British oil major BP ( BP.L ) lifted the outlook for its core oil and gas divisions on Tuesday, saying it would be able to balance its books with crude prices as low as $35 to $40 a barrel by 2021 thanks to its tough spending cuts. BP said its upstream business, which includes its main oil and gas production fields, is expected to generate free cash flow of $13 billion to $14 billion by 2021, nearly double an outlook presented last year of $7 billion to $8 billion by 2020. The refining and marketing business, known as downstream, is expected to generate $9 billion to $10 billion of free cash flow by 2021, BP said. The oil major, which was forced to raise billions of dollars from asset sales to pay for the […]