A method for inhibiting corrosion of metal surfaces, such as carbon steel tubing, that are in contact with a fluid, such as brine in an oil and gas production fluid containing acid gases (e.g., CO.sub.2 and H.sub.2S) is accomplished by introducing a corrosion-inhibiting blend of two components into the fluid, where blend is glycolipids and quaternized amines, glycolipids and phosphate-containing compounds, quaternized amines and imidazoline-like compounds, quaternized amines and phosphate-containing compounds, or combinations of these blends. Each of the two components of the blends are present in an amount effective to synergistically inhibiting the corrosion of the metal surface when used together.

The present invention relates generally to methods for forming peroxyformic acid, comprising contacting formic acid with hydrogen peroxide. The methods for forming peroxyformic acid can include adding formic acid with a relatively lower concentration of hydrogen peroxide, or adding formic acid to a peroxycarboxylic acid composition or forming composition to react with hydrogen peroxide in the compositions. The present invention also relates to peroxyformic acid formed by the above methods. The present invention further relates to the uses of peroxyformic acid for treating a variety of targets, e.g., target water, including target water used in connection with oil- and gas-field operations. The present invention further relates to methods for reducing or removing H.sub.2S or iron sulfide in the treated water source, improving clarity of the treated water source, or reducing the total dissolved oxygen or corrosion in the treated water source, using peroxyformic acid, including peroxyformic acid generated in situ.

An electrical connection structure includes: a first metal member including copper or a copper alloy, a plated tin layer being formed on at least a portion of the first metal member; a second metal member that is electrically connected or connectable to the first metal member; and a surface treating layer formed on the surface of the first metal member. The surface treating layer is formed by applying a surface treating agent containing base oil and a metal affinity compound having a lipophilic group and an affinity group that has an affinity for metal. The metal affinity compound contains an adduct between an acidic alkyl phosphate ester and an azole compound and an adduct between an acidic alkyl phosphate ester and a metal and/or an organic amine compound.

To provide a surface protective agent composition that suppresses corrosion of members of different kinds of metals close to each other due to corrosion current between the metals of the members, and to provide an electric connection structure and a method for producing an electric connection structure using the same. The surface protective agent composition contains (a) a lubricant base oil; (b) a prescribed amount of at least one compound selected from the group consisting of particular phosphorus compounds and a metal salt or an amine salt thereof; and (c) a prescribed amount of an amide compound, and in the case where the component (b) does not contain the metal salt of the phosphorus compound, the surface protective agent composition further contains (d) a prescribed amount of a salicylate of a particular metal and/or a basic (or perbasic) salt thereof, and the electric connection structure containing a surface protective layer consisting of the surface protective agent composition.

Methods of treating aqueous systems with treatment compositions including non-triazole derivatives of imidazoline and/or amide compounds are provided that are effective to inhibit corrosion of corrodible metal surfaces in the aqueous systems. The non-triazole imidazoline and/or amide compounds show comparable or better corrosion inhibition as compared to conventional triazole corrosion inhibitors, and have low toxicity and good stability in the presence of halogens such as halogen-containing biocides or free chlorine.

Methods of treating aqueous systems with treatment compositions including non-triazole derivatives of imidazoline and/or amide compounds are provided that are effective to inhibit corrosion of corrodible metal surfaces in the aqueous systems. The non-triazole imidazoline and/or amide compounds show comparable or better corrosion inhibition as compared to conventional triazole corrosion inhibitors, and have low toxicity and good stability in the presence of halogens such as halogen-containing biocides or free chlorine.

A method for inhibiting corrosion of a corrodible metal surface that contacts a water stream in a geothermal well system. The method includes introducing into the water stream a corrosion inhibitor composition comprising: (i) a cationic surfactant, such as an imidazoline and/or a fatty amine ethoxylate, and (ii) an anionic surfactant.