Thermal recovery methods such as steam injection or in-situ combustion are preferred for heavy oil. In cold environments, wellbore heat losses are significant and limit the applicability of thermal recovery. Therefore, it is essential to insulate the well effectively and economically.Our study focuses primarily on the problem of wells penetrating thick layers of frozen earth (i.e., permafrost). The experimental component determines thermal conductivity versus temperature of nanomaterials fashioned into insulation (socalled black and white silica aerogels that are 90-99.8% air), fiberglass, thermolastic insulation, and carbon fibers. A comparator thermal conductivity apparatus as well as direct measurements using heat flux sensors were developed. A simplistic experimental simulation explored the role of mechanical stress due to thermal cycling.Semianalytical and numerical models were also developed to design a superinsulated well. The models incorporate various composite insulations. Computations include wellbore heat losses, wellbore temperature and the permafrost temperature. Different processes were simulated including an injector well with constant fluid temperature. Well failure/stability is inferred from the rate of thaw front propagation. A key parameter is the insulation thermal conductivity versus temperature that is measured directly.Results show agreement of conductivity with literature values at ambient temperature. Aerogels (0.012-0.025 W/m K) are half as conductive as fiberglass (0.03-0.045 W/m K) and three to four times less conductive than thermolastic insulation and carbon fibers (0.04-0.067 W/m K) for temperatures between 40 and 140 °C. Moreover, aerogels and carbon fibers have good mechanical resistance in comparison to fiberglass. The wellbore heat loss and thaw front propagation model indicates that aerogels alone or aerogels in a composite with more conductive insulation may meet the requirements to avoid well failure, even for very high temperature fluids and over long periods.Thus, alone or in combination with active subcooling of the permafrost, aerogel insulations appear to provide effective thermal isolation to insure well integrity. Although aerogel insulations alone are not as effective as active refrigeration, their moderate cost and their ease of use encourage further investigation.