This paper presents the building of a geocellular static model of El Furrial, giant oil field in Venezuela. El Furrial field, located in the north of Monagas state, was discovered in 1986. It originally contained about 7 billion STOIIP. The field is approximately 13 km along strike and 7 km wide. It produces from two reservoirs identified as the Naricual and Los Jabillos Formations. The gross thickness of the two reservoirs is about 2500 ft. The oil composition in the Furrial Field changes rapidly with depth from that of a conventional oil (28 °API) at the top of the formation to that of an immovable tar mat, principally as a result of an increasing alphaltene content of the crude. This full field model is set in highly structural complex reservoir. A new software's chain, RML (Reservoir Modelling Line) was used and has allowed to build an accurate 3D model respecting the most important geological constrains of the field data. Five separated but integrated applications allow to take into account complex structural setting as well as petrophysical data and a high diversity of sedimentological environments which composed the reservoir. Two first applications (GeoSurf and GeoSim) are used to build an accurate structural framework integrating complex surfaces and more than 60 main faults. A new simulation option (Pluri gaussian algorithm) of stochastic application (Heresim) provides a better solution to restore complex channel or bar architecture and to attribute properties parameters. The resulting very high resolution geocellular grid (about 350 million of cells), have been successful up scaled in term of rock type, porosity and permeability with the 2 last applications (SimGrid and SimUp) to obtain a coarse model of about 900 thousand cells to be used in dynamic simulations. Using such a line of applications had permitted to get a very integrated model and to be secure of the existence of a very close link between the resulting static and dynamic models. Introduction El Furrial field is set up in the external foothills of Oriental Basin of Venezuela at NW of Monagas province (Fig. 1). It is located in the state of Monagas, Venezuela, approximately 25 km West of Maturin city, and was discovered by the FUL-1 well in February 1986. This well was completed in the Upper Tertiary Naricual Formation. The initial oil in place (STOIIP) is estimated in the Naricual Formation to be about 7 billion STB. The API gravity for the FUL-1 oil was 28°API. The initial reservoir pressure was 11258 psi at 13800 feet subsea, and at the average reservoir temperature (approximately 300°F), this indicates the reservoir was initially over-pressured. Initially, the production mechanism was natural depletion under rock-fluids expansion. The field produced from two reservoirs identified as the Naricual (Tertiary age) and the Los Jabillos (Cretaceous age) Formations. The gross thickness of the two reservoirs is about 2500 ft. The average porosity is 13% and the average permeability is around 300 md. Today the field has 113 production wells (163 production strings), 44 water injection wells and 7 gas injection wells. Present production rate is about 400 MBOPD. The cumulative production is 1600 MMSTB. The average reservoir pressure is at 6500 psi. A new software solution, RML (Reservoir Modelling Line) is applied to build a full field geocellular model. Using this chain of applications allow to elaborate a very realistic 3D structural model which can be used as a guide to build an accurate high resolution grid. This high resolution grid can then be filled by results from the HERESIM's stochastic application. The two last applications are subsequentially used to define a coarser grid adapted to run dynamic field simulations and for up scaling different parameters of the model respectively.

This paper presents an analysis of the compositional process involved in the displacement of oil by high pressure gas injection as observed in laboratory experiments. Such an analysis is necessary in order to transpose these results to a field-wide scale for EOR projects. Therefore a two-fold compositional tool has been developed: The first function handles the Peng and Robinson equation of state to describe phase equilibria of multicomponent hydrocarbon mixtures. Based on thermodynamic considerations it computes either frontal or rear dynamic miscibility pressure as well as direct miscibility pressure of a gas/oil system.The second function simulates linear displacement of oil by gas involving compositional exchanges between phases (also based on P.R. equation of state) and their effect on flow parameters. Results of this compositional model are checked against laboratory experiments carried out on a field crude oil with three possible injection gases. This model yields a better understanding of various types of non-equilibrium gas drives and enhanced recoveries related to compositional transfers and mobility variations. A useful application is to select the most appropriate gas to be injected into a given field under reservoir conditions or after some depletion. It also shows how the notion of gas/oil relative permeability curves should be reviewed if a black-oil model is used to simulate flow of non-equilibrium fluids.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractEl Furrial field is one of the most important hydrocarbon giants of Venezuela. It's located at the north of the Monagas State and it handles approximated 45 % of the production of this area. It was discovered in 1986 and its characteristic makes it unique. The strategy of development has been supported by the combined injection of miscible gas and water, this has allowed to maintain the production plateau of 400 MBPD. A previous feasibility study showed a recovery factor ranging from 50 % to 60 % by implementing AGA, that study lead to the necessity of a new numeric model capable of simulate non conventional recovery possesses, creating a model known as the V9 Model.This new approach is one of the most transcendental advances of the El Furrial field characterization. It's created over a structural model, which is based in 3D seismic of 370 Km2., which allowed a better definition of structural complexity. A petrophysics supported by 13692' of core, classified by 5 types of rocks, representing the heterogeneity of the reservoir. A high resolution stratigraphics model which is based on a cronostatigraphic criterion, which defined 47 statigraphic units. A sediment model based on 24 Paleoambient maps, considering direction of the sediment in the geostatistic model. A fluid model which changed a TarMat surface that varied from a horizontal to a folded one. A Geocellular model which is described by a 350 million cells grid, which generated a simulation grid of 500K active cells out of 900K.A thermodynamic model which honors the fluid model, with a miscible option validated by a slim tube and iswelling tests and a state equation for the compositional simulation. A rock-fluid model with a set of curves per rock type, which considers the hysteresis process that allowed simulate the AGA and the Dewatering process.As a result the OOIP increased in 1.3 MMMBls. A fluid model with thicker and area extension of the TarMat in the sands. Drilled new delineation wells in areas previously considered in the non-economic limit incorporating new reserves and the development of new opportunities. A portfolio of 70 locations for the development of reserves of the field. Modeling of an AGA pilot project in order to evaluate the implementation of it. Evaluation different injection processes conventional and non conventional, in order to define the development plan of the field. The integrated subserface-surface simulation achieving the integration between recollection and the reservoir model V9, which is one of the biggest world wide.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractEl Furrial field is one of the most important hydrocarbon giants of Venezuela. It's located at the north of the Monagas State and it handles approximated 45 % of the production of this area. It was discovered in 1986 and its characteristic makes it unique. The strategy of development has been supported by the combined injection of miscible gas and water, this has allowed to maintain the production plateau of 400 MBPD. A previous feasibility study showed a recovery factor ranging from 50 % to 60 % by implementing AGA, that study lead to the necessity of a new numeric model capable of simulate non conventional recovery possesses, creating a model known as the V9 Model.This new approach is one of the most transcendental advances of the El Furrial field characterization. It's created over a structural model, which is based in 3D seismic of 370 Km2., which allowed a better definition of structural complexity. A petrophysics supported by 13692' of core, classified by 5 types of rocks, representing the heterogeneity of the reservoir. A high resolution stratigraphics model which is based on a cronostatigraphic criterion, which defined 47 statigraphic units. A sediment model based on 24 Paleoambient maps, considering direction of the sediment in the geostatistic model. A fluid model which changed a TarMat surface that varied from a horizontal to a folded one. A Geocellular model which is described by a 350 million cells grid, which generated a simulation grid of 500K active cells out of 900K.A thermodynamic model which honors the fluid model, with a miscible option validated by a slim tube and iswelling tests and a state equation for the compositional simulation. A rock-fluid model with a set of curves per rock type, which considers the hysteresis process that allowed simulate the AGA and the Dewatering process.As a result the OOIP increased in 1.3 MMMBls. A fluid model with thicker and area extension of the TarMat in the sands. Drilled new delineation wells in areas previously considered in the non-economic limit incorporating new reserves and the development of new opportunities. A portfolio of 70 locations for the development of reserves of the field. Modeling of an AGA pilot project in order to evaluate the implementation of it. Evaluation different injection processes conventional and non conventional, in order to define the development plan of the field. The integrated subserface-surface simulation achieving the integration between recollection and the reservoir model V9, which is one of the biggest world wide.

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