Patent ID: 8104537

Claim:
A method of lowering the temperature of a subsurface formation, comprising: (a) injecting a cooling fluid under pressure into a wellbore, the wellbore being completed at or below a depth of the subsurface formation, and the wellbore having a bore formed through the subsurface formation defining a diameter, wherein the cooling fluid comprises a slurry having particles of frozen material, wherein the wellbore comprises an elongated tubular member, the elongated tubular member comprising a U-tube comprising a downward portion through which the cooling fluid flows to the subsurface formation, an upward portion through which the cooling fluid flows back to the surface, and the downward portion is insulated above the subsurface formation; and (b) circulating the cooling fluid across the formation in order to lower the temperature of at least a portion of the formation to a point that is at or below the freezing point of water.