Integrated Time-Lapse Reservoir Monitoring: The Amelia Field Case

By

A. Cominelli¹, L. Kovacic¹, A. Sturniolo¹, E. Poggiagliomi²

(1) ENI SpA - Agip Division, S. Donato Milanese, Italy (2) Former WesternGeco, N/A,

 Time-lapse seismic was used to assess the performance of the Amelia gas field (off-shore Italy) producing under strong water drive.

Objective of this work was the characterisation of main producing sand intervals by integrating two “legacy” 3D-seismic surveys and borehole data. A methodology, developed under the European project HUTS, has been proposed to test the integration of time-lapse information into the Amelia history match loop.

The work consists of these steps:

1. Rock Physics Characterization. The main reservoirs physical properties were defined by extensive core measurements/analyses at reservoir condition.

2. Integrated Time-lapse Processing of 3D-volumes to achieve high repeatability. Seismic processing parameters were determined for the two surveys using wells. Spectral equalization of wavelets in the seismic traces was performed to improve repeatability.

3. Integrated Multidimensional Petro-acoustic Calibration of the 3D-volumes. Microscopic properties of the reservoir rocks together with logs were used to estimate clay-content, porosity, saturation and pressure.

4. Simulator Rescaling and Petro-elastic Modelling. To compare dynamic simulation and 4D-data, the depth-migration of AI-volumes and related scaling to simulator cells were required. Seismic response of reservoirs was simulated through a petro-elastic model that enabled to generate synthetic AI from numerically simulated pressure and saturation distributions.

5. History Match using 4D data. Depth-migrated and simulated AI-data were iteratively reconciled by including a 4D-term in the HM loop.

This approach produced good repeatability between seismic volumes while the qualitative time-lapse analysis of the AI-volumes enabled to visualize fluids movement within the main pools.