| 摘要 |
<p>A method for heating a well to thaw out a frozen portion of the well or to protect permafrost surrounding the well from thermal cycling due to variations in production rate from the well. Also, a method for improving the pumpability of fluid which is produced from a well which does or does not pass through a permafrost zone. Further, a method for preventing the formation of hydrates in a gas well which is in or out of permafrost. In this invention, an alternating current is applied to at least one pipe in the well and maintained at a desired voltage level, the frequency of the alternating current is varied and controlled to cause a skin effect and to increase the effective electrical impedance of said pipe, and an electrical return is established from beneath the portion of the well to be heated, e.g., from beneath a permafrost zone. By this method the pipe is uniformly heated on its outer surface throughout the portion of the well to be heated to a temperature which prevents hydrate formation, or reduces the viscosity of liquid produced through the wellbore, or causes thawing of ice, or prevents freezing of water present to eliminate alternate freezing and thawing of the permafrost and sloughing of permafrost due to such thermal cycling.</p> |
