L51784 CO2-HS Corrosion Under Wet Low-Flow Gas in Presence of Bicarbonate Chloride and Oxygen

Abstract

The ability to transport wet, untreated natural gases through pipelines offshore or at other inaccessible locations is an important factor in the development of new gas fields. When a wet gas contains CO2 and H2 S, the internal corrosion rate of steel pipelines may be expected to increase. Considerable work has been done to define effects of CO2 and H2 S on corrosion rates of pipeline, casing, and tubing steels, particularly at higher pressures and temperatures typical of downhole environments and in gases in which CO2 is the only acid gas present. In particular, studies by de Waard and Milliams resulted in development of an equation for predicting corrosion rates of steels exposed to water saturated with natural gases containing CO2 . However, the de Waard-Milliams equation cannot be used for gases containing H2 S, since it is applicable when CO2 is the only acid gas present. This report was specifically initiated to provide estimates of internal corrosion rates in inaccessible (offshore) pipeline locations from analyses of gas and water samples taken in accessible (onshore) locations. It addresses the ability to transport wet, untreated natural gases through pipelines offshore or at other inaccessible locations, and the internal corrosion rates of steel pipelines.