Casing Patch

Abstract

Systems and methods for patching a casing are disclosed. A casing patch has two concentric cylinders and a setting ring having ratcheting teeth that prevent radial contraction and prevent radial expansion. A radially outwardly directed force sets the casing patch at a desired location which seals against the casing and can withstand pressures of up to 20,000 psi. A deployment tool comprising corresponding cones can impart a downward force into the radially outwardly directed force, and can release from the casing patch as desired.

1 . An apparatus, comprising:
 a first element having a generally cylindrical shape, an interior surface, and an exterior surface, the first element having a length sufficient to cover an interior surface of a desired region of a casing within a well;   a second element having a generally cylindrical shape, an interior surface, and an exterior surface, the second element having a length substantially coextensive with the first element, the second element having a smaller radius than the first element such that the second element fits within the first element with the outer surface of the second element contacting the interior surface of the first element;   a setting ring positioned between the first and second elements, the setting ring having a circumferential, ratcheted cut extending around the setting ring's circumference, wherein the ratcheted cut permits circumferential expansion of the setting ring and prevents circumferential contraction of the setting ring;   wherein the first element, second element, and setting rings comprise a patch for the casing;   a deployment tool configured to carry the patch to a desired location in the well and to exert a radially outward force on the patch sufficient to deform the patch onto the casing to seal the casing at the desired location.   
     
     
         2 . The apparatus of  claim 1 , further comprising slips on the exterior surface of the first element. 
     
     
         3 . The apparatus of  claim 1 , further comprising an elastomeric sealing element on the exterior surface of the first element. 
     
     
         4 . The apparatus of  claim 1 , further comprising fold-back shoes on the exterior surface of the first element. 
     
     
         5 . The apparatus of  claim 1  wherein the setting ring comprises a first setting ring, the apparatus further comprising a second setting substantially similar to the first setting ring. 
     
     
         6 . The apparatus of  claim 5  wherein the first and second setting rings are spaced apart sufficiently to surround a desired area of the casing. 
     
     
         7 . The apparatus of  claim 1  wherein the first element is made of a first material and the second element is made of second material, the second material being stiffer than the first material. 
     
     
         8 . The apparatus of  claim 7  wherein the first material has a stiffness of approximately 80 ksi and the second material has a stiffness of approximately 160 ksi. 
     
     
         9 . The apparatus of  claim 1  wherein the deployment tool comprises an inner cone and a corresponding outer cone having slopes configured to transmit a downward force into an outward radial force sufficient to set the setting ring. 
     
     
         10 . The apparatus of  claim 9  wherein at least one of the outer cone and inner cone has slots to permit flexure. 
     
     
         11 . The apparatus of  claim 9  wherein the deployment tool is configured to deliver approximately 75,000 lbs of force to set the setting rings. 
     
     
         12 . The apparatus of  claim 9  wherein the deployment tool is configured to release from the patch and to be pulled out of the well. 
     
     
         13 . The apparatus of  claim 1  wherein the setting ring is situated in a recess, wherein the recess is positioned in either the first element at the interior surface, the second element at the exterior surface, or partially in the first element at the interior surface and the second element at the exterior surface. 
     
     
         14 . A method for sealing a portion of a casing in a well, the method comprising:
 positioning a patch in the well at a desired location, the patch comprising two concentric cylindrical elements and a setting ring, the setting ring comprising an outer ring and an inner ring, wherein the outer ring and inner ring have corresponding ratchet teeth that permit radial expansion and prevent radial contraction;   exerting a setting force onto a deployment tool, wherein the deployment tool is configured to impart the setting force into a radially outward force sufficient to expand the setting ring and the patch in a radially outward direction to seal against the casing at the desired location;   collapsing the deployment tool such that the deployment tool releases from the patch; and   pulling the deployment tool out of the well with the patch secured to the casing.   
     
     
         15 . The method of  claim 14  wherein exerting the setting force comprises exerting 75,000 lbs of force in a downward direction. 
     
     
         16 . The method of  claim 14 , wherein collapsing the deployment tool comprises shearing a shear pin. 
     
     
         17 . The method of  claim 14  wherein the two concentric cylindrical element comprise a first element having a first strength and a second element having a second strength greater than the first strength, and wherein the second element is smaller than the first element and positioned within the first element. 
     
     
         18 . The method of  claim 14 , further comprising setting slips on an exterior surface of the patch. 
     
     
         19 . A casing patch, comprising:
 a first cylinder having a first stiffness and an outer diameter;   a second cylinder having a second stiffness less than the first stiffness, the second cylinder surrounding the first cylinder and having an inner diameter substantially equal to the outer diameter of the first cylinder such that the first and second cylinders are friction fit together, wherein the second cylinder has a recess on an interior surface; and   a setting ring positioned within the recess in the second cylinder, the setting ring having ratcheted teeth that permit radial expansion and prevent radial contraction, wherein applying a setting force causes the setting ring to permanently expand due to the ratcheted teeth and to seal onto a casing in a well.   
     
     
         20 . The casing patch of  claim 19 , further comprising a deployment tool configured to impart a downward force into a radially outward force applied in 360 degrees around a circumference of the deployment tool to set the casing patch, wherein the deployment tool is further configured to release the casing patch and be pulled out of the well.