At least in the US, oil production is most certainly a competitive commodity market. Like lumber, buyers are constantly seeking the lowest price and sellers are seeking the highest price. Always, every second. You can see this on the commodities boards.

The question of supply is a separate question. No American major is curtailing production to increase price. None of them have that much market leverage. I assure you, if the oil companies (both majors and juniors) thought the capex would pay, they’d make the investment. But two years of high prices cannot justify the cost of a new oil rig with an eight year projected payback. Particularly when the party in power is explicitly promising to outlaw their business model. That means when demand surges as we saw the last couple years, there will be little surge capacity to respond and prices will increase.