Method and apparatus for removing water from a natural gas well

Abstract

Water is removed from a natural gas well by the use of nitrogen, which is produced by a non-cryogenic unit at the site of the well. A cylindrical casing is positioned over the well. A tubing, disposed within the casing, is aligned over the well bore. Nitrogen is selectively introduced into either the space between the tubing and the casing, or into the tubing, so as to displace water from within the tubing or the casing, respectively. The water is directed to a storage tank at the site of the well. Nitrogen is purged from the lines, and the well is ready to resume production.

1 . A method of removing water from a natural gas well, the well including a casing inserted into and extending above a well bore, the casing including a tubing disposed within the casing, the method comprising:
 a) directing nitrogen into an interior of the tubing, while maintaining pressure in the casing, so as to force water out of the casing, and conducting said water into a storage tank,   b) directing nitrogen into a region between the casing and the tubing, while maintaining pressure in the tubing, so as to force water out of the tubing, and conducting said water into a storage tank, and   c) purging nitrogen from the casing and the tubing.   
     
     
         2 . The method of  claim 1 , wherein step (a) is preceded by the step of pressurizing the casing. 
     
     
         3 . The method of  claim 1 , wherein steps (a) and (b) include operating a membrane-based unit for producing nitrogen, and directing said nitrogen into one of the interior of the tubing or the region between the casing and the tubing. 
     
     
         4 . The method of  claim 3 , wherein step (c) comprises interrupting a flow of nitrogen into the casing, and allowing natural gas to flow out of the well, so as to remove residual nitrogen from the casing and the tubing. 
     
     
         5 . A method of removing water from a natural gas well, comprising:
 a) non-cryogenically producing nitrogen at a site of a natural gas well, and   b) directing said nitrogen into a casing located at the site of the well so as to displace water from the well.   
     
     
         6 . The method of  claim 5 , wherein step (b) comprises selectively directing said nitrogen into a tubing located within the casing, or into a space between the tubing and the casing. 
     
     
         7 . The method of  claim 5 , further comprising directing said water into a storage tank located at the site of the well. 
     
     
         8 . The method of  claim 7 , further comprising purging nitrogen from conduits at the site of the well and then resuming production of the well. 
     
     
         9 . Apparatus for removing water from a natural gas well, comprising:
 a) a non-cryogenic unit for producing nitrogen, the nitrogen-producing unit being located at a site of a natural gas well,   b) a generally cylindrical casing positioned over the well and above ground level,   c) a generally cylindrical tubing positioned inside the casing, and being aligned with a bore of the well,   d) conduit means for selectively directing nitrogen from the nitrogen-producing unit to either a region between the casing and the tubing, or to a region within the tubing, and   e) means for conveying water displaced from the well to a storage tank located at the site of the well.   
     
     
         10 . The apparatus of  claim 9 , further comprising a separation unit for removing water from a product natural gas stream, the separation unit being connected to receive natural gas produced by the well. 
     
     
         11 . The apparatus of  claim 10 , wherein the nitrogen-producing unit comprises a polymeric membrane for separation of air into components. 
     
     
         12 . The apparatus of  claim 11 , further comprising a conduit for directing water from the water separation unit to the storage tank.