variations such as unconformities, channels or clineoforms may be present. Additionally, we did not account for fluid variability in the rocks which can cause different well log responses in the same stratigraphic unit. While fluid substitution may further improve the results, the approach proposed in this paper provides a reasonable, first-order, approximation of the unknown well logs.
Although the uncertainty of the models compared to the true earth model is not considered in this paper, one can assume that each constraint added to the proposed workflow (fluid substitution, modeling, etc.) will cast the model into a range of more accurate results. We show, by using field data examples, that the proposed approach is a feasible workflow for overcoming the challenges with the conventional seismic-well tie workflows. Further refinement of the well log information should only improve the results.
The purpose of integrating seismic and well log data is to achieve reservoir characterization that is most consistent with all available data and achieves the highest possible resolution. Our approach includes previously ignored wells in seismic well ties and provides a method for verifying the consistency and accuracy of the results.