* Q2 oper EPS C$0.81 vs C$0.72 estimate
* Q2 net income down 40 pct to C$333 million
* Q2 cash flow up 18 pct to C$2.34 billion
* Q2 total upstream production rose 18 percent to 542,400 boepd
July 24 (Reuters) - Suncor Energy Inc, Canada's No. 1 oil producer and refiner, posted a second-quarter operating profit that beat analyst expectations, helped by increased production and higher refinery margins.
The company said operating profit, which excludes most one-time items, rose 28 percent from the second quarter of 2011 to C$1.26 billion, or 81 Canadian cents per share, from C$980 million, or 62 Canadian cents per share.
The result beat the average analyst estimate of 72 Canadian cents for the measure, according to Thomson Reuters I/B/E/S.
Suncor, which also has conventional oil and gas operations in Canada, North Africa and the North Sea, as well as refineries in Canada and the United States, said its cash flow rose 18 percent to C$2.34 billion.
It reported a net income of C$333 million, or 21 Canadian cents per share, down 40 percent from C$562 million, or 36 Canadian cents.
Suncor's total upstream production rose 18 percent to 542,400 barrels of oil equivalent per day (boepd) from 460,000 boepd a year earlier.
Refinery utilization averaged 94 percent in the second quarter of 2012, and refineries in Western North America ran at full capacity, the company said.