Abstract: Reservoir Characterization of Fluvial Sandstones for Reservoir Simulation, North Central Africa

DRUMHELLER, RICHARD E; ROBERT P. DANIELS; JEFFREY M. YARUS

The reservoir characterization of fluvial sandstones from the braid-plain environment in north central Africa presents the challenge commonly faced early in the development sequence of petroleum reservoirs: a significant lack of specific local reservoir data.

The essential description of the reservoir necessary for proper production planning includes log and core data from the first few wells, indistinct local seismic information, preliminary production test data, which are complemented by extensive regional but general studies of the sandstones, and by analogy with apparently similar fields elsewhere. The data was incorporated into 3D stochastic models as it became available, and numerous geostatistical realizations were constructed for eventual use in mapping and reservoir simulation studies. The output from the stochastic modeling has proven very useful for all types of reservoir simulation, both 2D and 3D. Local, very detailed extracts of the model provided engineering models the sort of information needed to more correctly simulate reservoir behavior in a compartmentalized, heterogeneous system. The modeling products provided an important influence on initial sets of conventional deterministic geologic maps, constructed for the benefit of production planning, and for an enhanced geological understanding to be applied to local field development and to further exploration in the region.

Geostatistically based stochastic modeling requires and fosters good cooperation and communication among various disciplines: geology, geophysics, petrophysics, reservoir engineering, and production engineering, and has proven to be very useful in the proper description of complicated reservoir systems.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria