Reservoir Study V9 of El Furrial Field, Venezuela

Abstract

Abstract El 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 studyshowed 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 optionvalidated 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 recollectionand the reservoir model V9, which is one of the biggest world wide. Introduction "El Furrial" field is located North of Venezuela and was discovered by the well FUL-1 in February 1986 (Fig. 1). The field produces from two main formations identified as the Naricual and Cretaceous Formations. The gross thickness of the two reservoirs is more than 2100 ft. The oil composition in El Furrial Field changes rapidly with depth from conventional oil (28 °API) at the top of the formation to tar, at the base of the reservoir. The initial reservoir pressure was 11,258 psi at 13,800 feet subsea, indicating significant over- pressured conditions, at average reservoir temperature of approximately 300ºF. The porosity ranges of between8–15% and permeability between 60–1200 md. Initially, the production mechanism was natural depletion under rock-fluids expansion. Secondary recovery processes were applied later, flank water injection in Naricual (1992) and then in Los Jabillos (1997). In 1998 crestal miscible gas injection started in Naricual