[Alnan]

Are there any options to mark (i mean chemical marking) the crude oil of specific company before refining to be sure, that after reprocessing in other country (as some countries do not have oil refining factories) we have obtained the products exactly from initial crude oil of this company in order to avoid its replacing??

[phth]

My guess is you gotta find some chemical that creates a near perfect azeotropic point with the octanes.  If it goes through solid phase purificaiton also this might put an additional constraint on the polarity of the chemical.

[Arkcon]

I'd say this is unlikely, but I'd wait for some experts on this board to be sure.  Briefly, the component profile of a sample of crude oil can be used to determine which oil fields it may have come from.  But once refined, the products lose that profile.  Unless you want to radio-label the refined component, but that's be expensive to do in bulk, and really overkill in terms of safety to the likely need.

I suppose you have a reason, but if crude oil is being refined into gasoline, or kerosine, or some other component, the end product is the same regardless of source.   I assume you have some reason for tracking the source petroleum, and how it gets used, but I don't  see a feasible way to do that with output products.

[Alnan]

 Arkcon and phth, Thanks for your very interesting answers

[Enthalpy]

I'm pretty sure this is already done, because it's a common desire of the oil industry.

Just one example is the phytane-to-pristane ratio. They differ by one -CH₂- so distillation won't change the ratio too much, and it's characteristic of the oil well. These two molecules will land in the Diesel oil mainly but are still observable in kerosene and heating oil.

If you measure a dozen of such ratio in your crude oil, of molecule pairs (or more) that have the same boiling point, and pick you set of molecules over the end product spectrum so you get two or three marker sets in every cut, you know from which well the cut was obtained.

If you could observe enantiomer ratios, and provided these bear some information (oil is a result of biological processes after all), this would be nearly perfect: very costly to fool.

Other techniques were thought, these ones by adding some markers, but (1) it needs some action (2) you aren't sure a few markers will get to each cut. Consequently, it's more a technique for already destilled products.

You would need to keep secret what markers you check, because people willing to fool you would easily rebalance the checked amounts if they know which ones.

[curiouscat]

The fundamental question is why? One molecule of decane is exactly fungible with another. And the process of refining anyways transforms molecules & molecular ratios in drastic ways.

What you want to do is law stringent specs on the product that actually comes back. And those tests we already have in abundance: BP, density, vapor pressure, calorific value, residue content, ash content, Total Sulfur, acidity, etc.

Also, unlike the pharma or food industry refining operations are almost all continuous. So even if you wanted to, batch integrity & identity would be extremely hard to maintain. Unless you maintained separate tanks, & washed  / drained equipment before changing source crudes you are going to have some contamination.