The History of a Reservoir Model Become an Innovation Platform
Authors: Musca Claudio , Cossa Alessandro , Tarchiani Cristiano 
Published: June 2020

Innovative reservoir seismic characterization technologies, with massive integration of Seismic and Petrophysical data, were applied for the first time, almost ten years ago, to a green field since the appraisal phase. This seismic driven static model has been continuously kept alive during development and production, effectively supporting application of innovative technologies, operations and business decision processes. Main object of this paper is to present a global overview of how different methodologies were implemented and tuned while the model evolved, taking advantages of lessons learned to improve technical knowledge and set up new opportunities.

The initial model, based on five wells, was adopted to characterize the reservoir, with a robust link between lithology, elastic and dynamic properties. The innovative Petro-Elastic facies characterization, tuned at field scale for the next development phase, proved to be valid during the drilling campaign of more than twenty HA-HZ wells, with only minor adjustments required to propagate the model. An automated workflow for geostatistical simulations conditioned by seismic probability cubes of facies and petrophysical properties and multi-scenario risk analysis, including depth conversion and well calibration of seismic properties, generated Static and Dynamic models ready to be approached with a Computer Assisted History Match (CAHM)/ Ensemble based Methods. Properties distribution did not require new seismic inversion meanwhile updating the model, confirming the predictability of seismic in terms of average properties and the consistency of Rock Physics Model and Petrophysical characterization. To drill horizontal wells, geosteering activities were assessed by generating fine scale pre-job sector models. Optimization of well trajectories was not based only on seismic but on posterior probability of facies and petrophysical properties generated by a dedicated workflow. During drilling, real time integration of seismic inversion, wellbore data, and Ultra-Deep Azimuthal EM Reservoir Mapping allowed to effectively support well placement, providing real time stratigraphic interpretation of drilled sequences. The automated workflow permits now to investigate a wide distribution of realizations converging on a subset whose reservoir dynamic simulation are in agreement with the first years of production.

The model represented a chance to implement approaches and workflows deployed in our reservoir department and now applied in top projects as well as in the day by day activities and still it is a platform to test new approaches and available technologies. Single innovative items have been object of more than twelve publications or conference presentations. Ten years later, we can assert that multidisciplinary integration and continuous cooperation between the subsidiary, in charge of operations, and the HQ was the key for the successful field characterization and development.

For the future, this model could be a platform to test CAHM/ Ensemble based technology integrating also future 4D seismic data thanks to the initial tuned Petro Elastic facies model.