Assessment of Corrosion Rates Under High Shear Conditions - Developments in Laboratory Testing

Abstract

Abstract The use of inflow-control valves (ICVs) and inflow-control devices (ICDs) to improve production rates in horizontal wells has become increasingly common in recent years. These devices have small apertures resulting in high, local high flow rates which results in regimes of very high shear and turbulence, potentially resulting in materials failure due to accelerated corrosion rates, erosion and potentially erosion-corrosion. To meet the challenge of testing accelerated corrosion rates, various laboratory methods have been developed to study the effects of increasing shear on corrosion. Common test methods such as rotating-cylinder electrode (RCE) tests can provide useful data at moderate shear stresses (up to 100 Pa) and ambient pressures, while rotating-cage autoclave tests (RCA) and rotating-cylinder electrochemical autoclave (RCEA) tests allow moderate shear tests to be conducted at elevated temperatures and pressures. However, achieving the very high wall shear stresses seen with certain oilfield jewellery, such as ICVs and ICDs, is significantly more challenging. In contrast, jet impingement (JI) methods have enabled materials testing at up to 10,000 Pa, and by coupling these with the ability to conduct these tests under increasingly higher pressures and temperatures, very-high-shear systems can be tested under conditions closely matched to those in the field. The approaches developed in our laboratories, which use both weight loss and electrochemical corrosion measurements, have also proved to be robust even in extremely corrosive environments, such as in the presence of stimulation acids (both uninhibited and inhibited) and over extended exposure times (> 7 days). These jet-impingement test methods have enabled enhanced understanding of the susceptibility of various materials to corrosion and erosion under extremely high shear conditions, and how effectively (or not) film-forming corrosion inhibitors perform. The application of these advanced laboratory techniques is currently playing a vital role in evaluating suitable methods for preventing corrosion under very challenging conditions before deployment in the field.