ABSTRACT

This paper describes the synthesis and evaluation of a series of environmentally friendly corrosion inhibitors. These products are designed and synthesized especially to be introduced in the North Sea oil fields. Four compounds selected out of more than fifty compounds, after initial screenings, were subjected to a battery of tests as corrosion inhibitors and as water-soluble environmentally friendly chemicals. Three of these chemical compounds were selected based on their low toxicity, excellent corrosion protection, good biodegradability, and low bioaccumulation.

INTRODUCTION

Corrosion prevention is a serious and difficult problem in the oil and gas industry and is acute in offshore operations. Corrosion inhibitors are essential as they prevent discharge of oil and/or gas through leakage to the surroundings. Therefore, the use of corrosion inhibitors is important in the oil and gas industry to prevent accidents through leakage. Corrosion inhibitors are water-soluble and/or oil soluble chemical compounds. When added in small quantities to an aggressive medium, these chemicals inhibit corrosion by changing the surface conditions of the metal. Organic corrosion inhibitors for corrosion inhibition are derived from aliphatic and aromatic amines, polyamines, imidazolines and their salts. They usually contain a polar head group and an oil soluble hydrocarbon tail. These corrosion inhibitors are designed to be active in both oil and water phases as surfactants. Polar head groups of this type of inhibitors prefer aqueous phase and non-polar tails prefer the hydrocarbon phase. The polar head groups are attracted to the charged steel surface due to local currents. Non-polar tails may collapse on to the steel surface and prevent the surface contacting water. This effectively cuts off the local current of the electrochemical cell and thus corrosion.

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