Nonporous liquid impermeable cryogenic barrier

A method for reversibly establishing a nonporous, substantially liquid-impermeable cryogenic barrier extending downward from an elongated surface region of the Earth, said surface region having an axis extending along the long dimension of the surface region, comprising the steps of:

• A. establishing a first array of casings extending downward along a first set of central axes from a corresponding first set of spaced apart locations on said surface region, the first set of locations being generally parallel to the axis of said elongated surface region,
• B. establishing a second array of casings extending downward along a second set of central axes from a corresponding second set of spaced apart locations on said surface region, said second set of locations being substantially parallel to and spaced apart from said first set of locations,
• C. establishing a third array of casings extending downward along a third set of central axes from a corresponding third set of spaced apart locations on said surface region, said third set of locations being between said first and second sets of locations and said third array of casings being between said first and second arrays of casings, and further comprising the sequential steps of:
• A. establishing a flow of heat exchange medium in said casings, including the substeps of:
• i. establishing a flow of refrigerant in the first and second arrays of casings to cool the first and second arrays of casings to a temperature of less than 0 degrees C. to establish cold columnar regions in the Earth extending axially along and radially about the first and second sets of central axes, wherein the refrigerant flow and the positions of the first and second arrays of casings are selected so that adjacent cold columnar regions in respective arrays overlap to establish corresponding first and second continuous cold regions having a temperature of less than 0 degrees C., said first and second cold regions being opposite each other and disposed on respective sides of said third array of casings, and
• ii. establishing a flow of a heat transtar agent in a first selected subset of said third array of casings, whereby regions of the Earth surrounding said third array of casings are at a temperature in excess of 0 degrees C. to establish warm columnar regions in the Earth extending axially along and radially about the third set of central axes, wherein the flow of said heat transfer agent and the positions of the third array of casings and of the first selected subset of said third array of casings are selected so that adjacent warm columnar regions in the third array overlap to establish a corresponding continuous warm region extending between said first and second continuous cold regions,
• B. introducing water into a second selected subset of said third array of casings, wherein at least a portion of the water enters said first and second continuous cold regions and freezes therein to establish frozen regions on respective sides of said continuous warm region, wherein sufficient water is introduced to saturate said continuous warm region with water, and
• C. establishing a flow of refrigerant in said first selected subset of said third array of casings, whereby unfrozen water in the continuous warm region freezes to form a nonporous, substantially liquid-impermeable barrier.