Method for downhole sulfur removal and recovery

Abstract

Sulfur sought to be removed from deposits formed at a subterranean gas producing well are dissolved in a high boiling point relatively pure and low cost non-aqueous solvent. The dissolved sulfur is then removed from the solvent by lowering the temperature of the solution to precipitate the sulfur which is then separated and recovered as a relatively pure product. After additional processing the regenerated solvent is injected back down the well hole to dissolve additional sulfur and reutilized in successive cycles of the process.

1 . A method for removal and recovery of sulfur which may be present when natural gas is produced from sour and other gas wells, comprising: 
 dissolving the sulfur in a high boiling point, relatively pure and low cost non-aqueous solvent selected from one or more members of the group consisting of diphenyl ethers, dibenzyl ethers, terphenyls and alkylated terphenyls, diphenylethanes and alkylated diphenylethanes, and mixtures thereof; removing the sulfur from the solvent by lowering the temperature of the solvent to precipitate the sulfur; and    separating the precipitated sulfur as a relatively pure product.    
   
   
       2 . A method in accordance with  claim 1 , wherein the said solvent has a boiling point of above 290° C. at one atmosphere.  
   
   
       3 . A method in accordance with  claim 1 , wherein the said solvent, following the separation of sulfur therefrom is recirculated to the said wells to dissolve additional sulfur for said removal and recovery.  
   
   
       4 . A method in accordance with  claim 2 , wherein the solvent consists of one or more diphenyl ethers.  
   
   
       5 . A method in accordance with  claim 4 , wherein the said solvent for dissolving the sulfur is injected into a said well at pressures from atmospheric to about 4,000 psi.  
   
   
       6 . A method in accordance with  claim 5 , wherein said pressure is in the range of 2,000 to 4,000 psi.