The Pipeline Transportation of Heavy Oils

Abstract Heavy oils tend to be highly viscous. The excessive pressure gradientscaused by high viscosity have discouraged the development of heavy oilpipelines in Western Canada. This paper reviews briefly and comments on some ofthe methods used to overcome this difficulty. The crude may be heated to reduce viscosity. This method is well known, andtemperature profiles along a hot oil pipeline may be calculated by an equation given in the paper. There is some difficulty, however, in accurately predictingheat transfer rates because of unknowns in soil temperature andconductivity. Blending the viscous crude with a diluent to reduce its viscosity isprobably the simplest method of obtaining pipeline access to interprovincialmarkets. If a light diluent such as natural gasoline is used, even small percentages greatly reduce the viscosity. Although there are methods ofestimating the viscosity of a blend from a knowledge of the viscosity of the components, laboratory tests on the actual blends to be transported margin moredependable information. The addition of water to viscous oil lines is known to reduce pressuregradients, and research on this matter has been conducted by several people, including the Alberta Research Council. This method, however, may have certain operating difficulties and more work on the matter, would he helpful. The designer of heavy oil pipelines is advised to give careful consideration to all the alternatives and make detailed studies before deciding on the methodto be used. The paper outlines briefly some of the design features of Husky Pipeline Ltd.'s Lloydminster to Hardisty system, which went into operation late in 1963.This 6 5/8-in. pipeline, 72 miles long, utilizes three pumping stations tohandle a blend of Lloydminster crude and natural gasoline. The pumpage isheated to 130°F at each station. A fourth pumping station at the outlet end(Hardisty) allows pumping in either direction; the reversal is used to batchthe diluent north to the crude source, where it is blended with the Lloydminster crude. The blend pumping rate is 15,000 bbls/day.