Abstract

Numerical reservoir simulation model of a giant carbonate reservoir with thick transition zone has been built and the saturation functions have been generated and tested with different Hysteresis options during full field history match process. In this super giant carbonate reservoir with multi-million active cells and twelve reservoir rock-types, running the full hysteresis option proved prohibitive due to excessive run times, and in many cases the run fails. Therefore scanning curves have been generated using algorithms to mimic the hysteresis option. This paper aims at presenting the impact of using water-oil capillary pressure and relative permeability full Hysteresis for mixed wet super-giant carbonate reservoir on the full field history match results of water flood and development plan for EOR as well as optimizing the 3D simulation run time. Different models were tested including Corey model, modified Corey, and Killough Hysteresis model to develop appropriate bounding and scanning curves. Sector model was built to ensure reliable scanning curves from each model, and the resulting scanning curves from this sector model compared with the mathematical approach used to generate scanning curves over a wide range of water saturation.

Several sensitivities on SCAL Hysteresis option have been made to improve the match quality of the water saturation changes, breakthrough time and production & pressure performance on field and individual wells level (i.e. No Hysteresis, both Kro & Krw Hysteresis, only Kro Hysteresis, full Hysteresis Kr & Pc…. etc.).

Using full Hysteresis saturation function curves show significant impact in the history match quality especially in transition zone where it was difficult to match the flood front with the normal saturation function. It worth mentioning that using scanning curves (121 curves was the optimum number of scanning curves) showed reduction in the simulation run times compared with the full hysteresis option.

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