|dc.description.abstract||This thesis develops and tests a new technique which integrates information from well production and 4D seismic data directly in the data domain. This method is of value when seismic data are acquired by multiple surveys over the same area of a hydrocarbon reservoir. Sequences of 4D seismic changes can then be extracted over different time intervals from multiply repeated seismic surveys and these are cross correlated with identical time sequences of cumulative fluid volumes produced or injected from wells. The technique is applied to frequently repeated seismic surveys from three North Sea fields, including two compartmentalised reservoirs: the Schiehallion and Norne field, and a compacting reservoir: the Valhall field. Maps of well to seismic cross-correlations are proven to produce a strong, localised and stable signal in the connected neighbourhood of individual wells.
The correlation signatures from the Schiehallion and Norne application investigated in this thesis are the consequence of pressure performance due to reservoir compartmentalisation. In the Schiehallion study, the mapped results help identify the production signal related only to individual wells, thus leading to a better delineation of reservoir compartments. In the Norne study in particular, an extra reservoir volume connected to the original segment is highlighted by the technique. The reservoir simulation model is subsequently updated and a better match between the observed and simulated data can be achieved. The application to the compacting Valhall field involves using data from the Life of Field Seismic project, for which the 4D signature is dominated by compaction-assisted pressure depletion. For these data, both AI and time-shift attributes are found to have a remarkably consistent correlation with the well activity for selected groups of wells. Further, maps of these results possess sufficient fine scale detail to resolve and disentangle interfering seismic responses generated by closely spaced wells and localised zones of gas breakout along long horizontal producers. These case studies indicate our proposed methodology of uniting well data and 4D seismic and confirm that this does indeed provide an insightful product for dynamic interpretation of the producing reservoir.||