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U.S. Department of Energy
Office of Scientific and Technical Information

Simulation of permafrost thaw behavior at Prudhoe Bay

Conference ·
OSTI ID:7214365
Drilling and production operations at Prudhoe Bay cause thawing of the permafrost that is present to approximately 1850 feet below the ground surface. When wells are shut in, the thawed zone in the permafrost begins to refreeze. An understanding of heat transfer effects in the wellbore and in the permafrost during drilling, production and freezeback is required for proper design both of casing strings and of the surface facilities that will process the produced fluids. Equations are presented for transient heat flow within a wellbore and the formation around it. The computational scheme employs a finite difference representation of the flowing stream (a mixture of oil, gas and water) together with a variational method which follows two dimensional, unsteady-state heat conduction with a change of phase in the permafrost. Calculated temperatures agree well with measurements taken both in the wellbore and in the permafrost during field tests at Prudhoe Bay. Production-thaw predictions are presented for a typical Prudhoe well with three different insulation methods.
OSTI ID:
7214365
Report Number(s):
CONF-761008-67
Country of Publication:
United States
Language:
English