FULL FIELD RESERVOIR DESCRIPTION AND NUMERICAL SIMULATION OF AURORA OIL RESERVOIR, NORTH SLOPE OF ALASKA

The Aurora reservoir is a satellite of the giant Prudhoe Bay Field. The field currently produces ~9,000 bopd from lower shoreface sands of the Cretaceous Kuparuk River Formation. Production started in 1999. Integrated geological, geophysical petrophysical and reservoir engineering studies were recently completed for Aurora. The studies used seismic, core, log, fluid property, well test, and production data from appraisal and development wells for reservoir analysis, building a full field geocellular model, and simulating reservoir performance.

The subsurface challenges involve building a representative reservoir model on a fine scale to represent a very heterogeneous system. Complex stratigraphy, severe faulting and reservoir compartmentalization, variable fluid contacts, and significant variation in pay thickness and mineralogy make reservoir modeling very challenging. These challenges were overcome by: 1. using a fine scale grid (250' X 250' X 1~2') to model the large number of faults (throws range from 10' to 250'), 2. representing each flow unit as a zone, and 3. using hybrid modeling techniques (object and pixel based) to capture the heterogeneity of each zone. The model is calibrated using the short Aurora production history and then used to develop an optimal reservoir management strategy including tertiary recovery optimization and flood pattern conformance.

This paper discusses the challenges of selecting suitable modeling methodologies, of matching the limited production history, and conducting production optimization forecasts for the geologically complex Aurora Field on Alaska's North Slope.