* Q2 op. profit C$0.19/shr vs. C$0.39 expected

* Cash flow/shr C$0.71 vs C$0.90 expected

* Miss blamed on refining

* Shares down 5.1 pct

(Recasts to add details, comments; updates shares)

By Scott Haggett

CALGARY, Alberta (Reuters) - Shares of Cenovus
Energy Inc fell more than 5 percent Thursday after
the oil sands producer missed analyst forecasts due largely to
weakness in its refining segment.

Cenovus. Canada's No. 3 independent oil company, reported
an 8 percent rise in quarterly profit, helped mainly by higher
oil sands output and one-time gains. It said it was on track to
meet its production and cash flow targets for the year.

But the company's operating profit, which removes most
one-time items, was much weaker than expected, coming in at
C$142 million ($136 million), or 19 Canadian cents per share,
down 72 percent from C$512 million, or 68 Canadian cents, in
the year-earlier quarter.

That was well below the average analyst estimate for the
measure of 39 Canadian cents per share, according to Thomson
Reuters I/B/E/S.

Cash flow, a closely watched measure of a company's ability
to afford ambitious expansion plans, was also shy of
expectations, dropping 43 percent to C$537 million, or 71
Canadian cents per share, below the 90 Canadian cents per share
expected.

"The main source of the miss is likely refining, which
reported a $24 million loss," Peter Ogden, an analyst with
National Bank Financial, said in a research note.

"With underwhelming (second-quarter) results today, this
may remind the Street about the volatility of refining and its
potential liability to quarterly results."

Cenovus, which was spun off last year from Encana Corp
, co-owns two U.S. refineries with ConocoPhillips
. It said maintenance work cut throughput at the sites
and it processed oil bought at high prices in the first quarter
for less than expected as crude prices declined during the
April to June period.

Cenovus also co-owns two steam-driven oil sands projects in
Alberta with Conoco -- Foster Creek and Christina Lake -- where
output climbed a combined 42 percent in the quarter.

Conventional oil and gas production fell 8 percent to
70,000 bpd, as its fields aged and some properties were sold.

Cenovus shares fell C$1.52 to C$28.45 midday on the Toronto
Stock Exchange.

The company's revenue rose 14 percent to C$3.2 billion.

($1=$1.04 Canadian)
(Additional reporting by Bhaswati Mukhopadhyay; editing by Rob
Wilson)