Estimations of the impact of fault uncertainties on reservoir volumes: a new gOcad tool

Magali Lecour and Pierre Thore and Jean-Claude Dulac. ( 1999 )
in: Proc. $19^{th}$ Gocad Meeting, pages 120-139, ASGA

Abstract

Uncertainties conceming oil field reserve estimations are due to a combination of different factors. Some factors affect the knowledge of reservoir geometry and particularly fault geometry. Traditionally, only one structural model of the field is computed according to the input seismic data and the structural geologist knowledge. If the initial model does not correspond to the real structure, ail further estimations of the reserves may be slanted and have catastrophic impacts during the exploitation of the field. A few methods have already been proposed for studying uncertainties around horizons. However, fault geometries are constrained by more geological rules than horizons. Therefore, such methods may not be applied to faults. In this paper, we propose a new way to model faults, fault networks and associated uncertainties. Our purpose is not to estimate the uncertainties, but to incorporate them in the fault modelling and to simulate a large number of possible fault network geometries in a reasonable amount of time. This method must honor uncertainty estimations, keep geological shapesfor thefault geometries and maintain ail the connectivities inside the 3D earth model (faul(-fault contacts and horizon-fault contacts). The flexibility of the parametric fault object, combined with the simulation methods and the new approach used to build 3D Earth Models [Dulac 99], allowsfor the quick computation of a large number of 3D models according to the given uncertainties. This enables the reservoir engineer to study the impact offault uncertainties on the reservoir volume. Associated with other uncertainty studies, this enables to make decisions for the production of the field.

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    BibTeX Reference

    @inproceedings{RUNKJRM8,
     abstract = { Uncertainties conceming oil field reserve estimations are due to a combination of different factors. Some factors affect the knowledge of reservoir geometry and particularly fault geometry. Traditionally, only one structural model of the field is computed according to the input seismic data and the structural geologist knowledge. If the initial model does not correspond to the real structure, ail further estimations of the reserves may be slanted and have catastrophic impacts
    during the exploitation of the field.
    A few methods have already been proposed for studying uncertainties around horizons. However, fault geometries are constrained by more geological rules than horizons. Therefore, such methods may not be applied to faults. In this paper, we propose a new way to model faults, fault networks and associated uncertainties. Our purpose is not to estimate the uncertainties, but to incorporate them in the fault modelling and to simulate a large number of possible fault network
    geometries in a reasonable amount of time. This method must honor uncertainty estimations, keep geological shapesfor thefault geometries and maintain ail the connectivities inside the 3D earth model (faul(-fault contacts and horizon-fault contacts).
    The flexibility of the parametric fault object, combined with the simulation methods and the new approach used to build 3D Earth Models [Dulac 99], allowsfor the quick computation of a large number of 3D models according to the given uncertainties. This enables the reservoir engineer to study the impact offault uncertainties on the reservoir volume. Associated with other uncertainty studies, this enables to make decisions for the production of the field. },
     author = { Lecour, Magali AND Thore, Pierre AND Dulac, Jean-Claude },
     booktitle = { Proc. $19^{th}$ Gocad Meeting },
     pages = { 120-139 },
     publisher = { ASGA },
     title = { Estimations of the impact of fault uncertainties on reservoir volumes: a new gOcad tool },
     volume = { 19 },
     year = { 1999 }
    }