NEW YORK (Reuters) - Exxon Mobil Corp topped its own record for the biggest U.S. quarterly operating profit and Royal Dutch Shell Plc earnings beat market forecasts on Thursday, helped by high oil prices and fatter refinery margins.

A customer fills up at a Mobil gas station in Medford, Massachusetts, April 30, 2008. REUTERS/Brian Snyder

But both Exxon and Shell said their quarterly oil output fell, in part from damage caused by Hurricanes Gustav and Ike, which swept through the Gulf of Mexico during the quarter.

U.S. oil prices averaged about $118 a barrel in the third quarter, more than $40 higher than the year-ago period. They had peaked above a record $147 in early July before turning and falling by nearly 60 percent over the next three months.

That decline, coupled with knock-on effects of the credit crunch on oil and gas producers, prompted a few more U.S. oil services companies to cut 2009 spending forecasts on Thursday.

Exxon and Shell posted strong performances in refining, which benefited as the falling crude oil price trimmed costs, even as demand for gasoline shrank, analysts said.

Gene Pisasale, senior energy analyst at PNC Capital Advisors, called Exxon’s U.S. refining profits a positive, but said it needed to focus on boosting oil and gas output.

“They need to be more aggressive with the drill bit. ... That’s going to be the focus going forward,” he said.

The global economic slump has prompted energy experts to pare back oil demand forecasts in recent months, and the oil price declines have forced many companies, such as Hess and Suncor Energy, to rein in spending on projects.

Yet Irving, Texas-based Exxon said it planned to stick to its spending plans of $25 billion this year as it maintained its strong financial position despite the economic turmoil.

Smaller rival Marathon Oil Corp said rising production and improved refinery margins helped it more than double profit in the quarter, but it cut planned 2009 spending by more than 15 percent because of the current business environment.

Exxon’s earnings jumped 58 percent from a year ago to $14.8 billion, and operating profit climbed 42 percent to $13.4 billion, easily topping the previous U.S. record it set in the second quarter at $11.7 billion.

Exxon’s majority-owned Imperial Oil Ltd, Canada’s top oil company, also had a strong quarter.

Shell’s profit rose 71 percent to $10.9 billion, topping analyst forecasts, but its shares slipped as investors focused on the Anglo-Dutch major’s 7 percent drop in oil and gas production.

Shell also said Chief Financial Officer Peter Voser would take over from Jeroen van der Veer as CEO next July.

A decline in oil futures prices that cut into a rally early this week pushed Exxon shares down 2.5 percent, after early gains, and Shell fell 4.1 percent. Marathon jumped 6.3 percent.

SERVICE SECTOR SEES SLOWDOWN

U.S. oil services company BJ Services Co, while posting a rise in profit on Thursday, foresaw weaker activity by oil and gas producers weighing on its future earnings. It cut fiscal 2009 capital spending plans to a range of $550 million to $575 million, down from $600 million in 2008.

Rival Cameron International Corp, alongside a solid third-quarter performance, also said its 2009 capital expenditure would fall.

“When you look at the kind of capex we spent the last couple of years, if you make the assumption that we’re pretty much where we need to be on capacity given the outlook, you’ll probably see capex come down a little bit,” Chief Financial Officer Charles Sledge told analysts on a conference call.

That dimmer outlook was echoed by driller Patterson-UTI Energy, which said the number of rigs hired by energy companies to search for oil and gas was likely to shrink through the end of the year.

Patterson-UTI posted a rise quarterly profits of more than 10 percent, while contract driller Pride International Inc saw its profits surge.

Pride shares jumped 13 percent, Patterson-UTI shares rose 9 percent and Cameron was up 8.8 percent, while BJ Services fell less than 1 percent.

India’s Oil and Natural Gas Corp reported a 5.7 percent drop in quarterly profit on Thursday, missing market expectations as its subsidy burden grew.

ONGC, accounting for 78 percent of India’s oil and gas production, must sell oil from its domestic output at mandated discounts to state-run refiners to keep retail prices low.