Introduction

Loss of hydrocarbon containment due to corrosion can result in severe consequences not only with respect to safety, but also to the environment and the commercial profitability of the organization.

A widely used strategy for corrosion control is the application of corrosion inhibitors that have a typical operational life of 15 years in a field. In 2015, the global corrosion inhibitors market size was estimated to be worth USD 5.99 billion ^[1].

By definition, a corrosion inhibitor is a chemical that can be injected to effectively minimize corrosion. Inhibitors are either water soluble or oil soluble, but they also can be dispersible in either media. Different classes of inhibitors aid in slowing corrosion mechanisms by different processes.

Some examples of corrosion inhibitors are:

• Passivating (anodic) Inhibitors
• Precipitation Inhibitors
• Organic Inhibitors

Continuous corrosion inhibitor injection for hydrocarbon systems typically uses complex formulations with multiple active ingredients.

Chemical Selection Pitfalls

There are several challenges associated with the selection of inhibitors and the in-service performance of inhibitors.

These challenges include:

• Inadequate definition of field conditions, leading to selection of inhibitors to be tested that are not fit for purpose
• The use of sub-optimum conditions in testing where laboratory test conditions do not replicate the in-service conditions.
• Basic testing where testing is limited to a small number of tests that do not assess critical performance characteristics
• Biased reporting from non-independent third party laboratories that reports results that infer superior performance of their own preferred inhibitor/s
• Over-inhibition occurs where the optimum dosage of corrosion inhibitor has not been identified and more inhibitor than necessary is injected, leading to potential flow assurance problems such as foaming and emulsions and excessive and unnecessary costs.

Optimum Approach to Inhibitor Selection

AIE performs complete independent assessment of corrosion inhibitors from product selection, through test programme design, management, and technical evaluation, to field testing.

The optimum approach to inhibitor selection begins with the design of a suitable test program and the careful selection of a range of inhibitors from qualified chemical vendors.  The chemical vendors should be apprised of the field conditions so that as a first pass they can recommend products that have been formulated for similar field conditions, e.g. sour or sweet conditions, high chlorides, high total dissolved solids (TDS) etc.

A fully representative sample of the crude oil from the field should be collected so that testing can be performed in actual field fluid. For gas condensate, an artificially formulated sample would typically be used.  Furthermore, the worst-case water conditions should be established so that an effective corrosion inhibitor can be selected after rigorous testing.

Specialist independent third party laboratories should perform testing of the inhibitors as they have the necessary testing equipment and professional resources needed to perform the testing and provide conclusive results. This will, in turn, aid in the elimination of reporting bias.

The whole selection and testing process should be designed and managed by chemical and corrosion management specialists. Specialized oversight is critical during the corrosion inhibitor selection process, intended to evaluate and eliminate problems that can arise at an early stage and limit the potential of the selection of sub-optimal or inadequate corrosion inhibitor.

Once a chemical is selected based on an engineered set of performance criteria which not only validates corrosion control other aspects such as flow assurance, compatibility and cost, a robust transition strategy is then employed to ensure the chemical is deployed in a safe and optimum manner.

Our chemical selection and management service continues to save clients millions of dollars in preventing over injection, improving corrosion control and maximizing flow assurance.

If you would like to understand how AIE’s team can support your requirements in this area, please visit our contact us page and we will promptly respond to your inquiry.

Providing a holistic approach for corrosion, chemical and flow assurance management, our market leading software, Veracity CCM enables operators to manage their key threats more effectively thereby maintaining plant up-time whilst reducing unplanned maintenance and costly repairs.

To learn more about Veracity CCM, click here.

To request a free demo, contact us.

Reference

[1] Corrosion Inhibitors Market Size | Industry Report, 2024″, Grandviewresearch.com, 2016. [Online]. Available: http://www.grandviewresearch.com/industry-analysis/corrosion-inhibitors-market. [Accessed: 09- Nov- 2016].