The oil market actually has sub markets that break down by region and the type of crude that is being traded. Not all crude is created equal and there are different types of refineries that are designed to refine the different types of crude.
For example, a refinery that refines light / sweet crude won’t take the heavy stuff. Which is why places like North America export a lot of their domestic stuff. North America has a lot refineries looking for light crude, but pulls a lot of heavy stuff out of the ground.
It doesn't have to be an outright ban. You could have tariffs on imported oil, subsidies for domestic oil production, or loosened regulations that make domestic production less expensive. Reducing oil use is important, but so is reducing reliance on foreign oil. While the former also helps accomplish the latter, increased domestic oil production could still be beneficial.
(I generally think that international trade is a net benefit, but there's a lot to be said for avoiding dependence on not-so-friendly foreign governments for the supply of economic essentials.)