Hydrocarbon reservoir management of a mature reservoir is a complex process of deciphering the reservoir character, through dynamic static data integration, to produce an ideal depletion strategy for the field. A great result is normally a winning opportunity set or strategy defined by a marriage of maximum hydrocarbon recovery with fantastic economic indicators. Is it any wonder we invest heavily into tools and processes to achieve just this!

This paper will explore the use of structural and reservoir modeling tools and techniques to re-design an optimal depletion strategy for an oil and gas reservoir, in a predominantly gas field, in the Columbus basin off the East coast of Trinidad. This reservoir is a massive ~700 ft sand incorporating a 30~40ft thin oil rim with an underlying aquifer and overlain by a huge gas cap. Both oil and gas has been produced from this reservoir since 1998 by 8 oil wells and 4 gas wells spread across two fields.

Should the future of this reservoir first rely on targeting remaining oil or do we shift into high gas acceleration gear? To solve this conundrum all subsurface hands were brought on deck. The formulation of an appropriate depletion plan requires a multi pronged approach, as a clear alliance must be made between business objectives, reducing risk and good reservoir management practice.

A VIP/Nexus reservoir simulation model was the ‘tool of choice’ to investigate which depletion direction to forge ahead with. The first stage of this reservoir management investigation was the creation of a reliable structural model which then acted as the foundation for the build of a representative reservoir model. As part of this paper’s journey, we delve into the process flow used to mimic this magnificent reservoir. We endeavor to deepen your understanding of, the application of crucial petrophysical modeling in the reservoir characterization procedure and the unmistakable impact of history matching over 12 years of production and pressure data. The result of this work was a fit for purpose reservoir model enabling the operator to make the right decisions for future development of this reservoir.

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