English Tech/Engineering Petroleum Eng/Sci oil production

I have closed my previous question because it was errant.
I have come across the term "Pay-check" in a technical text regarding petroleum production and production measurement.

The sentence is:
• Current day dry oil Pay-Check allowable deviation

Later the text shows that "Pay" and Check" are separate terms. Therefore I am repeating the question for the 2 different terms.

Any suggestions? I haven't found any answer searching in specific dictionaries.

Thanks in advance.