| 摘要 |
An insulated double-walled well completion tubing system comprising having an inner tubing, an outer tubing for insertion into a well casing; the inner tubing located within the outer tubing, with the bottom ends of the inner and outer tubings sealed together, an insulation layer in the annular volume between the inner and outer tubings, a wellhead connected to the top end of the outer tubing, a source of heated fluid connected to the wellhead, at least one sealing spacer in the annular space above the insulation layer and below the upper end of the inner tubing, for preventing fluid from passing downward through the annular volume and reaching the insulation, the wellhead enclosing a space of sufficient dimensions to accommodate the upper end of the inner tubing at any temperature thereof. In another embodiment the insulated double-walled tubing string may be a continuous, flexible string installed continuously into a well casing. The system may additionally include a vacuum pump connected to reduce pressure within the annular volume which contains the insulation. Methods for assembling such well completion systems are also disclosed.
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