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.

El Carito-Mulata and Santa Bárbara fields are located in Eastern Venezuela in the MaturÍn sub basin and cover almost 300 km2. The asymmetrical anticline of the reservoirs is the result of different tectonic regimes alternating compressive and extensive periods from the late Cretaceous to the Middle Miocene. The fields are producing 240,000 STB/D and their OOIP is estimated to be around 6.5 MMMSTB. The variation of the vertical fluid distribution is predominant. There is a light oil (condensate) at the top of the structure, black oil at the base and free water at different levels in the reservoirs. This vertical fluid distribution is not well represented in the dynamic simulation model, which increases the uncertainty on any prediction or elaboration of the production plan. The main objectives of this study are the determination of the original fluid contacts and the construction of a fluid model, which takes into account the free water presented in the reservoirs. This model can also define the vertical and lateral extension of the oil fields, indispensable for the reserves estimation. The integration of the different kinds of static and dynamic information of 149 wells was necessary in order to obtain a well-supported fluid distribution model. The analysis of the large number of data allowed defining the geometry of the Tar mat (asphaltene content > 20%), which is folded/faulted according to the structure and considered as a sealed layer in reservoir conditions, with thicknesses ranging between 300 and 500 feet. The irregular Tar mat surface limits the reservoirs and controls the free water levels in the fields. This new fluid distribution model was included at the numerical simulation model matching all the wells information about water or type of oil that has been produced or tested. Introduction An accurate description of the fluid distribution in a reservoir is key to reduce uncertainty in the reserves estimates. The complexity of the stratigraphy, sedimentology, structural and fluid distributions were revealed during the evaluation of the reservoir data for El Carito-Mulata and Santa Bárbara fields. The fluid distribution in these fields indicates the evidence of different properties and a strong variation of those with depth. El Carito-Mulata and Santa Bárbara fields are currently sub-divided into four operating areas: North (MUC-2), Central (MUC-1), West (MUC-3) and South (SBC-10). To keep reservoirs pressure constant to avoid asphaltene precipitation, MUC-1 and MUC-3 are currently submitted under natural gas injection project, MUC-2 undergoes water injection while SBC-10 flows naturally. Free water has been identified at different reservoir depths and this fact has not been represented at the previous fluid distribution model, this represents an inconvenience to match the fluids in the numerical model. An asphaltic crude oil, denominated Tar mat for its physical and chemical properties, has also been identified. The term Tar mat is referred to heavy oil zones with high asphaltene content and well-defined limits presenting a local or regional distribution across different stratigraphic levels and depths. The main characteristic of the Tar mat zone is a minimal asphaltene content of 20% on the C15+ molar fraction [1]. A new model for the fluid distribution was generated for the fields in order to consider the original water-oil contacts, identify limits of the reservoirs and zones with Tar mat. Background The previous fluid distribution model is based on a hydrocarbon column whose composition varies with depth, from gas condensate at the structural top to under saturated black oil down the flanks and at the base of the reservoir. A transition zone from gas condensate to volatile oil exists at approximately -14040 ft sub sea (ss). This model contains a water-oil contact, WOC, at -17300 ft ss in the south flank. Two stratigraphic limits are defined for the proven area in the North flank, one at -16800 ft ss and other one at -17400 ft ss (see Figure 1).

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