That depends on who's estimate you use, and whether you re an optimist or a pessimist: The values run from a low of $1.2 Trillion to a high of $2.6 Trillion.
One Bank (B of A) suggests valuations between $1.22 and $2.27 trillion - a RANGE of just over $1 Trillion.
Putting B of A's numbers into perspective - in a highly concentrated market:
B of A's price RANGE is larger than the market capitalization of the next five global energy companies combined.
B of A's low valuation is about 20% higher than the next largest company in any industry.
B of A's high valuation would represent about half the market capital of the entire global energy industry. (certeris paribus -- though they never are!)
(Disclaimer: This is not a recommendation to buy or sell any security.)