Economics is considered simpler than arithmetic.
The realities of the oil market drew the attention of oil producers that such a by-product as tank sludge is now worth its weight in gold and the question of maximizing the extraction of oil from tank sludge is very relevant. If we take the current price of oil 1500ue, then 400-700 kg of oil extracted from the tank sludge is, for a minute, 600-1050ue of additional profit for each ton of tank sludge.