DougR, you give OPEC too much credit. The oil-producing nations all go along with their actions to stabilize the market. OPEC stepped out of this position in 1973 when they instituted embargos because of the U. S. support of Israel, but since then, stability is their object.

The three countries which supply the most petroleum to the United States are Canada, Saudi Arabia and Mexico, in that order.
Neither Canada nor Mexico are members, but oil producers all go along.
OPEC members do account for about one third of oil production.
The strongly rising demand, from China, India, and the growing industrialization of Korea, Malaysia, Australia and other nations, as well as U. S. demands for increased production are putting pressure on OPEC controls. It is hard to predict just what will happen.

The Arab Emirates and Saudi Arabia itself, are industralizing. The oil will not last forever, and increased sales mortgage their future

United States was an OPEC member via the Coalition Provisional Authority when it formally occupied Iraq, 2003-2004. Iraq has retained its membershio in OPEC.
OPEC is willing to take on new member states, and several have resigned for various reasons.

Of course, if the U. S. has viable prospects, they should be explored unless disruptive of the environment. There are prospects offshore or in the oil shales, but the former are unknown as to volumes, and the latter require $150/bbl approx. for them to be viable. The offshore areas under U. S. jurisdiction need approval from Congress, and development of regulations for their control.

No matter what is found, I do not expect to see cheap oil again. The pressure of demand is too great.