The paper describes the synthesis and evaluation of a series of environmentally friendly corrosion inhibitors. These products were designed and synthesized especially to introduce in North Sea oil fields. The two compounds selected, out of more than thirty compounds after initial screening were subjected to a battery of tests (as corrosion inhibitors and as water- soluble low toxic chemicals). Finally, one chemical compound was selected with low toxicity, good corrosion protection, high biodegradability, and with low bioaccumulation.
Governments and industry around the world are realizing that environmentally friendly chemicals ~ are important to our general well being and it is important to replace the toxic chemicals to humans and environment with non- or less toxic chemicals. Green chemistry or environmentally friendly chemistry prevents or reduces the use or production of chemicals that are hazardous to the environment and/or human beings. Green chemists search for ways and means to reduce or eliminate emission, production of waste at the end of a chemical process, the use of toxic solvents and the generation of by-products.
Many oil and gas producing formations yield hydrocarbon, brine, carbon dioxide and/or hydrogen sulfide, which are very corrosive to metal tubing, pumps, casing and other production equipment. Corrosion is high in wells producing brine which contains high levels of dissolved acidic gases such as carbon dioxide or hydrogen sulfide and, inorganic salts or low molecular weight organic acids such as acetic, formic or propionic acid. These chemical ingredients, dissolved in water at elevated temperature, increase the corrosivity of the medium.
Corrosion prevention of metallic surfaces is an important industrial task. When the metallic surfaces are oxidized, it leads to metallic ions that either convert to soluble salts or insoluble metallic oxide or hydroxide, carbonate and sulfides. The oxidation of the metallic surface causes deterioration of that surface and results in scale buildup. Traditionally, the most common way to reduce corrosion is to add a corrosion inhibitor to a corrosive system to preserve metals. 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. The organic inhibitors for corrosion are derived from aliphatic and aromatic amines, polyamines, imidazolines and their salts. The inorganic corrosion inhibitors include chromates, zinc phosphates, and silicate. Although these commercially available corrosion inhibitors eliminate or reduce corrosion on metallic surfaces, they are not very friendly to the environment. Increasingly, operating companies, the government and the public have become concerned about the toxicity and environmental impact of oil field chemicals, especially in offshore applications. In offshore operations such as in North Sea, the environmentally sound chemicals are very important 2. To protect the marine environment, corrosion inhibitors should be non-toxic to fish, plants and organisms and should be biodegradable and reasonably water-soluble. Furthermore, the flash point of the solvent and the solvent-evaporating factor of the chemicals should be considered in designing these inhibitors.
As a supplier of corrosion inhibitors, our focus has been to design corrosion inhibitors with low toxicity to a marine environment. This paper discusses various compounds and their compositions, which are very effective corrosion inhibitors in oil and gas field applications but have less impact on the natural environment.
