Methods for controlling temperatures in the environments of gas and oil wells

Abstract

Methods and apparatus are provided for controlling temperatures in the environments of oil, gas condensate, or gas wells. Methods are provided for reducing the melting of glaciers and ice dams through the deployment of hydrate-forming substances. Active methods involve employing a vapor-compression refrigerator/heat pump cycle in an annulus lying between the relatively hot production string and the relatively cold outer pipe. Passive methods include: deploying cold hydrate-forming fluids into the external ice-laden environment of an oil, gas condensate, or gas well in a permafrost area and allowing those hydrate forming fluids to mix with any melt-water that may be present or that may subsequently form due to the loss of heat from the oil, gas condensate, or gas well. Mixtures of the hydrate forming fluids and the melt-water will set up into a solid having a much higher melting point and a much lower thermal conductivity than those of ice.

1 . A method for mitigating the ice melting effects of heat transfer caused by the production of relatively hot fluids from an oil, gas condensate or gas well in a permafrost area, comprising the steps of:
 a. introducing one or more cold hydrate-forming fluids into an external ice-laden environment proximate the well in the area of such heat transfer; and   b. permitting said one or more hydrate forming fluids to mix with any melt-water that may be present in said environment or that may subsequently form in said environment due to the loss of heat from the well so that said mixture of said one or more cold hydrate-forming fluids and melt-water form solid hydrates.   
     
     
         2 . The process of  claim 1  wherein said one or more hydrate-forming fluids are selected from the group consisting of tetrahydrofuran, p-dioxane, CO 2 , H 2 S, and the low-molecular-weight hydrocarbons. 
     
     
         3 . The process of  claim 1  wherein said one or more hydrate-forming fluids include at least one of tetrahydrofuran, p-dioxane, CO 2 , and H 2 S. 
     
     
         4 . A process for reducing ice melt in the vicinity of a glacier, ice dam, or other naturally occurring ice formation comprising the steps of:
 a. locating one or more zones in the vicinity of said glacier, ice dam, or other naturally occurring ice formation where melt-water exists or is likely to exist;   b. introducing at least one cold hydrate-forming fluid into said one or more zones; and   c. permitting said at least one hydrate forming fluid to mix with any melt-water that may be present in said one or more zones or that may subsequently form in said one or more zones so that said mixture of said at least one cold hydrate-forming fluids and melt-water form solid hydrates.   
     
     
         5 . The process of  claim 4  wherein said hydrate-forming fluid is selected from the group consisting of tetrahydrofuran, p-dioxane, CO 2 , H 2 S, and the low-molecular-weight hydrocarbons. 
     
     
         6 . The process of  claim 4  wherein said hydrate-forming fluids include at least one of tetrahydrofuran, p-dioxane, CO 2 , and H 2 S. 
     
     
         7 . An apparatus for collecting liquid formed from condensable or vaporizable materials in a low-pressure-gas-filled or partially evacuated annulus of an oil, gas condensate, or gas well comprising:
 a. an inner tubular member having an exterior wall surface;   b. an outer tubular member axially surrounding said inner tubular member and having an interior wall surface;   c. an annular space created between said inner tubular exterior wall surface and said outer tubular interior wall surface; and   d. one or more weir members attached to said outer tubular interior wall surface, said one or more weir members comprising a bottom end having a floor member, one or more concentrically spaced apart annular wall members attached to said floor member, an open top end, and one or more fluid collection chambers created in the space between said one or more concentrically spaced apart annular wall members, said outer tubular member intended to be installed in said well such that said top end of said weir is oriented in a generally upward direction within said well so that annular liquid formed on said outer tubular member interior wall surface is permitted to flow generally downwardly along said outer tubular member interior wall surface and into said one or more fluid collection chambers.   
     
     
         8 . A method of well thermal management in a low-pressure-gas-filled or partially evacuated annulus of an oil, gas condensate, or gas well comprising the steps of:
 a. placing one or more weirs within said annulus,
 said annulus being generally defined as having an inner tubular member having an exterior wall surface; an outer tubular member axially surrounding said inner tubular member and having an interior wall surface; and an annular space created between said inner tubular exterior wall surface and said outer tubular interior wall surface; 
 said one or more weir members being attached to said outer tubular interior wall surface, said one or more weir members comprising a bottom end having a floor member, one or more concentrically spaced apart annular wall members attached to said floor member, an open top end, and one or more fluid collection chambers created in the space between said one or more concentrically spaced apart annular wall members; 
 said outer tubular member being installed in said well such that said top end of said weir is oriented in a generally upward direction within said well so that annular liquid formed on said outer tubular member interior wall surface is permitted to flow generally downwardly along said outer tubular member interior wall surface and into said one or more fluid collection chambers; and 
   b. collecting and sequestering said formed annular fluid.   
     
     
         9 . The method of  claim 8  wherein said method prevents establishment of an effective heat pipe or thermosyphon. 
     
     
         10 . The method of  claim 8  wherein said method disrupts the patterns of convection in the gas present in said annulus. 
     
     
         11 . An expansion control coupler for use in oilfield annular tubing comprising:
 a. a cylindrical tubing connector body having an exterior surface and an interior surface, a central body section having an upper end and a lower end displaced between two threaded connector sections capable of receiving threaded tubing, and one or more liquid outlet holes proximate said upper end creating a conduit between said connector body interior surface and said connector body exterior surface; and   b. a cylindrical capillary expansion groove insert fitted within said central body section comprising
 i. an outer annular wall member having an outer face and an inner face and an upper end and a lower end; 
 ii. an annular liquid collection dam wall member having an outer dam face and an inner dam face and a dam upper end and dam lower end, said dam being connected at its bottom end to said bottom end of said outer annular wall member such that said annular dam wall member and said outer annular wall member exist in a substantially spaced-apart coaxial relationship; 
 iii. a liquid collection zone created by the space between said annular dam member and said outer annular wall member; 
 iv. a lower groove in said exterior surface of said outer annular wall member its proximate its lower end; 
 v. an upper groove in said exterior surface of said outer annular wall member proximate its upper end; 
 vi. one or more drainage holes in the lower groove to permit fluid communication between said liquid collection zone and said lower groove; and 
 vii. one or more capillary grooves located in said outer face of said outer annular wall member connecting between said lower groove and said upper groove to permit fluid communication between said lower groove and said upper groove; 
   said liquid outlet holes in said central body upper end being positioned to register with said upper groove of said outer annular wall member,   said coupler providing fluid communication between said liquid collection zone and said connector body exterior surface.   
     
     
         12 . A well thermal management system for controlling fluid temperatures in fluids produced in oilfield well production tubing comprising:
 a. a well installation having a production tubing string producing fluids from a desired region of a subsurface formation to the surface;   b. a first annulus tubing section axially surrounding at least a portion of said production tubing string, said first annulus having a top end located at the surface of said well installation and a bottom end located at a desired depth along said tubing string, said first annulus tubing section having an inside tubing wall surface and an outside tubing wall surface;   c. a second annulus tubing section axially surrounding at least a portion of said first annular tubing section to the surface, said second annulus having a top end located at the surface of said well installation and a bottom end located at a desired depth along said first annulus;   d. a refrigeration system having an outlet in fluid communication with said first annulus top end for introducing into said first annulus one or more desired refrigerants at a desired temperature(s) and pressure(s), and an inlet in fluid communication with said second annulus top end;   e. one or more zones for collecting liquid formed on said inside tubing wall surface of said first annulus;   f. one or more expansion control elements creating fluid communication between said first annulus and said second annulus at desired depths to permit the passage of said one or more refrigerants from said first annulus to said second annulus, said one or more expansion control elements being located proximate said one or more liquid collection zones; and   g. conduit for directing fluid flow from said second annulus back to said inlet of said refrigeration system,   
       said first and second annulus and said refrigeration system being tied together as a closed system. 
     
     
         13 . The system of  claim 12  wherein said refrigeration system is selected from the group consisting of: vapor-compression refrigerator/heat pump cycle systems, vapor-absorption systems and gas cycle systems. 
     
     
         14 . The system of  claim 12  wherein said refrigeration system is a vapor-compression refrigerator/heat pump cycle system using a compressor for introducing said one or more desired refrigerants, and further comprising a pressure regulation and monitoring system. 
     
     
         15 . The system of  claim 12  wherein said one or more expansion control elements are selected from the group consisting of thermostatic expansion valves and simple capillary tubes. 
     
     
         16 . The system of  claim 12  wherein a liquid collection zone is defined as the region immediately above said bottom end of said first annulus. 
     
     
         17 . The system of  claim 12  wherein said liquid collection zones further comprise one or more liquid collection systems each comprising a concentric extended lip attached to said first annulus inside tubing wall surface at desired depths and wherein at least one of said one or more expansion control elements is placed in said one or more liquid collection systems to permit passage of fluid collected from said first annulus to said second annulus. 
     
     
         18 . A method for controlling fluid temperatures in fluids being produced to a surface oilfield well installation from production tubing located in desired regions of a subsurface formation comprising the steps of:
 a. providing a first annulus tubing section axially surrounding at least a portion of said production tubing string, said first annulus having a top end located at the surface of said well installation and a bottom end located at a desired depth along said tubing string, said first annulus tubing section having an inside tubing wall surface and an outside tubing wall surface;   b. providing a second annulus tubing section axially surrounding at least a portion of said first annular tubing section to the surface, said second annulus having a top end located at the surface of said well installation and a bottom end located at a desired depth along said first annulus;   c. providing a refrigeration system having an outlet in fluid communication with said first annulus top end for introducing into said first annulus one or more desired refrigerants at a desired temperature(s) and pressure(s), and an inlet in fluid communication with said second annulus top end;   d. providing at desired locations within said first annulus one or more zones for collecting liquid formed on said inside tubing wall surface of said first annulus;   e. providing one or more expansion control elements creating fluid communication between said first annulus and said second annulus at desired depths to permit the passage of said one or more refrigerants from said first annulus to said second annulus, said one or more expansion control elements being located proximate said one or more liquid collection zones;   f. providing conduit for directing fluid flow from said second annulus back to said inlet of said refrigeration system;   g. operating said first and second annulus and said refrigeration system as a closed system;   h. directing a refrigerant vapor into said top end of said first annulus;   i. collecting condensed liquid in said one or more liquid collection zones;   j. directing said collected fluids through said one or more expansion control elements into said second annulus, and   k. directing said fluids in said second annulus back to said inlet of said refrigeration system.   
     
     
         19 . The method of  claim 18  wherein said first annulus is maintained at high temperature and high vapor pressure while substantially simultaneously maintaining said second annulus at low temperature and low vapor pressure. 
     
     
         20 . The method of  claim 18  wherein said refrigeration system is selected from the group consisting of: vapor-compression refrigerator/heat pump cycle systems, vapor-absorption systems and gas cycle systems. 
     
     
         21 . The method of  claim 18  wherein said refrigeration system is a vapor-compression refrigerator/heat pump cycle system using a compressor for introducing said one or more desired refrigerants, and further comprising a pressure regulation and monitoring system. 
     
     
         22 . The method of  claim 18  wherein said one or more expansion control elements are selected from the group consisting of thermostatic expansion valves and simple capillary tubes.