Each oil consume causes demand pressure
Complete other rules has the photovoltaic market, an emerging industry. Here is the rule, each time the world market doubles, the prices will decrease by 20%. Each purchaser of a photovoltaic contributes, that following customers will pay less.
This are marginal costs. At 10 million barrel more offer than demand, the price will not reduce by US$200, the curve will become more flat. At 20 million less offer than demand, the price will not raise by US$400, the curve will become more flat.