English to Russian Tech/Engineering Petroleum Eng/Sci

In calculating by-product crediting in olefin production costs, the market price or fuel equivalent value of the respective by-products prevailing in the region is used in the unit cost crediting calculation. Namely, the C4 stream is valued equal to the butane price per ton on the open market, pyrolysis gasoline to the naphtha procurement price per ton, and hydrocarbon gas/liquid to the procurement price per MMBtu.

On the other hand, in a situation where the crude oil price exceeds $100/b, credit units for the C3 and C4 fractions co-produced via cracking of ultra-low cost ethane trend higher because they are linked with crude oil, and a phenomenon occurs whereby the variable cost for ethane-based ethylene is zero or even lower.