Physical Upgrading of Heavy Crude Oils by the Application of Heat
- J.H. Henderson (Gulf Research and Development Co.) | L. Weber (Gulf Research and Development Co.)
- Document ID
- Petroleum Society of Canada
- Journal of Canadian Petroleum Technology
- Publication Date
- October 1965
- Document Type
- Journal Paper
- 206 - 212
- 1965.Petroleum Society of Canada
- 5.8.5 Oil Sand, Oil Shale, Bitumen, 5.4.10 Microbial Methods, 4.2 Pipelines, Flowlines and Risers, 4.1.5 Processing Equipment, 4.1.9 Heavy Oil Upgrading, 4.1.2 Separation and Treating, 4.3.4 Scale, 2.1.3 Sand/Solids Control
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Subjecting a heavy crude oil to mild thermal cracking conditions effects apermanent and significant reduction in its viscosity and specific gravity.Although all crudes are susceptible to cracking, the temperatures and timesrequired usually exceed those required to crack heavy crudes such as thosefound in the Athabasca tar sands. At temperatures below 1000°F, it has alreadybeen established that cracking of both pure hydrocarbons and petroleum can bedescribed by first-order kinetic equations. To use this fact, a reference mustbe established by which the amount of upgrading or conversion of crudeconstituents can be estimated. This was done by subjecting both the originalcrude and the ‘heat-treated' oil to distillation under identical conditions.The residuum from the distillation of the treated oil was compared to that fromthe original crude to establish the ‘degree of upgrading.'
From such laboratory tests on a variety of crude oils, it has been possibleto estimate the time-temperature history necessary to produce specific degreesof viscosity reduction for each. As a result, it is possible to estimate thefeasibility of utilizing heat in the reservoir to facilitate the production ofheavy oil, or of using heat to facilitate the surface handling of oil alreadyproduced.
The permanent upgrading in physical properties occurs so slowly at 500°Fthat the use of temperatures below this level, as currently practiced withheated pipelines, will effect only a temporary improvement in oil fluidity. Attemperatures in excess of 700°F, coking may present serious operating problemsunless residence times are kept very short.
Crude oils of low API gravity and crude oils having a high pour pointpresent production problems both in and out of the reservoir. To overcomesurface handling problems, the oil industry currently practices extensive andexpensive blending of light oils and LPG with heavy crudes to make them easilyhandled in pipelines and storage facilities. An alternative remedial techniqueinvolves thermal cracking. Thermal cracking, with its attendant lowering ofpour point and viscosity, was used in Russia many years ago to facilitate thepumping of heavy crudes (1). Egloff and Morrell (2) proposed, in 1926, toseverely crack a high-pour-point oil at the wellhead to eliminate the need forpipeline heaters and diluents.
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