The development strategy for a green reservoir with a huge gas resource needs to be evaluated based primarily on the presence or otherwise of a possible economic oil column below this gas cap, as well as on other pertinent reservoir property distributions. The evaluation process requires the integration of all available and credible geoscience and engineering information to help justify and support the correct assessment of key elements and options in the development strategy.

The only well that penetrated this structure encountered a "gas-down-to" (GDT) within the upper reservoir interval. The objective is to assess the possibility of the existence of an oil rim below the GDT and to estimate the depth of a possible GOC and the associated degree of confidence. This assessment needs to be done to support a robust hydrocarbon development strategy and to secure approvals from regulatory authorities.

This paper details the use of 3D seismic attribute analysis and forward seismic modelling combined with static reservoir modelling and scenario management to delineate the fluid contacts and to constrain the inherent uncertainties. The direct hydrocarbon indicator (DHI) observed on the 3D seismic data across the field exhibits an excellent structural fit and yielded a robust fluid contact definition. The use of quantitative seismic amplitude analysis as well as scenario synthetic matches with real seismic data was invaluable in guiding the selection of a feasible development option and securing the necessary approvals.

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