System for pipeline drying and freezing point suppression

Abstract

Method for dewatering, pressure testing, hydrotreating, suppressing methane hydrate formation and suppressing solution freezing point in pipeline operations have been disclosed, where the solution used in the operations includes an effective amount of a metal formate salt. The metal formate salt solutions have a low viscosity, have a high density, have a low metals corrosivity, are non-volatile, have a low solubility in hydrocarbons, are readily biodegradable, have a low toxicity, are non-hazardous, have a low environmental impact, have a freezing point depression property forming water/formate eutectic point mixtures, and have a water-structuring and water activity modification property.

We claim: 
     
         1 . An improved system for use in conditioning and/or pressure testing pipelines comprising
 an aqueous composition comprising an effective amount of a metal ion formate salt,   where the aqueous composition fills a pipeline or portion thereof pressurized to a desired test pressure and the effective amount is sufficient to reduce an amount of bulk water and/or an amount of residual water in the pipeline below desired amounts and/or to depress a freezing point of the aqueous composition to a temperature below an operating temperature of a pipeline, where the operating temperature of the pipeline is below the freezing point of pure water, and where the aqueous composition is directly discharged into the environment without further processing or treatment.   
     
     
         2 . The system of  claim 1 , wherein the effective amount is sufficient to remove substantially all of the bulk water and residual water in the pipeline. 
     
     
         3 . The system of  claim 1 , wherein the metal ion formate salt is a compound of the formula (HCOO − ) n M n+  and mixtures thereof, where M is a metal ion and n is the valency of the metal ion. 
     
     
         4 . The system of  claim 3 , wherein the metal ion is selected from the group consisting of an alkali metal ion, an alkaline metal ion, a transition metal ion, a lanthanide metal ion, and mixtures thereof. 
     
     
         5 . The system of  claim 4 , wherein the alkali metal ion is selected from the group consisting of Li + , Na + , K + , Rd + , Cs + , and mixtures thereof. 
     
     
         6 . The system of  claim 5 , wherein the alkali metal ion is K + . 
     
     
         7 . The system of  claim 4 , wherein the alkaline metal ion is selected from the group consisting of Mg + , Ca + , Sr 2+ , Ba 2+  and mixtures thereof. 
     
     
         8 . The system of  claim 4 , wherein the transition metal ion is selected from the group consisting of Ti 4+ , Zr 4+ , Hf 4+ , Zn 2+  and mixtures thereof. 
     
     
         9 . The system of  claim 4 , wherein the lanthanide metal ion is selected from the group consisting of La 3+ , Ce 4+ , Nd 3+ , Pr 2+ , Pr 3+ , Pr 4+ , Sm 2+ , Sm 3+ , Dy 2+ , Dy 3+ , and mixtures thereof. 
     
     
         10 . The system of  claim 1 , wherein the effective amount is at least about 5% w/w of metal ion formate salt to water and a saturation solution of the metal ion formate salt in water. 
     
     
         11 . The system of  claim 1 , wherein the effective amount is at least about 25% w/w of metal ion formate salt to water and a saturation solution of the metal ion formate salt in water. 
     
     
         12 . The system of  claim 1 , wherein the effective amount is at least about 45% w/w of metal ion formate salt to water and a saturation solution of the metal ion formate salt in water. 
     
     
         13 . The system of  claim 1 , wherein the effective amount is at least about 65% w/w of metal ion formate salt to water and a saturation solution of the metal ion formate salt in water. 
     
     
         14 . The system of  claim 1 , wherein effective amount comprises a saturated or slightly supersaturated formate composition so that the amount of residual water will dilute the formate concentration into a saturated or sub-saturated formate composition.