MODELING OF SAND PRODUCTION FROM WELLS ON PRIMARY RECOVERY

Cold Production is a recovery process used in uncemented heavy oil res ervoirs in which sand and oil are produced together under primary cond itions. Sand production is known to be necessary in order to better ac cess heavy oil reservoirs. The production of sand into a casing perfor ation was modelled experimentally using a horizontal sand pack. Heavy oil flowed through the sand and out the orifice at one end of the pack . The pack was scanned using an X-ray CT scanner. A high porosity (53% ) channel (wormhole) was observed to develop in the sand pack above a critical pressure gradient. The sand cut was 44% (by volume) as the wo rmhole was developing. When the wormhole broke through the inlet, the sand cut decreased sharply. CT images taken at this time showed that o nly the loose sand within the wormhole started to be scoured away from the top down. The experimental observations suggest that the high san d cuts (20% to 40%) from wells at the start of cold production are due to the growth of wormholes while the sudden decrease in sand cuts (to 1% - 3%) indicates that the wormholes stopped growing. The residual s and cuts observed in the field are likely due to the scouring of the s and within the wormholes.