Don’t Let What’s Good Inside Corrode from the Inside Out
You heard that living near the beach can cause more corrosion due to salinity and humidity. So you can imagine how problematic the oil and gas equipment can be. Yes, oil and gas are produced together with salty water. But it isn’t only that! We have to deal with CO₂ and/or H₂S too. You can be a corrosion inhibitor at home, remove damaged areas and pass a spray on what you want to protect. In the industry environment (pipelines, well tubing, separators etc) isn’t so simple and if you don’t prevent corrosion, it can cost time, money and even lives (fishes for example). Are you interested to know more about? Keep reading.
Corrosion in Oil and Gas Environments
Corrosion is an electrochemical process in which metal reacts with its environment. Anodic and cathodic sites form on the steel surface, and when water and gases are present, current flows, creating a corrosion cell.
Common corrosion types found in operations:
- Uniform corrosion: steady, evenly distributed metal loss.
- Pitting corrosion: small localized holes; these cause failures fast.
- Galvanic corrosion: two metals, different potentials, same fluid; one corrodes faster.
- Under-deposit corrosion: solids or scale deposits trap corrosive species under buildup.
- MIC (microbiologically influenced corrosion): sulfate reducers and acid-producing bacteria attacking stagnant or low-flow zones.
As every chemical reaction, several factors influence corrosion. Temperature, salinity, water cut, flow regime, gas composition, pressure and biological activity are fundamental parameters to assess the risks and turning each well in a specific case that need to be carefully evaluated using software and expertise.
Downhole Corrosion Considerations
Downhole tubulars face particularly aggressive conditions. The presence of CO₂ and H₂S, high temperatures, and high-pressure brine systems accelerate corrosion inside casing and production tubing. Corrosion can attack both internal and external surfaces depending on the well design, completion fluid, and gas composition.
Selecting the right downhole corrosion control method depends on several factors:
- Partial pressures of CO₂ and H₂S
- Temperature and pressure profile of the reservoir
- Formation water production and salinity
- Flow regime and water-to-gas ratios
- Completion design (onshore vs. offshore)
The three main downhole corrosion control methods include:
- Corrosion-resistant alloys (CRA): high CAPEX, minimal long-term corrosion risk.
- Internal coatings or linings: moderate CAPEX, periodic maintenance.
- Downhole corrosion inhibitors: chemical treatment applied through continuous or batch injection; cost-effective and adaptable for variable well conditions.
The right prediction of the chemistry of fluids production are needed to determine the strategy associated to CAPEX. Produce more acidic gases than predicted can lead to catastrophic corrosion rates. Industry analysis estimates corrosion costs the upstream sector around $1.3 billion annually, with roughly one-third tied to downhole corrosion. Even using the best materials, it is still recommended the use of corrosion inhibitors. Now we can start talking about Chemicals.
How Corrosion Inhibitors Work
Corrosion inhibitors control corrosion by changing surface reactions. They adsorb onto metal, forming a barrier film that separates steel from corrosive fluids. Sometimes we inject chemistries that we want to stay in the fluid for the whole production time, other times we want they to stay there (reservoir or pipeline for example) and keep doing their jobs. Although Oxygen scavenging and H2S scavengers are in a different category, they also prevent high corrosion rates, but they have different mechanisms. Understand their chemistries is important to avoid incompatibility with corrosion inhibitor and maximize final efficiency.
Main functions:
- Film formation: inhibitor molecules have a polar head that bonds to steel and a hydrophobic tail that repels water. The film keeps corrosive ions away.
- Anodic/cathodic suppression: changes reaction kinetics, reducing electron flow and slowing metal loss.
Typical types of corrosion inhibitors:
- Film-forming amines and imidazolines
- Quaternary ammonium salts (quats)
- Phosphate esters for high-temperature or CO₂ service
Application methods:
- Continuous injection: capillary line feed, downhole or topside; maintains protective film.
- Batch treatment: slug dosing during pig runs or shutdowns; used in intermittent flow systems.
- Squeeze treatments: pump inhibitor into formation for gradual release into production fluids.
The efficiency of the film durability varies with shear, flow velocity, brine composition, application method and fluids composition. These industrial corrosion inhibitors play a primary role in maintaining asset integrity across upstream and midstream systems. Experience to advice operation conditions, application method and determine the best chemistries is needed to avoid strip the film or cause undesired outcomes such as oil emulsification or inefficacy.
Inhibitors for Specific Well Operations
Certain operations planned to optimize production use fluids that are highly corrosive. In those situation corrosion inhibitors are totally recommend in a different dose of normal production, for example. Below you can see examples when corrosion inhibitor can/should be used.
- Completion fluids: protect tubing and casing during displacement and packer setting.
- Acidizing and stimulation: safeguard steel from HCl or HF acid attack during well cleaning.
- Production fluids: maintain long-term protection against CO₂ and H₂S in produced water and condensate streams.
Imperative Chemical Partners have teams that work together bringing the expertise needed to determine the best method application, corrosion inhibitor chemistries and dose rate for your application and methodologies to confirm efficiency under high shear, high temperature, and multiphase flow.
Corrosion vs. Scale Inhibitors Differences
Corrosion inhibitors protect metal. Scale inhibitors stop mineral buildup such as CaCO₃ or BaSO₄ that restrict flow. They address separate issues that often occur together. In production systems, both are vital parts of corrosion & scale inhibitors programs.
| Inhibitor Type | Function | Targets |
| Corrosion Inhibitor | Prevents metal oxidation/reduction | CO₂ corrosion, H₂S attack, MIC |
| Scale Inhibitor | Stops mineral crystal growth and deposition | CaCO₃, BaSO₄, SrSO₄ |
In most systems, both are required. One protects steel, the other maintains flow. Imperative formulates dual-function blends that handle both challenges without disrupting separation. Keep following our blog to understand more about scaling inhibitors in the future.
Field Validation
From the lab to the field, we continue to check performance. There are different ways to do this:
- Coupons: measure weight loss over time; reliable, simple.
- ER probes: provide instantaneous corrosion rate readings.
- Fluid sampling: verifies inhibitor residuals and corrosivity levels.
Effective programs trend these readings and compare them with chemistry data, flow shifts, and maintenance schedules. Imperative uses digital dashboards for monitoring and performance tracking.
Matching Chemistry to Conditions
No universal solution exists. Proper inhibitor choice depends on metallurgy, temperature, pressure, water chemistry, and flow regime. Laboratory testing (wheel tests, autoclave runs, compatibility checks) determine film strength and persistence before deployment.
Imperative’s labs simulate field environments to measure shear stability and emulsion behavior. Field engineers then fine-tune dosage and injection frequency once operations begin.
Because you know, more inhibitor isn’t always better. Overdosing can destabilize emulsions or worsen corrosion if chemistry doesn’t match brine or crude. But if you don’t know, it isn’t a problem. Contact us.
Partner with Imperative Chemical Partners
Corrosion management is continuous evaluation, monitoring, and precise chemistry application, not a one-time fix. Effective corrosion & scale inhibitors programs keep production flowing and assets protected.
Imperative Chemical Partners supports over 85,000 wells and 45,000+ miles of midstream infrastructure for 800+ operators. If corrosion impacts production or uptime, talk to a chemical solutions team that’s solved it in the field.