Local Update of Object-Based Geomodels
- Frode Georgsen (Norwegian Computing Center) | Anne R. Syversveen (Norwegian Computing Center) | Ragnar Hauge (Norwegian Computing Center) | Jan I. Tollefsrud (Roxar ASA) | Morten Fismen (Roxar ASA)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- June 2009
- Document Type
- Journal Paper
- 446 - 454
- 2009. Society of Petroleum Engineers
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- 632 since 2007
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The possibility of updating reservoir models with new well information is important for good reservoir management. The process of drilling a new well through to update of the static model and to history match the new model is often a time-consuming process. This paper presents new algorithms that allow the rapid updating of object-based facies models by further development of already existing models.
An existing facies realization is adjusted to match new well observations by changing objects locally or adding/removing objects if required. Parts of the realization that are not influenced by the new wells are not changed. A local update of a specified region of the reservoir can be performed, leaving the rest of the reservoir unchanged or with minimum change because of new wells.
In this method, the main focus is the algorithm implemented to fulfill well conditioning. The effect of this algorithm on different object models is presented through several case studies. These studies show how the local update consistently includes new information while leaving the rest of the realization unperturbed, thereby preserving the good history match.
Rapid updating of static and dynamic reservoir models is important for reservoir management. Continual maintenance of history-matched models allows for right-time decisions to optimize the reservoir performance. The process of drilling a new well through to updating of the static model and history matching of the new model is often a time-consuming process. Static reservoir models and history matches are updated only intermittently, and there is typically a 1- to 2-year delay between the drilling of a new well and the generation of a reliable history-matched model that incorporates the new information.
This paper presents new algorithms that allow rapid updating of static reservoir models when new wells are drilled. The static-model update is designed to keep as much of the existing history match as possible by locally adjusting the existing static model to the new well data. As the name implies, object models use a set of facies objects to generate a facies realization. Stochastic object-modeling algorithms have been developed to improve the representation of facies architectures in complex heterogeneous reservoirs and, thereby, to obtain more-realistic dynamic behavior of the reservoir models. We consider the main advantages of object models to be the ability to create geologically realistic facies elements (objects) and control the interaction between them, to correlate observations between wells (connectivity) explicitly, and the possibility of applying intraobject petrophysical trends.
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