Importance of Integrated Reservoir Characterization and Modified Workflow in Modeling a Paralic to Marine Sedimentation Process: Upper Burgan Formation, Raudhatain Field, North Kuwait

Complex reservoir architecture, uneven water movement and diverse depletion patterns in Upper Burgan Formation required building multiple high resolution reservoir models integrating a huge amount of static and dynamic data and eventually selecting the most probable model for flow simulation. Recognition of the main depositional environment and the associated systems is the key to the detailed reservoir description. The Formation consists of low angle deltaic systems with tidally-influenced channels and low energy shoreface environments. A low frequency highstand systems tract has been divided into complex succession high frequency systems tracts. Marine-influenced channels, mouthbars and shoreface sands with differing sand geometry were the modeling targets.

High resolution sequence startigraphy, core and log signatures were used for identifying flooding surfaces and flowunits. Petrophysically derived and core-calibrated facies maps were prepared for each flowunit. Facies belts corresponding to sand bodies were used as input to generate object models. Acoustic impedance from 3D seismic inversion, calibrated to electro-facies, was used to map the channel and interchannel areas. Away from the wells, the seismically derived information constrained the facies belts. Vertical facies trends were estimated from well data with multiple facies. In sand-dominated units, non reservoir was simulated using different probabilities of occurrence: lower probability in major channels than channel abandonment/bay facies. Shape and size of the simulated bodies were varied to match the anticipated 3D facies model. Geostatistics biased to facies models were used for petrophysical models.

Integration of seismic attributes and paleocurrent data for channel depiction, electrofacies and depositional facies maps and object modeling with lateral and vertical facies distribution constraints were useful in depicting the complex sand bodies. A major modification in modeling workflow was the use of multiple facies models after suitable alteration in the gridding and modeling algorithms. The paper describes the integration process leading to describing complex reservoir architecture in detail.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California