Abstract

A new oil-soluble, filming amine corrosion inhibitor has been developed specifically to treat both sweet and sour corrosion in downhole applications. Its structure contains no amide groups and, thus, is more chemically and thermally stable than the amidoamine and imidazoline-based products widely used in downhole corrosion treating.

The new inhibitor has been evaluated both in the laboratory using wheel test screening methods and in the field. The field trial comprised an entire battery of 39 sour producers at the McElroy Field near Crane, Texas, and was conducted over a 14-month period. Laboratory data indicate superior film period. Laboratory data indicate superior film persistence of formulations of the new amine at lower persistence of formulations of the new amine at lower concentrations, longer times, and higher temperatures than a commercial corrosion inhibitor currently in wide use throughout the Permian Basin and elsewhere. The average batterywide corrosion rate decreased from 2.5 mpy for the commercial inhibitor to 1.6 mpy for the Chevron Amine-based product. In addition, electrochemical Pair probe measurements on batch-treated wells clearly show the improved film persistence of the new material. persistence of the new material

Introduction

one of the most widely practiced means of mitigating corrosion in oil- and gas-producing wells is chemical treatment with inhibitors containing carboxylic acid salts of organic amines. The majority of organic amines used for this application are amidoamines and imidazolines derived from naturally occurring fatty acids and polyethylene amines. A common feature of these filming amines is the presence of amide and/or amidine groups linking the presence of amide and/or amidine groups linking the polar amine and fatty tail portions of the polar amine and fatty tail portions of the molecule. Hydrolysis of these amide and amidine groups is relatively easy under acidic conditions and is probably the predominant chemical degradation probably the predominant chemical degradation mechanism of the conventional corrosion inhibitors under field use conditions. The hydrolytic instability of imidazoline corrosion inhibitors, in particular, has been well documented.

We have developed a new oil-soluble, filming amine corrosion inhibitor specifically for use in both sweet and sour downhole applications which is derived from nonfatty acid feedstocks. Its structure contains no amide or amidine groups and, thus, is more chemically and thermally stable than amidoamines or imidazolines. This paper describes extensive laboratory and field evaluation of the new amine as a component in traditional corrosion inhibitor formulations. All evaluations were carried out in side-by-side tests with Product B, a commercial inhibitor currently in wide use throughout the Permian Basin and elsewhere. Permian Basin and elsewhere. P. 283

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