The roller-coaster ride of oil prices is speeding downward, carrying with it bickering members of OPEC, anxious U.S. shale oil producers and a Russia that relies heavily on petroleum revenue. With a weak global economy, the customary swing producer of oil — Saudi Arabia — has cut prices instead of cutting production, setting off a scramble on world markets. Crude oil prices have tumbled more than 23 percent since June, including a more than 4 percent drop Tuesday. Prices fell below four-year lows to wind up at $81.84 a barrel for the benchmark grade, West Texas Intermediate. A tidal wave of revenue has shifted with plunging prices. About $200 billion that would have flowed into the coffers of the Organization of the Petroleum Exporting Countries has instead remained in the hands […]