Testing and Treating H2S and Mercaptans in Crude Oil

Testing and Treating H2S and Mercaptans in Crude Oil 

H2S monitor

We recently attended a conference in Salt Lake City, where we discussed various testing methods for H2S and mercaptans. Given the significant interest in this topic, we want to provide an overview for those who could not attend. Crude oil, a crucial resource in the energy industry, often contains unwanted contaminants such as Hydrogen Sulfide (H2S) and Mercaptans. These compounds not only impact the oil’s quality but also pose substantial health and safety risks. In this blog, we will delve into the testing and treatment methods typically used for these compounds. 

A Brief Overview of H2S & Mercaptans 

Hydrogen Sulfide (H2S): 

H2S is a toxic and pungent gas found in both the formation and post-production phases of crude oil. It is present in crude oil, natural gas, and water, earning it the nickname “sour gas.” H2S is soluble in water and behaves like a weak acid, making it corrosive. 

Mercaptans (RSH): 

Mercaptans are organic molecules with a structure resembling alcohol but with a sulfur atom chained to hydrocarbons, known as thiols. There are many mercaptan species, and they are notorious for their unpleasant odor. The human nose can detect mercaptans at concentrations as low as 10 parts per billion (ppb). 

Testing Procedures 

Testing for H2S and Mercaptans is a crucial step in ensuring the quality and safety of crude oil. However, not all testing methods are created equal, and the choice of method often depends on the commercial contract. Some common testing methods include: 

Vapor Testing 

  • ASTM 5705 modified: A test that yields results in H2S concentration (ppm/v). It has been modified to test crude oil since it was originally designed for fuel oil testing. 

Liquid Testing: 

  • ASTM D7621: A standard method for determining H2S in fuel oils by rapid liquid phase extraction. 
  • UOP 163: A titration that measures H2S (ppm/w) and mercaptan (ppm/w) concentrations. 
  • ASTM D5623: A GC method that provides H2S (ppm/w) and mercaptan speciation (ppm/w) data. 
  • ASTM D130-9/D1838-16: A subjective copper strip test for specific sulfur contaminants. 

Results obtained through these tests are vital for H2S scavenging, ensuring safety, and adhering to contract specifications. Historically, there has been a lack of correlation between different test methods, emphasizing the importance of using a consistent method throughout the process. In the United States, UOP 163 and ASTM 5705 are commonly used for crude oil quality contracts. 

Challenges with Testing Methods 

  • ASTM 5705 modifications may be necessary to adapt to crude oil testing conditions, and there is no standardized temperature for testing in practice. 
  • Reading stain tubes can be challenging. Moisture in the air and other contaminants in the raw crude oil may negate the accuracy of the tube. 
  • UOP 163 may suffer from interference by chemical contaminants and variations in technicians’ interpretations of titration curves. 

Scavengers for H2S and Mercaptans 

To address the presence of H2S and Mercaptans in crude oil, various scavenging methods are employed. These include: 

  1. Typical Amines:
  • Monoethanolamine (MEA) 
  • Diethanolamine (DEA) 
  • N-methyldiethanolamine (MDEA) 
  • Diglycolamine (DGA) 
  1. Non-Regenerative H2S Scavengers:
  • Solid, basic metallic compounds 
  • Oxidizing chemicals 
  • Aldehydes, including Formaldehydes 
  • Reaction products (may include triazines) 
  • Metal carboxylates/chelates 
  • Other amine-based solutions 

Each of these chemical solutions has its advantages and disadvantages, making it necessary to evaluate them on a case-by-case basis. 

Alternatives to Treat H2S 

In addition to scavenging methods, nitrogen stripping is an alternative approach to treat H2S. This method involves bubbling nitrogen through a column, which attracts H2S, allowing lighter-end volumes to escape and be transported to a flare. However, this process comes with its own set of considerations, including the need for a compressor, a nitrogen membrane generation unit, stripping tower kit, and a tie-in to the flare line. Moreover, the loss of hydrocarbons at the flare may raise environmental, social, and governance (ESG) concerns. 

Why It Matters 

Understanding and effectively addressing H2S and Mercaptans in crude oil is essential for various reasons: 

  • Prolonging Asset Life: Proper treatment ensures that your assets last longer, maximizing their value. 
  • Expanding Markets: High-quality crude with low H2S and Mercaptan content opens doors to more markets. 
  • Building Optionality: The ability to adapt to different market conditions leads to better netback prices. 
  • Ensuring Personnel Safety: Protecting the health and safety of workers is of utmost importance. 
  • Asset Integrity: Treating H2S and Mercaptans preserves the integrity of equipment and facilities. 

 Managing H2S and Mercaptans in crude oil is a critical aspect of the industry. By understanding the characteristics of these compounds, employing appropriate testing methods, choosing effective scavengers, and considering alternative treatments, companies can ensure safer operations and better financial outcomes. Ultimately, the equation for success in the industry is the combination of the highest quality and merchantability, resulting in the highest netback prices. 

Final Thoughts  

Understanding and complying to the commercial contract is paramount. These commercial contracts will stipulate which method is required to meet specifications, so when in doubt, have the operations team speak to the crude quality or commercial teams to understand the exact parameters to ensure the quality of the crude is being met for final delivery. 

The Science of H2S Removal: Our Oilfield Chemical Solutions

The Science of H2S Removal: Our Oilfield Chemical Solutions










As one of the leading H2S scavenger manufacturers and oilfield chemical suppliers in the industry, Q2 Technologies is committed to delivering high-quality H2S removal solutions to its clients. We understand the importance of removing H2S from natural gas and crude oil, as it is a toxic and corrosive gas that can cause serious damage to pipelines, equipment, and the environment. In this blog post, we will discuss the science of H2S removal and how our oilfield chemical solutions can help. 

H2S Scavengers: How they work 

H2S scavenger technologies are used to remove hydrogen sulfide (H2S) from natural gas and crude oil streams. There are various chemistries used for H2S scavenging, including nitrite-based, triazine-based, iron sponge, and caustic-based methods. 

Nitrite-based scavengers work by oxidizing H2S to elemental sulfur in the presence of oxygen. These scavengers can also provide corrosion inhibition, making them a popular choice in certain applications. 

Triazine-based scavengers react with H2S to form stable, non-toxic compounds that can be easily separated from the treated gas or liquid. They are often used in natural gas processing and refining. 

Iron sponge is another common H2S scavenger. It works by using iron oxide to react with and remove H2S from gas streams. 

Caustic-based scavengers (such as sodium hydroxide) react with H2S to form sodium sulfide, which can then be further treated or disposed of. They are commonly used in refineries and other industrial processes. 

Each H2S scavenger has its advantages and disadvantages, and the choice of scavenger depends on several factors such as the composition of the production stream, operating conditions, and environmental regulations. However, with careful selection and application, H2S scavengers can effectively reduce the risks associated with H2S gas in the oil and gas industry. 

H2S Removal Solutions from Q2 Technologies 

At Q2 Technologies, we offer a range of H2S removal solutions to meet the needs of our clients from liquid non-triazine products, iron-based scavengers, to more traditional triazine based scavengers, all designed at removing H2S from crude oil and natural gas. Specifically for crude oil and liquid hydrocarbons, Pro3® is a non-triazine scavenger that offers several advantages over other H2S scavengers, including: 

  1. High H2S removal efficiency: Pro3® is highly effective at removing H2S from crude oil streams, even at low concentrations. This is due to its unique chemical composition, which enables it to react with H2S and convert it into sulfate byproducts which drop out into the BS&W. 
  2. Long-lasting protection: Pro3® provides long-lasting protection against H2S, which reduces the need for frequent scavenger injections. This can help to reduce costs and increase operational efficiency. 
  3. Environmentally friendly: Pro3® is a non-triazine-based H2S scavenger, which means it does not contain triazine or amine compounds that can be harmful to the environment. 
  4. Compatible with other chemicals: Pro3® is compatible with other chemicals commonly used in oil and gas operations, including corrosion inhibitors and demulsifiers. This makes it easier to integrate into existing operations. 

Overall, Pro3® offers a high-quality, effective, and environmentally friendly solution for H2S removal in the oil and gas industry. Its unique chemical properties and benefits make it a preferred choice for many Producers and Midstream companies looking to improve their H2S removal processes. 

In addition to Pro3®suite of products, Q2 Technologies offers several other products from this chemical line including  ProM®  and Pro3®HT , all H2S scavengers for the removal of hydrogen sulfide from  crude oil and liquid hydrocarbon streams. ProM® is an oil dispersible  option that is ideal for combating against certain species of mercaptans (a similar sulfur-based compound). Pro3®HT is a specialized product designed for high-temperature applications, with stability and effectiveness up to 150°C (302°F).  

For sour natural gas applications, we offer a range from traditional triazine-based products to non-triazine products in both liquid and dry media applications.  

  1. Triazine based scavengers, if properly managed, can be a standard approach to treating H2S. We also provide a vast range of field strength concentrations as well as several additives that can be used for greater effectiveness or for compatibility concerns. 
  2. We also have a non-triazine/non-amine alternative to MEA triazine: Pro3®GT & Pro3®GT+ are specially formulated to have the same outcome as triazine. However, GT & GT+’s reactions are not subject to the same side effects one experiences when overtreatment occurs with triazine, such as scale or buildup of particulates. Further, Pro3®GT & Pro3®GT+ has more kinetic prowess than triazine, typically using 20% less overall product when compared to triazine. 
  3. Lastly, Pro3®Nano is our innovative dry media that can effectively target H2S in sour natural gas streams that tend to have significant production swings or experience massive ranges in H2S. This product can handle any environment and will provide a sweetened gas stream consistently. With a regenerative aspect, this system is a great change to traditional liquid systems, where the product can be re-energized in system. 


The importance of removing H2S from natural gas and crude oil cannot be overemphasized, as it is a toxic and corrosive gas that can cause serious damage to pipelines, equipment, and the environment. Q2 TechnologiesPro3® H2S scavenger, along with its other products, offers a unique and effective solution for H2S removal, with advantages such as high H2S removal efficiency, reduced iron sulfide formation, long-lasting protection, and environmental sustainability. With a range of options available, Q2 Technologies offers tailored H2S removal solutions that meet the specific needs of its clients, making it an ideal partner for any oil and gas operation. 

If you are interested in learning more about our H2S removal solutions, please contact us. Our team of experts is always ready to answer any of your questions. 

Complete H2S guide for Health and Safety

Hydrogen Sulfide (H2S) is a highly corrosive chemical found in Crude Oil, Natural Gas, Production Water, and Formation Water. The presence of H2S in Crude Oil and other volumes plays a significant health risk for those close to or exposed to this noxious substance. Because of its toxicity, if inhaled it can lead to numerous health problems and, in some cases, even death. Workers in the oil and gas Exploration, Production, Midstream,  and Refining Industries may be exposed to this hazardous substance so they must follow a set of safety measures that are outlined below. Please consider the following as a starting point, always consult your company’s EH&S or manager for safety specific requirements.


Why is H2S so dangerous?


  • The health consequences of hydrogen sulfide depend on how much and how long the worker breathes it in. Exposures to concentrations of 100 ppm or more are harmful to human health. However, even at low doses, significant impacts are observed. The effects range from moderate, such as headaches or eye discomfort, to extremely dangerous, such as permanent loss of smell and taste to unconsciousness and death. 


  • In oil and gas applications, sour gas and sour crude (which contains H2S) can react with air and moisture to produce sulfuric acid, which can corrode metals. The durability and impact strength of facility equipment, particularly the inside surfaces of different components, are diminished, eventually resulting in premature failure.


Safety Equipment


H2S Monitor

  • Always make sure to carry an electronic meter that detects hydrogen sulfide gas. And clip the monitor near your face, on the lapel of your shirt for example.  Always “bump test” by clicking the test button on the monitor prior to entering any job site to ensure the alarm on the monitor is loud –  there may be large decibel producing equipment creating loud noises, your monitor should be louder so you can hear it.
  • Do not rely on your sense of smell to detect the presence of hydrogen sulfide or to alert you of dangerous amounts. At low quantities in air, hydrogen sulfide has a “rotten egg” smell. However, after a while, you lose your capacity to detect the gas even if it is still present (olfactory fatigue). In large quantities, this loss of smell can occur extremely quickly, and the ability to detect the gas can be gone instantly (olfactory paralysis).


Protective personal equipment


  • Wear respiratory and other personal protective equipment.
  • Make sure you have been properly mask fitted to make sure you will be protected from hazardous vapors.
  • If measures fail to lower H2S levels below the allowed exposure limit, respiratory protection must be used as well as additional personal protective equipment (PPE) such as eye protection and perhaps fire-resistant clothing. 


Safety Measures


Imagine your hydrogen sulfide sensor has gone off, indicating the presence of H2S in your work environment. Now, what do you do?


1. Put On Your Gear:

Put on your gas mask if you have one handy and aren’t already wearing one. Pull your straps down firmly and breathe. While you evacuate the area, your mask will keep you safe. 

The requirements for carrying a mask differ based on the setting, so if you don’t have one, don’t worry, just go on to the next stage.

2. Get Upwind: 

  • If you’re working in an area with the possibility of H2S release, there should be flags or windsocks on the work site to show you which direction the wind is blowing. Head in the opposite direction immediately. If you can’t see the windsock, toss some dirt or leaves into the air, or look at the trees. 
  • The wind can blow and concentrate the H2S into valleys or stands of trees, so the direction you go is essential. If you see a designated gathering area, or “muster site” downwind, go there. 
  • This is the easiest and most effective way to avoid H2S inhalation or poisoning.
  • Lastly, if your work plan makes it difficult to evacuate an area, consider revising your work plan with your team before starting work in the first place.

H2S Removal

H2S Scavengers should be employed by crude oil companies to benefit from less fouling, corrosion, and property damage, significant reduction of health risks, and a potential increase in the value of production barrels.  


In conclusion, anyone who has the possibility of being exposed to H2S must be ready with the recommended safety equipment and the know-how for whenever the H2S monitor goes off.

Always carry:

  • H2S monitor
  • Properly fitting PPE

If the monitor goes off, remember to:

  • Put on your gear
  • Get upwind


Q2 Technologies manufactures specialty H2S Scavenger Chemistry products that remove H2S from millions of barrels of oil every month. For more information, contact us









Cracking the Code on Treating H2S: Q2 Technologies’ Non-Triazine Scavengers Reducing Chemical Use Up to 75%

When it comes to treating Hydrogen Sulfide (H2S) in Crude Oil and liquid hydrocarbons, there are several types of triazine-based compounds that have historically been used. Unfortunately, if not closely monitored, the by-products of many of these chemistries can actually be more operationally detrimental and thus vastly more expensive, because overuse may cause corrosion and fouling in downstream systems. Fortunately, new technology has emerged! Q2 Technologies boasts a revolutionary new product that is in a class all by itself: Pro3® is an innovative non-triazine and non-amine H2S scavenger for Crude Oil and liquid hydrocarbon applications that is able to reduce chemical use up to 50-75% as compared to Glyoxal and MEA Triazine.

Less chemical

Pro3®’s active ingredient is chemically more effective and efficient at rendering H2S into non-reversible components than triazine could be, chemically speaking Pro3® is superior to triazine.

In a recent study, Pro3®, a non-triazine scavenger, was recommended to substitute a 40% MEA-triazine scavenger, resulting in an 80% cut on chemical consumption compared to triazine. This resulted in a reduction in deliveries and lowered the overall chemical spend. Read more about this case study here.

No Fouling and Corrosion

Q2 Technologies’ non-triazine product does not contain any amines or nitrogen compounds, making it 100% safe for refineries and pipelines. Amine salts from triazines can end up doing more damage to the top stacks of a refinery when heated to +500 °F as compared to the pinhole corrosion that H2S would cause if routed through the refinery untreated. 

Refinery Tower Diagram
Refinery Tower Diagram

The distillation column is the backbone of any refinery and keeping the internals free of corrosion is critical. Refineries that manage asset integrity are constantly evaluating the inlet volume for amines and monitoring the physical nature of the columns.

Effect on supply chain

In the Spring of 2021 there was a significant winter storm event in Texas which had far reaching implications for the triazine market for much of the United States, and consequently Canada and parts of South America. The week-long deep freeze shuttered many chemical plants, and by the company’s estimates, nearly 90% of plants along the Gulf Coast that create the raw materials for triazine were shut down for months. This caused the near-commodity price of triazine to skyrocket: a classic under supply situation resulted in higher demand and the Oil & Gas producers and consumers were hindered by this for over a year. Q2 Technologies monitored this phenomenon closely.  Since our Pro3® is a non-triazine based product, there were no supply chain issues and prices were not affected. Unfortunately, for those that depend heavily on triazine as a main scavenger, the threat of a shutdown could easily happen again, as some plants simply did not come back online in the summer of 2021, and those that were were repaired carry the additional operational burden to produce more and more triazine.

If scavenger costs and operational concerns are a priority, learn more about Pro3® and see how Q2 Technologies can lower your net chemical usage, protect infrastructure, and increase overall hydrocarbon production by rending H2S out. If you think your project can benefit from using Pro3® contact us today

Removing Mercaptans While Keeping Costs in Line

There are several choices when it comes to treating mercaptans. Since mercaptans are highly complex branched sulfur-based hydrocarbon chains, treating them may require expensive solvents and scavengers, making it quite costly; not to mention that if treated with amine-based scavengers, dealing with fouling and corrosion is another expense to add. These factors were the impetus for developing ProM® for our clients, a mercaptan-treating product for meeting specs economically without having to deal with the effects of amine-based scavengers. By treating with ProM®, one can optimize the treatment process which can minimize the need for expensive blend stock or can even eliminate it. In this blog, we want to show you how our ProM® works and why it’s been a game changer for our clients. 


What is ProM®?

ProM® is a mercaptan Scavenger. It has been specifically engineered to use non-triazine, non-amine based chemicals, which makes it safe to be used at refineries. This mercaptan removal technology is effective against Methyl, Ethyl, Isopropyl, Tert-Butyl, n-Propyl, sec-Butyl, Isobutyl, and n-Butyl mercaptans, just to name a few.


How does it work?

As we mentioned, unlike H2S, mercaptans are highly complex branched sulfur-based hydrocarbon chains, so they require lab analysis to determine treatment approach. Let’s say you are considering ProM® as an option, in order to know how much product your specific project needs, we would follow these steps:

  1. First, a lab analysis using method UOP163 and ASTM – D5623 is required to determine the mercaptan levels in ppm/w or the full speciation, respectively.
  2. Once analyzed, the appropriate dosing of ProM® chemical is determined.
  3. Then, we inject the product. Injecting on the suction side of the discharge pump allows for excellent contact and churn, ensuring the reaction is effective. The confluence of the chemical in Crude Oil ensures efficient mixture and treatment. 
  4. Finally, a test confirms that quality spec has been reached and the vessel may proceed.


Mercaptan removal process.
Process for determining ProM® dose.


Mercaptan removal allows for better net back pricing on the barrel while meeting safety standards and protecting assets.



A real life example

A 50,000 bpd condensate splitter was facing fouling issues from MEA-Triazine. Also, they were using very high volumes of MEA-Triazine and still failed to reach crude oil mercaptan specification. As if this wasn’t enough, the terminal was required to blend down various types of crude oil from different storage tanks to achieve a mercaptan specification ranging from 2-5 ppm.


We’d seen that before, so we recommended ProM® to meet mercaptan specifications at the terminal to reduce the amount of blending required and reduce fouling and corrosion problems at neighboring condensate splitters. The results? ProM® chemistry allowed the customer to meet mercaptan specifications that MEA-Triazine was unable to reach. Here’s a link to this case study for your reference.


Lately we’ve been seeing increasing interest on this type of treatment because as we all know, everything keeps evolving, there’s no need to sacrifice one thing or the other anymore, by using ProM® you can:

  • Meet specs
  • Protect your assets
  • Reduce or even eliminate the need for expensive blend stock
  • Get better net back pricing on your barrel
  • keep your costs in line


If you are looking for this type of solution, we’ll be happy to help, give us a call or send us an email.

Treating Trucked Sour Crude

Unique Treatment Solutions

Unique Treatment Solutions

Barrels that have moderate to high levels of H2S are typically challenged economically from the start. First, from a safety standpoint – more oversight, training, CAPEX & OPEX, and effort goes into protecting the people and assets involved. Next, the untreated barrel will likely get rejected commercially and will not move via pipeline, which leaves trucking that sour barrel to market as the only alternative. Unfortunately, as a double whammy, that trucked sour barrel typically goes to a market that stacks yet another financial hardship on its value: a dreaded sour oil deduct on the netback price. The value erosion on that barrel can be a significant drain on the Producer, and in some plays the whittling away on the sour barrel can be borderline uneconomic. Ugh!



With higher overall WTI per barrel in Q4 2021, more production is likely on the way to realize the price bump. In fact, production in the Permian is heading back to pre-pandemic levels increasing output to an average of 4.826mmbls/d in October, according to a recent ClusterX article citing a U.S. government report. Which is just shy of the record set in March 2020 at 4.913mmbbls/d right before COVID-19 fundamentally disrupted global demand and sent supply reeling. Although the industry has done a good job in the previous years building out the gathering and long-haul pipeline systems, trucking fills in the gaps. Although difficult to pin down an exact number, trucking in the Permian has always filled the takeaway gap and according to several historical reports, several thousand truck haulers operator daily – which means potentially a quarter million+ barrels are being hauled in the Permian at any given time. And in this case for sour barrels, Producers and Midstreamers rely heavily on this critical delivery component. It can be challenging to commit capital to build pipelines to inherently less valued barrels due to the presence of their sulfur content, and so, many sour barrels are stranded in the field to be delivered only by truck.

Fortunately, there are treatment solutions available, and economic ones a that! Q2 Technologies recently implemented a system for a leading Midstream company to accept H2S barrels to treat automatically at an existing multi truck lane LACT station. This novel approach makes economic sense to all parties involved; here’s how it works:

Once the oil hauler, who is transporting a sour barrel, begins pumping volume at the facility, the lease automatic custody transfer (LACT) sends a signal to the Q2 pumps to being dosing. The crude oil is then treated as it is transferred in the tanks. Once treated, the barrel meets H2S specifications and can be sold into a sweet market. This setup is capable of treating all lanes simultaneously several thousand barrels per day at H2S levels in tens of thousands of ppm. 

Net benefit to all:

Producers are able to produce their sour barrel and deliver it to a facility that is tied into one of the premier markets in the Permian, in order to fetch the highest netback prices available. Oil haulers are staying busy moving product to market. The Midstream company did not have to reject that sour barrel, thus increasing throughput and generating additional revenue. A win-win-win!

The comingled lines are routed to a single point where treatment occurs. Oil Haulers transport approximately 190bbls per load, and this facility receives several dozen loads per day of H2S ladened crude oil.

As the crude oil flows towards the tank battery, Q2’s Pro3 product is injected, thus ensuring that treated volume enters the tank battery array. This configuration allows for all truck lanes to offload and be treated simultaneously without pressure or flow upsets.






Q2 Technologies company data, 2001-2021.