Use of Oxygen Scavengers To Control External Corrosion of Oil-String Casing
- F.W. Schremp (California Research Corp.) | J.F. Chittum (California Research Corp.) | T.S. Arczynski (Standard Oil Co. of California)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- July 1961
- Document Type
- Journal Paper
- 703 - 711
- 1961. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 4.1.2 Separation and Treating, 5.2 Reservoir Fluid Dynamics, 1.14 Casing and Cementing, 2.4.3 Sand/Solids Control, 1.6 Drilling Operations, 4.1.5 Processing Equipment, 4.3.4 Scale, 1.11 Drilling Fluids and Materials, 4.2.3 Materials and Corrosion
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This paper describes a laboratory study of causes of external casing corrosion and the test work that led to the use of oxygen scavengers to prevent this attack. External casing failures are classified as water-line, casing-casing, collar and body failures. A corrosion mechanism based on principles of differential oxygen availability is developed that is consistent with facts known about each kind of failure. The field use of oxygen scavengers is depicted as a direct result of the laboratory study.
A part of the paper is devoted to reporting on the field use of hydrazine to control external casing corrosion. Results of field measurements made over a period of several years are presented as evidence of the effectiveness of the hydrazine treatment. The first conclusion reached is that the use of hydrazine materially reduces the cathodic protection requirements for treated wells. This result is interpreted to mean that a reduction is taking place in the amount of corrosion on the casing. Results indicate also that hydrazine shows its greatest usefulness within the first 12 to 18 months after a well is completed when pitting corrosion is likely to be most active.
According to surveys sponsored by the National Association of Corrosion Engineers, the cost of repairing casing leaks caused by external corrosion may exceed $4 million per year. In addition, well damage and lost production resulting from casing leaks probably costs the petroleum industry an additional $5 to $6 million per year.
Concern about the cost of external casing corrosion led to an extensive laboratory study of factors causing this external corrosion and to the development of a new approach to its prevention. This paper presents a discussion of various causes of external casing corrosion, details of laboratory studies and the results of the field use of an oxygen scavenger in well cementing fluids to prevent the external corrosion of oil-string casing.
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