The laboratory investigation described arose from a need to observe more directly how sand production can lead to enhanced oil recovery during 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-tomography (CT) X-ray scanner. The experiment showed that (1) stable wormholes can develop in unconsolidated oil sands, (2) they likely develop in the weaker sands (which normally contain the most oil) within a formation, (3) a critical flow rate is required for the wormholes to grow, (4) the high sand cuts observed in the field at the start of cold production indicate that the wormholes are growing, and (5) the decrease in sand production rate observed in the field indicates that the wormholes have stopped developing and are being emptied out by scouring.