[b_t_s]

No expert but:

From day 1 OPEC has been a loose association off frenemies that occasionally manage to work together for a while when enough of them are sufficiently hurting/greedy at the same time. They break due to producer rivalries every few years.

Oil in the ground is marginally more valuable than pie in the sky. There is nearly unlimited oil in the ground, but you have to find it, extract it, and show a profit after you subtract your expenses. Each step is harder than the last. Saudi oil is like $10 a barrel to produce. You can practically dig it up with a shovel. And it's high quality...a benchmark grade that a lot of the world's refineries are set up for. Much of Venezuelas oil is deep underwater and/or garbage quality. Think huge expensive deep water oil rigs and pumping high pressure kerosene into the ground to loosen up the tar/oil sands enough to get a nasty chunky sandy sludge out of the ground that a lot of refineries can't even process. And it doesn't help that they're under sanctions and don't domestically produce a lot of the equipment they need to extract their oil. And rampant corruption. Venezuela's massive reserves have equally massive challenges turning into profitable oil production.