BP, the London-listed oil and gas group, said underlying replacement cost profit rose to $8.5 billion in the third quarter, up from $2.2 billion a year earlier.
Replacement cost profit strips out the effect of price swings on inventory, and underlying figures also exclude one-off items.
The result was $2.7 billion higher than the $5.7 billion reported in the second quarter.
Higher refining margins and a stronger gas and oil trading result drove the improvement, as supply disruption in the Middle East kept prices elevated.
Brent crude averaged $96.99 a barrel in the quarter, against $69.13 a year earlier.
Operating cash flow reached $14.8 billion, almost double the $7.8 billion of a year ago.
BP used the cash to cut net debt by $8.4 billion to $13.9 billion, from $22.3 billion at the end of June.
Gearing, which measures net debt against total equity, fell to 14.8% from 22.6% in the second quarter.
Reported profit attributable to shareholders was $4.7 billion, against $1.2 billion a year earlier.
That figure was held back by $4.0 billion of post-tax impairments, largely on its transition businesses, which include Lightsource bp, its solar arm, and offshore wind.
Deepwater Horizon
Meg O'Neill, the chief executive, said BP would now prioritise excess cash to pay off its remaining Deepwater Horizon liabilities in full.
The 2010 Gulf of Mexico disaster killed 11 men.
BP agreed last week to accelerate payments to the State of Louisiana, including a $350 million settlement whose timing is still to be set.
Dividend and disposals
The company declared an interim dividend of 8.660 cents a share, up from 8.320 cents a year ago, payable on 18 December.
It said the $6 billion sale of a 65% stake in Castrol, its lubricants business, to Stonepeak, the investment firm, was expected to close imminently.
BP completed the sale of its Gelsenkirchen refinery in Germany to Klesch Group on 31 July, and plans to market its North Sea and Archaea Energy businesses.
Upstream production held at 2.2 million barrels of oil equivalent a day.
BP guided to fourth-quarter production of 2,090 to 2,230 thousand barrels a day, and a significantly lower result in its customers' business.
O'Neill said the balance sheet remained "our number one job", and that BP was "still too leveraged".
The company will set out the next phase of its strategy on 15 December.
