Thermal Efficiency of a Steam Injection Test Well with Insulated Tubing

摘要

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 ot couplings refluxes in the vented annulus and maintained the caisng temperature constant at 212F at all points. Thus wellbore heat loss was 3 to 6 times higher than expected, the same opposite the highest and lowest quality insulated tubing, and the only 30 to 40% less than bare tubing. Insulated couplings or techniques to eliminate annulus steam refluxing are needed to achieve the potential of insulated tubing. (ERA citation 08:017217)