| 摘要 |
A method for lowering the temperature of a portion of a subsurface format ion is provided. Preferably, the formation is an oil shale formation. The me thod includes the step of injecting a cooling fluid under pressure into a we llbore, with the wellbore having been completed at or below a depth of the s ubsurface formation. The wellbore has an elongated tubular member for receiv ing the cooling fluid and for conveying it downhole to the subsurface format ion. The wellbore also has an expansion valve in fluid communication with th e tubular member through which the cooling fluid flows. The method then incl udes the steps of injecting a cooling fluid under pressure into the wellbore , and expanding the cooling fluid across the first expansion valve. In this way, the temperature of the cooling fluid is reduced. The temperature of the surrounding formation is likewise reduced through thermal conduction and co nvection.
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