Royal Dutch Shell reported a 20 percent drop in second-quarter earnings on Thursday as higher costs, exploration charges, exchange rate effects and challenges in Nigeria took their toll.
"I am disappointed with the results," Chief Executive Peter Voser told CNBC on Thursday.
On a current cost of supply (CCS) basis, earnings came in at $4.6 billion versus a forecast of $5.75 billion. That compared with $5.7 billion in the second quarter of 2012.
Shares of Shell closed down around 4.5 percent on Thursday.
Voser said the company was committed to Nigeria, despite the problems in the west African country.
"Oil theft and disruptions to gas supplies in Nigeria are causing widespread environmental damage, and could cost the Nigerian government $12 billion in lost revenues per year," Shell warned on Thursday.
"In the last few months we lost 100,000 barrels and a hundred of tonnes of LNG because of a blockade of our ships and there is vast environmental devastation because of this sabotage," Voser told CNBC.
"We will play our part, but these are problems Shell cannot solve alone," Voser said in a statement.
He said the company, and the oil industry in general, was not threatened by the energy "revolution" in the U.S. which could bring oil prices down.
"I would still see a high-ish type of oil price going forward irrespective of the light tight oil revolution in North America - which so far has not taken off outside of North America just to be clear."
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