SIMULATION OF COLD PRODUCTION IN HEAVY-OIL RESERVOIRS - WORMHOLE DYNAMICS

The laboratory investigation described arose from a need to observe mo re directly how sand production can lead to enhanced oil recovery duri ng the cold-production process. The production of oil and sand into a perforation was simulated by use of a sandpack with an orifice at one end. The pack was imaged throughout the experiment with a computed-tom ography (CT) X-ray scanner. The experiment showed that (1) stable worm holes can develop in unconsolidated oil sands, (2) they likely develop in the weaker sands (which normally contain the most oil) within a fo rmation, (3) a critical flow rate is required for the wormholes to gro w, (4) the high sand cuts observed in the field at the start of cold p roduction indicate that the wormholes are growing, and (5) the decreas e in sand production rate observed in the field indicates that the wor mholes have stopped developing and are being emptied out by scouring.