* Q2 oper profit C$934 mln vs C$1.25 bln a year ago
* Q2 oper profit per share C$0.62 vs estimate C$0.63
* Q2 cash flow per share C$1.49 VS C$1.51 a year ago
* Q2 oil sands production falls about 11 percent
July 31 (Reuters) - Canada's Suncor Energy Inc posted a second-quarter profit that missed analyst expectations by a penny as earnings were affected by factors including the precautionary shutdown of third-party pipelines due to flooding in northern Alberta.
Net income for the quarter was C$680 million ($661.5 million), or 45 Canadian cents per share, up from C$324 million, or 21 Canadian cents, in the second-quarter of 2012, Canada's largest oil and gas company said late on Wednesday.
Operating profit, which excludes most one-time items, fell 25 percent to C$934 million, or 62 Canadian cents per share, down from C$1.25 billion, or 80 Canadian cents a share, in the year-earlier quarter. The result was below the average analyst forecast of 63 Canadian cents per share according to Thomson Reuters I/B/E/S.
Suncor's cash flow, a glimpse of its ability to pay for new projects, fell 4 percent to C$2.26 billion, or C$1.49 per share, from C$2.34 billion, or C$1.51 a share.
Production from its oil sands operations fell about 11 percent to 276,600 barrels per day, while total output from its operations in North America, the North Sea and north Africa was about 8 percent lower at 500,100 barrels of oil equivalent per day.
The company said operating profit was impacted by planned maintenance in oil sands and refining and marketing segments.
Also, Suncor said it faced additional production constraints in oil sands due to unplanned third-party outages, including the precautionary shutdown of third-party pipelines in response to flooding in northern Alberta.
Suncor shares closed at C$32.46 on the Toronto Stock Exchange on Wednesday. The shares have risen 5.9 percent over the past 12 months, against a rise of 1.1 percent in the exchange's main energy index.