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What else is in my sample? Does it matter?

Introduction


One of the strengths of OMMICA tests is their specificity, and lack of interferences.

This is important for testing oilfield samples, as they can be cocktails of multiple chemicals, depending on whatever treatment chemicals might have been used in the oil production process. An overview of this has already been given in previous posts; this one goes into more detail.


Many of the tests for interference were performed as a result of a customer asking, “We have X in our system, will it cause a problem with OMMICA”?


Oil production chemical testing


Over the years, hundreds of oilfield production chemicals have been tested against OMMICA. In the vast majority of cases, either there was no response in the assay, or the response could be directly correlated to the stated concentration of MEG in the chemical (for example, many corrosion inhibitors use MEG as a co-solvent in the mix).


For those reagents which did give a response, a more detailed concentration study was performed, to show at what concentration the presence of the test reagent had an impact on the assay. Generally, this was at a higher concentration than the chemical is dosed at in oil production.


Chemical classes with no effect on OMMICA:

  • Corrosion inhibitors (> 100 tested)

  • Scale inhibitors

  • Asphaltene inhibitors

  • Demulsifiers

  • Foamers

  • Defoamers

  • Kinetic hydrate inhibitors

  • Enhanced oil recovery cocktails


Chemical classes with some effect on OMMICA:

  • Biocides (some)

  • H2S scavengers

  • Oxygen scavengers


If you have concerns about any of these chemicals being present in your OMMICA samples, please contact us; it’s likely that the level present will be lower than that which causes an issue.


Salts


Many oilfield samples will also contain seawater, which contains significant levels of sodium chloride, as well as many other salt species. Recipes for synthetic brines from different regions of the world can be obtained, and were tested early on in the development of OMMICA, to ensure that they did not cause an issue with the test (for example forming a precipitate which could give a falsely high result).


Of all the salt species tested, the only one likely to cause issues at levels that may be found in real samples is calcium salts (which may create a precipitate): if you suspect these are present at high levels in your sample, please contact us for advice, as there is a simple way of managing the issue.  


Example

A customer who was interested in using the OMMICA MEG kit to test the performance of their MEG regeneration plant contacted us to check that the salts they knew they had in their system wouldn’t cause a problem. This was a different cocktail than was present in seawater-based brines. Again, we were able to show that none of the species they had present would be a concern at the working range of the assay.


Related species


We have also tested the effect of closely related species in the assay, for example testing ethanol in the methanol assay, as well as cross-contamination (e.g. what happens if you have methanol in your MEG assay). In most cases there is no issue, or none if there is below a specified level: see below.


Methanol analysis:

  • Ethanol up to 10x the methanol concentration: no issues

  • MEG up to 5%: no issues


MEG analysis:

  • Methanol up to 1000 ppm: no issues

  • TEG (Triethylene glycol, also used for gas dehydration, in place of MEG): no issues

  • DEG (Diethylene glycol): no issues up to 1%

  • MDEA (N-methyldiethanolamine, may be in MEG dehydration systems); no issues up to 1000 ppm as analysed

 

Summary


As can be seen from this information, the OMMICA tests are very powerful at analysing the species of interest without interference from other chemicals in the sample mixture.

If you have any concerns about what might be in your samples, please contact us at support@ommica.com for further information.

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