* Q3 EBIT up 149 pct to $111 mln vs $95.3 mln seen in poll
* Raises 2012 EBITDA guidance for 4th time to about $800 mln
* Says expects strong 2013 summer season (Adds detail)
OSLO, Oct 25 (Reuters) - Norway's Petroleum Geo-Services , whose ships scan the ocean bed for oil reservoirs, raised its 2012 earnings forecast for the fourth time in less than six months as energy firms compete intensely for new oil discoveries.
Its third-quarter earnings easily beat expectations and the firm now sees 2012 earnings before interest, taxes, depreciation and amortisation (EBITDA) at about $800 million as demand for seismic data is expected to grow by more than 10 percent, it said on Thursday.
Its previous guidance from three months ago was for a full-year core profit between $750 million and $800 million, compared to the $535 million profit in 2011.
PGS, a key beneficiary of the current offshore oil exploration boom and high crude prices, said that the order book was "comfortable" with good visibility through the first half of 2013, expecting a "strong" summer season.
The boom has created a shortage for everything from rigs and seismic surveys to people, pushing prices higher and providing lucrative benefits to oil services firms.
July-September EBIT rose 149 percent to $111 million, beating the $95.3 million average estimate seen in a Reuters poll, as a result of strong improvement in margins both for PGS marine contract services and multiclient services, PGS said.
Its profit improvement programme, which targets a $50 million EBIT run rate improvement by the end of 2012, is on track with more than $40 million in savings by the end of the third quarter, the company said. (Reporting by Victoria Klesty; Editing by Balazs Koranyi)