* Q2 EPS C$0.61 vs C$0.15 yr earlier
* Overall production rises 10 pct
* Oil sands plant down for unplanned outage
* Shares up 1 percent (Adds Horizon outage details, analyst comment)
CALGARY, Alberta, Aug 5 (Reuters) - Profit at Canadian Natural Resources Ltd CNQ.TO, the country’s biggest independent oil explorer, surged more than four-fold in the second quarter on higher crude prices and a big jump in production, the company said on Thursday.
Canadian Natural also said it took its Horizon oil sands plant in northern Alberta down for about two weeks at the end of last month for unplanned maintenance, forcing it to trim its annual target for synthetic crude production.
Net income rose to C$667 million ($655.8 million), or 61 Canadian cents a share, in the second quarter from C$162 million, or 15 Canadian cents a share, a year earlier.
Adjusted profit, which excludes most one-time items, was 63 Canadian cents a share.
Analysts on average had expected earnings of 55 Canadian cents a share for the quarter on revenue of C$3.24 billion, according to Thomson Reuters I/B/E/S.
The higher-than-expected profit was due to a double-digit gain in production and lower royalties and operating costs, UBS Securities analyst Matt Donohue wrote in a research note.
Shares in Canadian Natural were up 41 Canadian cents, or 1 percent, at C$36.83 on the Toronto Stock Exchange on Thursday morning.
The company’s cash flow, a measure of its ability to fund new projects, rose to C$1.63 billion, or C$1.49 per share, from C$1.37 billion, or C$1.26 per share.
Revenue before royalties rose 31 percent to C$3.61 billion.
Canadian Natural benefited from rising oil and gas prices during the quarter. Benchmark oil prices averaged $78.05 per barrel, up 31 percent from the year-earlier quarter, while gas prices rose 14 percent to average $4.35 per million British thermal units.
For the second quarter, overall production rose 10 percent to 649,195 barrels of oil equivalent a day from a year earlier.
Total crude oil and natural gas liquids production was 443,045 barrels per day, up 21 percent from a year earlier. The company’s output of steam-driven heavy crude oil surged 53 percent to 96,000 barrels a day.
Total natural gas production was 1.2 billion cubic feet per day, down 9 percent.
Synthetic crude output at the Horizon plant averaged 99,500 barrels a day in the quarter.
However, at the end of last month, as the company was carrying out maintenance at the oil sands plant, it found more extensive pipe thinning than expected, it said. That prompted it to shut the plant down until mid-August.
The repairs are not considered technically difficult or expensive, but Canadian Natural now expects annual production to average 90,000-100,000 barrels a day. The top end of its previous forecast was 105,000 barrels a day. ($1=$1.02 Canadian) (Reporting by Jeffrey Jones and Bhaswati Mukhopadhyay; Editing by Peter Galloway)