Instrumentation around a warm oil pipeline buried in permafrost

Abstract

A section of an uninsulated pipeline, 90 ft (27.4 m) long and 2 ft (0.61 m) in diameter, was buried in ice-rich permafrost at the Mackenzie Valley Pipe Line Research Limited Inuvik Test Facility. Oil at 160 degrees F (71 degrees C) was circulated through the pipe from July 1971 to January 1972 causing a thaw bulb to develop around it. Instrumentation was placed around the pipe to measure temperature, settlement, and pore-water pressure. Temperatures near the ground surface and at depth were measured using thermistors as the sensing element. Settlement was monitored by spiral foot gauges and by taking elevations at the ground surface and on rods welded to the pipe. Pore pressures were measured by gas-operated and Casagrande-type piezometers. Selection, fabrication, and installation of this instrumentation are discussed.On a enterr\ue9 un tuyau de pipe-line non isol\ue9 de 90 pieds (27. 4 m) de longueur et de deux pieds (0.61 m) de diam\ue8tre dans du perg\ue9lisol riche en glace au centre d'essais d'Inuvik de la Mackenzie Valley Pipe Line Research Limit\ue9e. On a fait circuler dans le tuyau de l'huile \ue0 160 degr\ue9s F (71 degr\ue9s C) de juillet 1971 \ue0 janvier 1972, ce qui provoqua la formation d'un bulbe de d\ue9gel autour du pipe-line. On a dispos\ue9 des instruments autour du pipe-line afin de mesurer la temp\ue9rature, le tassement et la pression interstitielle. On a mesur\ue9 les temp\ue9ratures pr\ue8s de la surface du sol et en profondeur au moyen de thermistors. On a v\ue9rifi\ue9 le tassement au moyen de jauges \ue0 semelle en spirale ("spiral foot gauge") et en mesurant les niveaux \ue0 la surface du sol et sur les barres soud\ue9es au tuyau. On a mesur\ue9 la pression interstitielle au moyen de pi\ue9zom\ue8tres actionn\ue9s au gaz et de type Casagrande. On examine la question du choix, de la fabrication et de l'installation de ces instruments.Peer reviewed: NoNRC publication: Ye