Systems and methods for initiating annular obstruction in a subsurface well

Abstract

The present invention is directed to systems and methods for initiating annular obstructions in wells used in, or in support of, enhanced oil recovery operations—particularly enhanced oil recovery (EOR) efforts involving steam injection (e.g., steam flooding). In at least some instances, system and method embodiments of the present invention utilize one or more passively-activated annular obstruction devices (and/or hybrid active/passive devices) for inducing annular obstruction, wherein the associated passive or hybrid activation is at least partially controlled by thermal means such that it can be deemed to be thermally-directed or thermally-controlled. Such thermally-directed passive activation can afford considerably more control over the annular obstruction process and, correspondingly, over the overall steam injection into the formation and associated reservoir—thereby providing more efficient recovery of hydrocarbons.

1 . A system for initiating annular obstruction in a subsurface well, said system comprising:
 a) an at least partially permeable liner string situated within a portion of a wellbore that is at least partially open to a hydrocarbon-bearing formation;   b) a sealed metal chamber disposed about a portion of the at least partially permeable liner string;   c) a material contained within the sealed metal chamber, wherein said material is initially in a condensed state, but which transitions to a gaseous state when heated above a certain threshold temperature; and   d) a means of heating the material contained within the metal chamber so as to effect its transition to the gaseous state where, upon transitioning to a gas, the material increases the pressure within the chamber, and where, upon experiencing a pressure increase, the metal chamber expands in such a way as to engage the formation, thereby forming an annular obstruction between the at least partially permeable liner string and the formation.   
     
     
         2 . The system of  claim 1 , wherein the subsurface well is a steam injection well for initiating annular obstruction in a subsurface well. 
     
     
         3 . The system of  claim 1 , wherein the at least partially permeable liner string comprises pores of a type selected from the group consisting of pre-drilled holes, slots, screens, and combinations thereof. 
     
     
         4 . The system of  claim 1 , wherein the sealed metal chamber is selected from the group consisting of: a) an integral part of the liner pipe making up at least part of the at least partially permeable liner string, or b) an attachment affixed to the at least partially permeable liner string. 
     
     
         5 . The system of  claim 1 , wherein the sealed metal chamber has a geometry configured to enhance its ability to engage the formation upon expanding. 
     
     
         6 . The system of  claim 1 , wherein the sealed metal chamber comprises at least one relief valve designed to vent below the burst pressure of said chamber. 
     
     
         7 . The system of  claim 1 , wherein the sealed metal chamber comprises a volume, in the unexpanded state, of from at least about 50 cubic inches to at most about 12,000 cubic inches; and wherein the material inside the sealed metal chamber, upon transitioning to a gaseous state, increases the volume of the sealed metal chamber by at least 50 percent. 
     
     
         8 . The system of  claim 1 , wherein the material inside the sealed metal chamber is, in its condensed state, in a form selected from the group consisting of liquid, solid, and any mixture thereof; and wherein the material inside the sealed metal chamber is selected from the group consisting of water, alcohols, glycols, glycerine, acrylic, polyvinylidene, and combinations thereof. 
     
     
         9 . The system of  claim 1 , wherein the annular obstruction reduces flow in the annulus by at least about 20 percent to at most about 100 percent. 
     
     
         10 . The system of  claim 1 , wherein the means of heating the condensed material comprises introduction of a downhole heat source. 
     
     
         11 . The system of  claim 1 , wherein the meaning of heating involves injection of a heated fluid into the well. 
     
     
         12 . The system of  claim 11 , wherein the means of heating the condensed material involves the injection of steam into the well. 
     
     
         13 . The system of  claim 1 , further comprising one or more additional sealed metal chambers filled with the condensed material, so as to effect multiple annular obstructions in the wellbore. 
     
     
         14 . A method for initiating annular obstruction in a subsurface well, said method comprising:
 a) fabricating a modified length of at least partially permeable liner string, the modified length comprising:
 i) a sealed metal chamber disposed about the modified length of at least partially permeable liner string; and 
 ii) a material situated inside the sealed metal chamber, wherein said material is initially in a condensed state and which transitions to a gas when heated above a certain threshold temperature; 
   b) positioning the modified length of at least partially permeable liner string in an at least partially open hole region of a wellbore, wherein an annular region is established between the modified length of permeable liner string and the open hole region of the wellbore; and   c) heating the modified length of liner string so as to effect a transition of the material contained therein from a condensed state to a gaseous state, where upon transitioning to a gas, the material increases the pressure within the sealed metal chamber, and where upon experiencing a pressure increase the sealed metal chamber expands in such a way as to engage the formation, thereby forming an annular obstruction between the modified length of liner string and the formation.   
     
     
         15 . The method of  claim 14 , wherein the subsurface well is a steam injection well. 
     
     
         16 . The method of  claim 14 , wherein the at least partially permeable liner string comprises pores of a type selected from the group consisting of pre-drilled holes, slots, screens, and combinations thereof. 
     
     
         17 . The method of  claim 14 , wherein the sealed metal chamber is selected from the group consisting of: a) an integral part of the liner pipe making up at least part of the at least partially permeable liner string, or b) an attachment affixed to the at least partially permeable liner string. 
     
     
         18 . The method of  claim 14 , wherein the sealed metal chamber has a geometry configured so as to enhance its ability to engage the formation upon expanding. 
     
     
         19 . The method of  claim 14 , wherein the sealed metal chamber comprises at least one relief valve designed to vent below the burst pressure of said chamber. 
     
     
         20 . The method of  claim 14 , wherein the sealed metal chamber comprises a volume, in the unexpanded state, of from at least about 50 cubic inches to at most about 12,000 cubic inches; and wherein the sealed metal chamber, upon transitioning to a gaseous state, increases the volume of the sealed metal chamber by at least 50 percent. 
     
     
         21 . The method of  claim 14 , wherein the material situated inside the sealed metal chamber is, in its condensed state, in a form selected from the group consisting of liquid, solid, and any mixture thereof; and wherein the material situated inside the sealed metal chamber is selected from the group consisting of water, alcohols, glycols, glycerin, phase change materials, eutectics, and combinations thereof. 
     
     
         22 . The method of  claim 14 , wherein the annular obstruction reduces flow in the annulus from at least about 20 percent to at most about 100 percent. 
     
     
         23 . The method of  claim 14 , wherein the means of heating the condensed material involves injection of a heated fluid into the well. 
     
     
         24 . The method of  claim 23 , wherein the means of heating the condensed material involves injecting steam into the well. 
     
     
         25 . The method of  claim 14 , further comprising the use of multiple modified lengths of at least partially permeable liner string, so as to effect multiple annular obstructions in multiple regions of the wellbore.