A field test of bare 2.375-in and insulated 4.500-in tubulars has been conducted using heat flux sensors and thermocouples to evaluate bare and insulated tubular performance, annulus heat transfer, and overall wellbore heat loss in a cooperative effort between Sandia National Laboratories and Husky Oil Operations, Ltd. The well is part of a steam flood pilot in the Aberfeldy Field near Lloydminster, Saskatchewan. Insulation thermal conductivity was observed to vary by a factor of four between competing designs. Couplings and internal structures (e.g., centralizers) were seen to account for up to half the string heat loss with the annulus dry. For a wet annulus, the typical field case, steam generated at the hot couplings refluxed in the vented annulus and maintained the casing temperature constant at 212F at all points. Thus wellbore heat loss was 3-6 times higher than expected, the same opposite the highest and lowest quality insulated tubing, and only 30-40 percent less than bare tubing. Insulated couplings or techniques to eliminate annulus steam refluxing are needed to achieve the potential of insulated tubing.

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of bare 2.375-in ar tubulars has been conducted rs and thermocouples to ev tubular performance, annulas heat transfer fer, a overall wellbore heat loss in a coopera-tive effort between Sandia National Laboratories and Husky oil Operations, Ltd. The well is part of a steam flood pilot in the Aberfeldy Field near Lloydminster, Saskatchewan.Insulation thermal conductivity was observes to vary by a factor of four between competing designs. Couplings and internal structures (e.g., centraliz-ers) were seen to account for up to half the string heat loss with the annulus dry. For a wet annulus, the typical field case, steam generated at the hot couplings refluxed in the vented annulus and main-tained the casing temperature constant at 212F at all Points. Thus wellbore heat loss was 3-6 times higher than expected, the saine opposite the highest and lowest quality insulated tubing, and only 30-40 percent less than bare tubing. Department of Energy 76DPOO789. tting-in the annulus increased the pari e and temperature of the steam in the z reased the wellbore heat loss-Heat 1( hut-in annulus with steam and nitrogen times higher than for the wet, vented Ius (15-30 times higher than for a dry annulus and the most effective insulated tubing). Operating the well with the annulus shut-in and filled with liquid water and boiling at the couplings increased the casing temperature and heat loss still further.

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