Cold production of heavy oils

Cold production of some heavy oil sand reservoirs, in Canada and Venezuela, entails production rates much higher than expected from estimates based on conventional theory for radial flow. To explain these unusual high rates, several mechanisms have been mentioned essentially from hydro-dynamic and geomechanical origins. Hydrodynamic pro perties of fluids, partially desaturated during production:foamy oils, bubb les in solution, are more favourable than those in place. Internal erosion in the unconsolidated sand reservoirs can create a network of high-permeability channels, known as "wormholes", drastically enhancing the drainage. This paper is divided into four parts: field observations, laboratory exper iments on foamy oils, numerical modelling of foamy oils, geomechanical effe cts linked to sand production.