Modeling Uncertainties in Carbonate Karstic Reservoirs: Presentation of a Tool and its Application to a Real Field Case in Russia (Russian)
- Pierre Biver (Total SA) | Christian Longis (Total SA) | Emmanuel Penna (Total SA) | Andrey Ovsyannikov (Total SA)
- Document ID
- Society of Petroleum Engineers
- SPE Russian Oil and Gas Exploration and Production Technical Conference and Exhibition, 16-18 October, Moscow, Russia
- Publication Date
- Document Type
- Conference Paper
- 2012. Society of Petroleum Engineers
- 3.3.2 Borehole Imaging and Wellbore Seismic, 5.1.3 Sedimentology, 5.1.5 Geologic Modeling, 5.1.2 Faults and Fracture Characterisation, 5.5 Reservoir Simulation, 5.8.7 Carbonate Reservoir
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This paper is presenting a methodology to model karstic diagenesis with geometrical processes. This fast procedure is efficient to model karstic drainage zones in an uncertainty framework with multiple realizations. The technique is firstly depicted: from a set of simple parameters (paleo-aquifers, infiltration or dissolution zones, conduits characteristics: length, direction, density, and aperture) the incremental porosity and permeabilities associated to karstic processes are calculated directly on the reservoir grid; different typologies of karst can be addressed: "plateau?? karst, hydrothermal karst and island sponge karst. Subsequently, an application to a real field case is addressed with multiple realizations of the fast procedure. The Object 2 reservoir of Kharyaga carbonate oil field, lying 60 km north of the Artic Polar Circle, in Nenets Autonomous Territory was modeled with a multi-phase island karst in agreement with the sedimentological interpretation from cores and borehole images. Several hundred realizations have been performed; each realization is scanned with connectivity computations in order to sort the models regarding relevant criteria (volumes connected to wells). Some recommendations and conclusions are suggested from several experiments on this topic.
In carbonate reservoirs, karst processes are frequently observed; these processes have a clear impact on reservoir flow performances and predictions. This is particularly true for the Object 2 reservoir of Kharyaga field; some pairs of distant wells are connecting extremely fast while other pairs of close wells are not effectively connected. For this reason, it is important to address simultaneously two different objectives:
- the appropriate representation of karst conduits network which controls the connectivity of the reservoir;
- the formalization of a stochastic framework to address uncertainties on global connected volumes and related local heterogeneities location;
In this context (highly heterogenous reservoir with strong impact of heterogeneities location), a multiple realizations approach is relevant and necessary. Using a fast geometrical technique to distribute conduits zones consistently with paleo-aquifers infiltration and outlet regions, it is possible to generate, with reasonable CPU performance, multiple realizations of karst conduits network and their corresponding incremental permeability fields.
|File Size||6 MB||Number of Pages||16|