|Content Type||Conference Paper|
|Title||Testing Methods and Standards for Oilfield Corrosion Inhibitors|
|Authors||Sankara Papavinasam, R. Winston Revie, CANMET Materials Technology Lab; Milan Bartos, Nalco|
|Source||CORROSION 2004, March 28 - April 1, 2004 , New Orleans, La|
|Copyright||2004. NACE International|
|Keywords||inhibition, corrosion inhibitor, pipeline, oil field, rotating disc, rotating cylinder, rotating cage, jet impingement, ranking, pitting corrosion, sweet, sour, wheel test, bubble tests, RDE, RCE, JI.|
Laboratory methodologies to evaluate corrosion inhibitors for oil field application are reviewed in this paper. The importance of establishing the factors that control the hydrodynamic parameters in the laboratory methodologies is described. The reasons for developing standards on laboratory methodologies for evaluating corrosion inhibitors are outlined.
The corrosion of oil and gas pipelines results, in part, from the use of carbon and low-alloy steels in pipeline construction. Although cost-effective, these steels exhibit poor corrosion resistance under some conditions. Corrosion inhibitors are used to control internal corrosion in upstream pipelines carrying oil and gas from fields to processing plants; however, no single inhibitor suits all situations. The effectiveness of an inhibitor is determined not only by the properties of the gas and liquid contents of the pipeline and by the properties of the inhibitor itself, but also by the way it is added to the pipeline and the operating conditions of the system (temperature, flow rate, and pressure).
Because of the complexity involved in evaluating corrosion inhibitors, the availability of sophisticated methodologies to evaluate inhibitors, the cost associated with screening and using inhibitors to control internal corrosion of pipelines, the widespread use of inhibitors, and to manage risk where public safety is involved, it is important to standardize the methodologies that are used to evaluate and qualify inhibitors. Any laboratory methodology that is being considered for the evaluation of inhibitor performance in a particular system should itself be assessed for the effectiveness with which the significant variables can be simulated. In this paper, the laboratory methodologies to evaluate corrosion inhibitors for oil field application are reviewed. The importance of establishing the factors that influence the hydrodynamic parameters of the laboratory methodologies is presented. The need to develop standardized procedures for the laboratory methodologies to evaluate corrosion inhibitors is identified.
LABORATORY METHODOLOGIES FOR EVALUATING CORROSION INHIBITORS
The Working Party on Inhibitors of the European Federation of Corrosion has produced a state-of-the-art report on laboratory methodologies for inhibitor evaluation . The methodologies for evaluating inhibitors in oil and gas technologies, e.g., in production, transmission, and storage, often requires the use of two phase oil-water fluids, in addition to the corrosive gas. The methodologies described in the report are based on rotating probes in autoclave, wheel, and bubble tests.
Recognizing that it may not be necessary to control all the parameters in laboratory tests that are intended for screening, evaluation and selection of inhibitors, it is reported that inhibitors selected based on the wheel test and kettle test (linear polarization resistance [LPR]) in the laboratory performed consistently well in pipeline and downhole tubular applications in the field .
Garber et al.  tested several gravimetric and electrochemical test methods to evaluate the relative effectiveness of 23 pipeline and 32 downhole corrosion inhibitors. The test methods were divided into:
Low-pressure linear polarization
High-pressure linear polarization and potentiodynamic
Wheel test, low pressure and high-pressure
Rotating cylinder electrode, laminar and turbulent flow
Disposal flow loop (vertical and horizontal flow)
High speed autoclave (500 and 2000 rpm)
2. Secondary Persistency wheel test
Persistency flow loop
|File Size||154 KB||12|