Storing Hazardous Material in a Subterranean Formation

Abstract

A hazardous material storage bank includes a wellbore extending into the Earth and including an entry at least proximate a terranean surface, the wellbore including a substantially vertical portion, a transition portion, and a substantially horizontal portion; a storage area coupled to the substantially horizontal portion of the well bore, the storage area within or below a shale formation, the storage area vertically isolated, by the shale formation, from a subterranean zone that includes mobile water; a storage container positioned in the storage area, the storage container sized to fit from the wellbore entry through the substantially vertical, the transition, and the substantially horizontal portions of the wellbore, and into the storage area, the storage container including an inner cavity sized enclose hazardous material; and a seal positioned in the wellbore, the seal isolating the storage portion of the wellbore from the entry of the wellbore.

1 . A hazardous material storage bank, comprising:
 a wellbore extending into the Earth and comprising an entry at least proximate a terranean surface, the wellbore comprising a substantially vertical portion, a transition portion, and a substantially horizontal portion;   a storage area coupled to the substantially horizontal portion of the well bore, the storage area within or below a shale formation, the storage area vertically isolated, by the shale formation, from a subterranean zone that comprises mobile water;   a storage container positioned in the storage area, the storage container sized to fit from the wellbore entry through the substantially vertical, the transition, and the substantially horizontal portions of the wellbore, and into the storage area, the storage container comprising an inner cavity sized to enclose hazardous material; and   a seal positioned in the wellbore, the seal isolating the storage portion of the wellbore from the entry of the wellbore.   
     
     
         2 . The hazardous material storage bank of  claim 1 , wherein the storage area is formed below the shale formation and is vertically isolated from the subterranean zone that comprises mobile water by the shale formation. 
     
     
         3 . The hazardous material storage bank of  claim 1 , wherein the storage area is formed within the shale formation, and is vertically isolated from the subterranean zone that comprises mobile water by at least a portion of the shale formation. 
     
     
         4 . The hazardous material storage bank of  claim 1 , wherein the shale formation comprises a permeability of less than about 0.001 millidarcys. 
     
     
         5 . The hazardous material storage bank of  claim 1 , wherein the shale formation comprises a brittleness of less than about 10, where brittleness comprises a ratio of compressive stress of the shale formation to tensile strength of the shale formation. 
     
     
         6 . The hazardous material storage bank of  claim 1 , wherein the shale formation comprises a thickness proximate the storage area of at least about 100 feet. 
     
     
         7 . The hazardous material storage bank of  claim 1 , wherein the shale formation comprises a thickness proximate the storage area that inhibits diffusion of the hazardous material that escapes the storage container through the shale formation for an amount of time that is a multiple of a half-life of a radioactive component of the hazardous material. 
     
     
         8 . The hazardous material storage bank of  claim 1 , wherein the shale formation comprises about 20 to 30% weight of clay or about 20 to 30% weight of organic matter. 
     
     
         9 . The hazardous material storage bank of  claim 1 , wherein the hazardous material comprises spent nuclear fuel. 
     
     
         10 . The hazardous material storage bank of  claim 1 , further comprising at least one casing assembly that extends from at or proximate the terranean surface, through the wellbore, and into the storage area. 
     
     
         11 . The hazardous material storage bank of  claim 1 , wherein the storage container comprises a connecting portion configured to couple to at least one of a downhole tool string or another storage container. 
     
     
         12 . A method for storing hazardous material, comprising:
 moving a storage container through an entry of a wellbore that extends into a terranean surface, the entry at least proximate the terranean surface, the storage container comprising an inner cavity sized to enclose hazardous material;   moving the storage container through the wellbore that comprises a substantially vertical portion, a transition portion, and a substantially horizontal portion, the storage container sized to fit from the wellbore entry through the substantially vertical, the transition, and the substantially horizontal portions of the wellbore;   moving the storage container into a storage area that is coupled to the substantially horizontal portion of the well bore, the storage area located within or below a shale formation and vertically isolated, by the shale formation, from a subterranean zone that comprises mobile water; and   forming a seal in the wellbore that isolates the storage portion of the wellbore from the entry of the wellbore.   
     
     
         13 . The method of  claim 12 , wherein the storage area is formed below the shale formation and is vertically isolated from the subterranean zone that comprises mobile water by the shale formation. 
     
     
         14 . The method of  claim 12 , wherein the storage area is formed within the shale formation, and is vertically isolated from the subterranean zone that comprises mobile water by at least a portion of the shale formation. 
     
     
         15 . The method of  claim 12 , wherein the shale formation comprises geological properties comprising two or more of:
 a permeability of less than about 0.001 millidarcys;   a brittleness of less than about 10, where brittleness comprises a ratio of compressive stress of the shale formation to tensile strength of the shale formation;   a thickness proximate the storage area of at least about 100 feet; or about 20 to 30% weight of organic material or about 20 to 30% weight of clay.   
     
     
         16 . The method of  claim 12 , wherein the hazardous material comprises spent nuclear fuel. 
     
     
         17 . The method of  claim 12 , wherein the wellbore further comprises at least one casing that extends from at or proximate the terranean surface, through the wellbore, and into the storage area. 
     
     
         18 . The method of  claim 12 , further comprising:
 prior to moving the storage container through the entry of the wellbore that extends into the terranean surface, forming the wellbore from the terranean surface to the shale formation.   
     
     
         19 . The method of  claim 18 , further comprising installing a casing in the wellbore that extends from at or proximate the terranean surface, through the wellbore, and into the storage area. 
     
     
         20 . The method of  claim 19 , further comprising cementing the casing to the wellbore. 
     
     
         21 . The method of  claim 18 , further comprising, subsequent to forming the wellbore, producing hydrocarbon fluid from the shale formation, through the wellbore, and to the terranean surface. 
     
     
         22 . The method of  claim 12 , further comprising:
 removing the seal from the wellbore; and   retrieving the storage container from the storage area to the terranean surface.   
     
     
         23 . The method of  claim 12 , further comprising:
 monitoring at least one variable associated with the storage container from a sensor positioned proximate the storage area; and   recording the monitored variable at the terranean surface.   
     
     
         24 . The method of  claim 23 , wherein the monitored variable comprises at least one of radiation level, temperature, pressure, presence of oxygen, presence of water vapor, presence of liquid water, acidity, or seismic activity. 
     
     
         25 . The method of  claim 23 , further comprising, based on the monitored variable exceeding a threshold value:
 removing the seal from the wellbore; and   retrieving the storage container from the storage area to the terranean surface.   
     
     
         26 . A spent nuclear fuel storage system, comprising:
 a directional wellbore formed from a terranean surface, through a first subterranean layer, and into a second subterranean layer deeper than the first subterranean layer, the first subterranean layer comprising a rock formation that includes a source of mobile water, the second subterranean layer comprising a shale formation that fluidly isolates a portion of the directional wellbore formed within the shale formation from the first subterranean layer;   a container configured to be moved through the directional wellbore into the portion of the directional wellbore formed within the shale formation, the container comprising a volume enclosed by a housing configured to store a plurality of spent nuclear fuel pellets; and   a plug set in the directional wellbore between the portion of the directional wellbore formed within the shale formation and the terranean surface.   
     
     
         27 . The spent nuclear fuel storage system of  claim 26 , further comprising a monitoring system, comprising a monitoring control system communicably coupled to one or more systems positioned proximate the container. 
     
     
         28 . The spent nuclear fuel storage system of  claim 26 , further comprising a tubular liner constructed in the directional wellbore and sealed against a wall of the directional wellbore. 
     
     
         29 . The hazardous material storage bank of  claim 1 , wherein the shale formation is at a true vertical depth of between 3000 and 12,000 feet. 
     
     
         30 . The hazardous material storage bank of  claim 9 , wherein the shale formation comprises a diffusion barrier to a radioactive isotope of the spent nuclear fuel. 
     
     
         31 . The hazardous material storage bank of  claim 30 , wherein the radioactive isotope comprises a radioactive gas. 
     
     
         32 . The hazardous material storage bank of  claim 31 , wherein the radioactive gas comprises tritium. 
     
     
         33 . The hazardous material storage bank of  claim 31 , wherein the diffusion barrier comprises a diffusion time of the radioactive gas of the spent nuclear fuel of a multiple of a half-life of the radioactive gas. 
     
     
         34 . The hazardous material storage bank of  claim 33 , wherein the multiple is between thirty and fifty times the half-life of the radioactive gas.