Case
Studies

Surfactant chemistry is widespread through chemical treatment programs in oil and gas infrastructure. Aggregates of surfactant, known as micelles, are found when concentrations exceed the formulation CMC meaning micelles are a commonly found analyte in the industry.

Our case studies detail how micelles can be used in optimising corrosion inhibitors, tracking biocide slugs and which factors can influence the concentration of these key protective molecules.

Areas of Interest
Image

Location: Onshore European Gas Field

Date: 2018

Assessment Type: CoMic™ Injection Optimisation

Background

An onshore European asset was undergoing a change in downhole corrosion inhibitor formulation, substituting a hydrocarbon soluble inhibitor for a more water soluble alternative. The chemical was injected in batch doses and timed to allow the chemical to disperse within the system before the subsequent injection, the operator wanted to ensure full system dispersion between doses.

CoMic™ was selected as a management tool due to the ability deploy on-site, the quick processing of data and the ability to rapidly change and optimise system properties to ensure constant micelle presence within the system and inform system management.

Testing

CoMic™ was employed to measure the micelle content of samples to determine inhibitor levels between injections. The existing dosing regime was tested first. The results showed that the corrosion inhibitor levels dropped significantly (no micelles were detected) before the next injection cycle began. This indicated that during this time, there was an opportunity to better protect the system.

The operator then trialled alternative injection regimes, including altering pump capacity, injection duration and time between injections, in order to identify a regime where micelles were consistently observed throughout the injection cycle.

Testing of the final regime with CoMic™ confirmed that micelles were detected during all time points in the injection cycle. This indicated that the new regime offered good availability of inhibitor to provide optimal corrosion protection.

Summary

CoMic™ provides an indication of inhibitor availability. In this field deployment, changes in the system were rapidly detected, making it the ideal tool for on-site chemical optimisation. CoMic™ was used to establish a baseline for existing dose rates, and demonstrate the response to dosage changes. This produced a tailored recommendation based on field conditions, and gave confidence that the system’s chemical management was optimal.

Download Case Studies


As some of the information relating to these examples is commercially sensitive, we have retained the anonymity of our clients in relation to the case studies.

To discuss how CoMic™ can be of use in protecting your assets, please get in contact with us.

Contact Us

Image

As some of the information relating to these examples is commercially sensitive, we have retained the anonymity of our clients in relation to the case studies.

To discuss how CoMic™ can be of use in protecting your assets, please get in contact with us.

Contact Us

Biocide Surfactant Mapping
Image

Location: USA

Date: 2016

Assessment Type: Micelle facilitated biocide mapping to inform dose

Background

Certain types of biocides, such as those containing benzyl quaternary amines, have a surfactant component and can form micelles when present in concentrations above the CMC. The study investigated whether biocide micelles could be detected in field samples and used to ‘map’ the biocide across a large US onshore facility.

If so, it would allow the operator to understand the path of the chemical through the system and inform dosing.

Testing

Surfactant containing biocides were injected from Unit A on the first and third days of testing; biocide 1 (1000 ppm) on day 1 and biocide 2 (300 ppm) on day 3. An additional injection of biocide 2 was injected to Unit D on day 3.

Biocide 1 was a low surfactant formulation (5%) while biocide 2 was high in surfactant (~60%). Water was taken from the system at varying times during the test period. The following map and graphs show the testing of injection waters from Units A to H through the branch line for biocides 1 and 2.

Readings taken the day prior to batch dosing (Pre) showed no micelle signal indicating untreated water. As samples were taken from the slug front, mid and late the micelle signals are observed to increase as the slug transited the sample point.

Solid lines represent samples connected by timing at the same sample point, while broken lines represent transit between sample points. As can be seen, the micelle signal can be used to trace the passage of surfactant based biocide through a system, even at low concentrations of surfactant.

Unit H was measured around the expected mid-point of the slug but showed low micelle signal. This represents a loss of chemical between Unit G outlet and the sample point of Unit H.

The 'kill dose' of biocide 1 was approximate to the CMC of the chemical, TraxBio™ therefore provided reassurance that a sufficient dose of biocide was present at all sample points along the test line.

In a similar fashion, Biocide 2 was traced through Unit G by time on the third day of testing. The results, again, provided confidence that biocide was transiting the system in sufficient dosage. Time monitoring of the samples allows estimation on sample residence times to also be calculated.

Summary

  • On-site testing afforded near real-time results to be achieved
  • Testing showed the path of travel of the biocide through the system and whether it was present at the kill dose throughout the system
  • Areas requiring additional dosing were highlighted – alerting the operator to a potential biofouling risk

Download Case Studies


As some of the information relating to these examples is commercially sensitive, we have retained the anonymity of our clients in relation to the case studies.

To discuss how TraxBio™ can be of use in monitoring your biocide dosage, please get in contact with us.

Contact Us

Image

As some of the information relating to these examples is commercially sensitive, we have retained the anonymity of our clients in relation to the case studies.

To discuss how TraxBio™ can be of use in monitoring your biocide dosage, please get in contact with us.

Contact Us

Chemistry of Micelles
Image

Assessment Type: Effect of production solids on micelle populations

Background

Surfactant-type corrosion inhibitors are designed to adsorb to the internal surface of pipelines, forming a passive hydrocarbon layer to prevent access of corrosive liquid to the pipe surface. When dosed at a high enough concentration, the surfaces in the system will become saturated and inhibitor will accumulate in the production fluids forming aggregates known as corrosion inhibitor micelles. These form at the Critical Micelle Concentration (CMC).

Solids originating from formation residues, corrosion by-products and scale formation can all provide secondary binding sites for corrosion inhibitor, leading to decreased availability and implications for system protection.

CoMic™ and TraxBio™ technology detects micelles in the water phase of oilfield samples to provide information on inhibitor or biocide availability. In this example, micelle detection was used to determine the losses of surfactant to various commonly observed production solids.

Testing

The CMCs of four commercially formulated corrosion inhibitors were determined to be below 100 ppm. Separate 100 ppm corrosion inhibitor solutions in 1 M NaCl were prepared and a 20 mL sample of each inhibitor solution was transferred to a vial charged with a known mass of the test solid, sealed and gently agitated at hourly intervals for 5 h. The solutions were allowed to equilibrate for a further 15 h before analysis with CoMic™.

Results

All chemicals showed varying losses of surfactant chemicals to the solids tested. Losses were inhibitor and solids dependent, with inhibitor 1 showing the least reduction in micelle signal with solid mass.

Summary

The testing shows that solids in systems can act as a sink for corrosion inhibitor, reducing availability and presenting a possible corrosion risk. Optimal chemical management of a system should consider this impact. CoMic™ can provide a useful laboratory or field tool to assist asset integrity managers and production chemists.

Download Case Studies


To find out more about micelles and their applications to CoMic™ and Traxbio™ technologies, please get in contact.

Contact Us

Image

To find out more about micelles and their applications to CoMic™ and Traxbio™ technologies, please get in contact.

Contact Us