BP PLC said Monday its oil and natural-gas output fell for the fourth straight quarter and that the explosion at its Texas refinery last year will cost it $500 million more than it had anticipated, the Associated Press reports. In a trading update, BP said that production in the second quarter fell by 2.5 percent to 4.01 million barrels of oil equivalent per day, largely because of changes to its Venezuelan operations. That is down from 4.112 million in the similar period a year ago and 4.035 million in the first quarter.