Angola announced Thursday that it's leaving the OPEC oil producers cartel, coming after it battled with the group over lower production quotas this year. Diamantino de Azevedo, the African nation's oil minister, said Angola “does not gain anything by remaining in the organization,” according to state news agency Angop. The country joined OPEC in 2007. Disagreements over lower oil quotas for some African countries, including Angola, led to an usual dayslong delay to OPEC's November meeting, where the group, along with allied producers led by Russia, decide how much oil to send to the world. At the meeting, Angola's production...