* Sees 2013 revenue of $970 mln-$1.05 bln vs $931 mln in 2012
* Sees 2013 multi-client investments of $530-600 mln
* Shares rise over 7 pct (Adds analysts, shares, Dolphin comments, detail)
By Victoria Klesty
OSLO, Jan 8 (Reuters) - Seismic surveyor TGS-Nopec, which scans the sea floor for oil and gas deposits, beat 2012 revenue expectations and forecast growth of up to 13 percent this year as oil firms ramp up spending on exploration.
Shares in the Norwegian company rose over 7 percent on Tuesday after it also said it would step up investment to help meet growing demand.
Oil companies are spending more on exploration as prices have remained high despite gloomy economic conditions.
TGS's smaller rival, Dolphin Group, predicted on Tuesday its 2013 revenues would leap between 40 and 50 percent.
"It is a very good outlook, the guidance is solid," said Nordea Markets analyst Joergen Andreas Lande of TGS' prospects.
"First, the better (than expected) fourth quarter numbers are very positive, and second, increasing investments. They are expanding on higher demand."
TGS said it expected revenue this year of between $970 million and $1.05 billion.
Its 2012 net revenue came in at about $931 million, above its target of $870-910 million, with fourth-quarter revenue at about $280 million, up 55 percent from the same period in 2011.
TGS shares, which have surged 38 percent over the past year, were up 7.2 percent to 193.4 Norwegian crowns at 0855 GMT.
"We expect 2013 consensus on revenues to increase by at least 5 percent given management's recent record of issuing conservative guidance," Danske Markets analyst Jo Henrik Eriksen said in a note to clients.
Last year, TGS raised its guidance three times throughout the year.
TGS said it expected to invest between $530 million and $600 million in 2013 in its multi-client library of survey data - information it sells to a variety of customers.
Multi-client scanning typically generates higher profit margins than contract seismic exploration, but comes with added risks since it cannot be sure it will be sold at all.
TGS's investments in 2012 reached $494 million.
The firm saw "strong client interest to invest in both new and existing data," and said its vessel capacity remained adequate to execute its plan. It does not own its own vessels but instead leases them.
TGS is set to release its final results on Feb. 7.
Dolphin Group said it expected 2013 revenue to top $300 million, and that operating margins would improve.
It noted high exploration activity among oil firms in northern Europe, South America and Africa. (Additional reporting by Henrik Oliver Stolen; Editing by Mark Potter)