This paper presents an exDerimental study on pioelining of Shanjiasi heavy crude oil as oil-in-water emulsions. Viscosity reductions of more than three orders of magnitude were achieved in laboratory by emulsification. Field trials were then made in three 4-in. gathering lines 101, 160 and 241 meters long respectively. A chemical solution was injected into the gathering line at the wellhead. Drag reductions of 40-80% were achieved provided that the formed emulsions had an injected water fraction of 0.2-0.4 and the chemical concentration was at 0.35-0.5% (based on injected water). It was also found that drag reduction was more significant at a low temperature and for a highly viscous heavy oil. A big difference existed between rheologi" cal data obtained from the field trials and those from laboratory experiments, and possible reasons were discussed.