Treatment of Drilling Fluid to Combat Corrosion
Authors: Bush H.E. 
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
This paper was prepared for the 49th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Texas, Oct. 6–9, 1974. Permission to copy is restricted to an abstract of not more than 300 words. illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
The primary causes of drilling fluid corrosion are oxygen, hydrogen sulfide and carbon dioxide. Oxygen is considered as the major problem because of its constant availability and problem because of its constant availability and pitting characteristics. Experience in pitting characteristics. Experience in controlling this contaminent has led to the development of practical monitoring methods and treating techniques. This information has been useful in combatting each of the causes of corrosion. Case histories are used as examples of the results of this work.
The field application of methods used to monitor corrosion and treatments made to control corrosion contaminants should be useful in involving current drilling problems.
The control of oxygen in drilling fluid is of major importance in reducing corrosion rates, pitting and downgrading of drilling equipment. pitting and downgrading of drilling equipment. Significant benefits are realized when hydrogen sulfide and carbon dioxide are also controlled.
An uncomplicated corrosion probe permits continuous measurements indicating corrosion problems and appraisal of corrective treatments. problems and appraisal of corrective treatments

Introduction
Corrosion of drill pipe, protective casing strings and other related equipment is recognized as a serious problem that requires control. Historically the industry has been interested in functional methods of controlling corrosion while drilling. Quite often the methods, even though effective, were designed to provide protection to certain portions of the exposed protection to certain portions of the exposed equipment perhaps leaving the rest unprotected. An example of this is internally plastic coated drill pipe. These coatings are functional. where they are properly applied and remain bonded. The protective plastic coatings cover one of the trouble spots, but the external surface of the drill pipe and the internal surface of the casing remains exposed and subject to corrosive failure. Other examples of specific corrosion protection are sealed bearing bits and alloy protection are sealed bearing bits and alloy selection for casing or pressure control equipment. Specific protection of various components is needed, but overall protection is also important. The treatment of drilling fluid to combat corrosion provides the best common medium for overall control.

ECONOMICS
The economics limits for drilling fluid corrosion control is difficult to assess.