Applications and Pitfalls of Stochastically Built Static Model Realizations on Reservoir Characterization and STOIIP Distribution of Clastic Reservoirs of Southern Oman Oil Fields

Raja Mukherjee
Shell, Oman
[email protected]

The oil fields of southern Oman consist mainly of fluvial to glacio-fluvial rocks of Palaeozoic age. The two oil fields that were studied comprise stacked clastic reservoirs with large variation in NTG and scale of heterogeneity. The geological characteristics of these reservoirs posed significant challenges in constructing and selecting static model scenarios for simulation and field development. The static models of A and B oil fields, which have 29 reservoir zones, were constructed using stochastic methods and history-matched. These reservoir models presented unique combinations of properties in terms of GRV, NTG, well density and height of the transition zones. This provided an opportunity for testing the impact of these parameters on stochastic model realizations in terms of facies and oil-in-place distribution. The low- and high-case static model scenarios were constructed following two different methods. In the first, low and high case facies logs were created using different petrophysical cut-offs, and used for building low- and high-case static models. The second method used an automated workflow in Petrel^TM to generate 60 stochastic realizations of each base-case model. The facies distribution and oil-in-place ranges of the static models, from both methods, were analysed and compared. The results were used to optimise the selection of model scenarios for simulation and field development planning.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain