Oilfield Corrosion Inhibitor

An Oilfield Corrosion Inhibitor works to prevent or slow down corrosion by forming a protective layer on metal surfaces that are exposed to corrosive agents. This protective layer can be composed of several components, depending on the type of inhibitor and the specific application.

Some common mechanisms by which Oilfield Corrosion Inhibitors work include:
Cathodic Protection: Inhibitors can act as cathodic protectors, preventing the formation of corrosion cells by reducing the anodic reaction rate. This mechanism involves the donation of electrons to the corroding metal surface, which reduces the driving force for corrosion.

Formation of a Passivation Layer: Certain inhibitors can form a protective layer on the metal surface, known as a passivation layer, which prevents corrosive agents from coming into direct contact with the metal. This layer can be composed of various materials, such as oxide films, hydroxides, or other compounds, depending on the inhibitor used.

Chelating Agents: Some inhibitors contain chelating agents that can bind tightly to metal ions, preventing them from participating in corrosion reactions. By complexing with the metal ions, these agents prevent them from being oxidized and thus slowing down the rate of corrosion.

Neutralization of Corrosive Agents: Oilfield Corrosion Inhibitors can also work by neutralizing corrosive agents, such as acids or dissolved oxygen, in the oil or water phase. This can be achieved through chemical reactions between the inhibitor and the corrosive agent, forming harmless products that no longer pose a threat to the metal surface.

It's worth noting that the effectiveness of Oilfield Corrosion Inhibitors can vary depending on factors such as the type and concentration of corrosive agents present, the pH of the environment, the temperature, and the specific properties of the metal surface. Therefore, selecting the appropriate inhibitor for a given application requires careful consideration of these factors.

According to a recent study by the Association for Materials Protection and Performance (AMPP, previously NACE), corrosion is responsible for over $2.5 Trillion (with a "T") of loss and damages each year to the global economy. For those keeping score, that's 3.4% of global GDP.
This is simply astounding. Clearly, inhibiting corrosion is of utmost financial importance to global industry.

First, it's helpful to address specifically what is corrosion in oil and gas. Put simply, corrosion is the process by which refined metals, like steel, undergo a chemical reaction that causes the chemical or electrochemical deterioration of the metal.
In oil and gas processes, corrosion of metal equipment typically occurs from one of the following processes
Sweet Corrosion - metal is exposed to carbon dioxide (CO2) or oxygen (O2) when water is present
Sour Corrosion - metal is exposed to hydrogen sulfide (H2S) when water is present
Microbial Induced Corrosion (MIC) - metal is exposed to corrosive waste products, such as CO2, H2S, and acids produced by bacteria
Galvanic Corrosion - metal corrodes when exposed to other metals in an electrolyte, often impure water
In many cases, corrosion inhibitors are used to prevent these types of corrosion in oil and gas processes.

A corrosion inhibitor is a chemical compound designed to prevent or postpone the process of corrosion through physical or chemical means.
Corrosion inhibitors are used as a steady-state additive to oil and gas processes, meaning they are continually injected to prevent corrosion.
Corrosion inhibitors are just one way that the oil and gas industry combats corrosion. Other methods include cathodic protection, protective coatings, and appropriate material selection.

In the oil and gas industry, there are 3 main types of chemistries used to inhibit corrosion:
Film-forming Corrosion Inhibitors
Film-forming corrosion inhibitors physically prevent corrosion by forming a film on the interior of a pipeline or vessel. This film repels water containing corrosive elements, preventing contact with the pipeline surface. There are many types of chemistries used in film-forming corrosion inhibitors, though azole and pyrimidine byproducts are often used. In certain cases, film-forming corrosion inhibitors can also be used to prevent the build-up of unwanted precipitates, such as scale, on pipeline internals. These are often called "mixed inhibitors" or "combination inhibitors."

Gas scavengers, such as oxygen scavengers, carbon dioxide scavengers, and hydrogen sulfide scavengers, inhibit corrosion by chemical converting corrosive gases into non-corrosive materials through chemical interactions. These chemistries often contain triazine or various amines.

Biocides inhibit microbial-induced corrosion (MIC) by killing and preventing the formation of bacterial colonies. Glutaraldehyde is a common biocide used in the oil and gas industry.

These three types of corrosion inhibitors are injected into oil, water, and natural gas processes to prevent equipment, pipeline, and vessel corrosion.

The challenge, of course, is figuring out how much corrosion inhibitor to inject. Because many of these chemistries can create headaches for downstream processes and refining, it's important to minimize chemical overuse. At the same time, under-injection puts assets at risk of failure.

As such, oil and gas operators and their service providers are looking for better ways to dial in injection rate calculations for corrosion inhibitors and automate treatment concentrations.

Because precise chemical injection of corrosion inhibitors is critical for cost reductions across all oil and gas processes, operators of all sizes should consider economic means of automating the injection of corrosion inhibitors.
Here are 3 useful tips for automating corrosion inhibitor injection in oil and gas processes.

● Use a flow meter
One of the simplest ways to minimize the waste of corrosion inhibitors while maintaining acceptable asset integrity is to use data from a real-time flow meter to inform injection rates.
In most cases, film-forming inhibitors are injected at precise concentrations into a process based on known water cuts and impurity levels in that process. Assuming these percentages remain stable, a flow meter can inform the necessary volume of corrosion inhibitors based on a prescribed concentration.
This is especially useful in processes where flow rates fluctuate considerably day-to-day, such as in saltwater disposals or produced water transfer systems.

● Measure downstream to inform future applications
One of the most common ways to ensure proper treatment levels of film-forming inhibitors is to measure chemical residuals downstream. Measuring residuals involves sampling downstream fluids to detect concentrations of corrosion inhibitors in the process.

If corrosion inhibitors are being applied in appropriate concentrations, there should be some, though minimal, residual chemistry downstream. If no residuals are present, we might assume we aren't getting complete protection. If we measure too many residuals, then we can assume we are over-treating.

Similar to residual measurement, companies should begin measuring actual corrosion in equipment downstream of corrosion inhibitor injection using corrosion probes. This process of "closing the loop" can, over time, show how effective corrosion inhibitors are at actually preventing corrosion.
The process of measuring corrosion can be challenging, of course. It can be difficult to know where to place the probes and when to take readings. In single applications, this may be of little use.

● Measure actual chemical usage
For any oil and gas operator or service provider keen on reducing the cost of corrosion and corrosion inhibitors, the above two methods can go a long way.
However, these two methods must be informed by accurate chemical usage data.
Too often, it is assumed that actual chemical dosage occurs at the prescribed rate. The after-the-fact analysis assumes that, if the pump was set to 15 GPD, then it injected 15 GPD over that time period.
In reality, this assumption is categorically false, and if relied upon will continue to confound those trying to optimize their corrosion inhibitor automation programs.
WellAware has surveyed thousands of chemical injection systems across the world. We've monitored and automated systems that have injected over 860,000 gallons of corrosion inhibitor last year.

Discharge of Contaminated Water: Corrosion inhibitors can leach into produced water or wastewater during oil and gas production, potentially contaminating surface waters or groundwater if not properly treated before discharge.
Impact on Ecosystems: The chemicals found in corrosion inhibitors could have detrimental effects on aquatic life, such as altering the pH balance or interfering with the natural biological functions of organisms.

Proper Handling and Disposal: Corrosion inhibitors should be handled according to strict safety protocols and disposed of through proper waste management facilities that can treat the water to remove contaminants before discharge.

Water Management: Operators should implement effective water management strategies to reduce the volume of produced water and recycle or reuse as much as possible, minimizing the need for fresh water and the discharge of treated water.

Chemical Reduction Technologies: Employing technologies that reduce the amount of chemical additives required, such as advanced materials and coatings, can help decrease the environmental footprint of corrosion inhibitors.

Environmentally Acceptable Inhibitors: Investigate and use corrosion inhibitors designed with environmentally friendly chemistries that pose less risk to ecosystems if accidentally released.

Regular Monitoring and Testing: Regularly monitor and test the wastewater for contamination, ensuring that it meets regulatory standards before being discharged.

Training and Awareness: Provide training to personnel involved in handling corrosion inhibitors to increase awareness of the potential risks and the importance of following proper handling procedures.

Collaboration with Regulatory Bodies: Work closely with environmental agencies and adhere to local regulations and international standards to ensure that the use of corrosion inhibitors is within acceptable environmental limits.

By implementing these measures, the oil and gas industry can mitigate the environmental impact of oilfield corrosion inhibitors while still protecting the integrity of oilfield assets.