Tullow Oil is seen as a likely takeover target (MarketWatch) — Royal Dutch Shell’s megabuy of smaller rival BG Group has ignited speculation that the takeover could usher in an M&A rush in the oil and gas sector — and the big question is, who’s next? Share-price moves on the London Stock Exchange are already signaling what investors are thinking, with rises for some smaller oil companies on hopes lucrative offers could come their way. That’s echoing what happened to BGBG., +0.26% BRGYY, -1.39% Wednesday morning, when its shares soared almost 40% on the news that Shell RDSB, +0.20% RDS.B, -0.70% has agreed to buy the company for 47 billion pounds ($69.6 billion). “This could mark the beginning of an M&A rave, much like the one we saw in the late 1990s where all manner of small oil-and-gas stocks were snapped up by larger ones — leading to the group of heavyweight oil majors we know so well today, in the likes of Exxon Mobil, BP, Chevron, and [...] Royal Dutch Shell,” said Augustin Eden, research analyst at Accendo Markets, in a note.Tullow Oil could be up for grabs Oil and gas exploration company Tullow Oil PLC TLW, -0.23% is considered by analysts to be a likely takeover target, and its shares rallied 9% in London trade. Also on the energy M&A radar are EnQuest PLC ENQ, +1.27% up 5.2%, Premier Oil PLC PMO, +0.33% gaining 2.5%, and Gulf Keystone Petroleum Ltd.GKP, +2.43% rising 3.3%. All four suffered the same fate after oil futures slumped: Their share prices have dipped more than 50% since last summer. “In the case of Tullow Oil, it would make a good acquisition because they are already in parts of the world that could prove exciting going forward in terms of exploration,” said Keith Bowman, equity analyst at Hargreaves Lansdown. “So instead of suffering that cost themselves from scratch, [oil majors] can replace the cost of exploration with the cost of a potential takeover.” Among bigger names, BP PLC BP., +0.40% BP, -0.94% is being tagged as a potential target for one of the U.S. oil majors — and that helped lift its shares 3.2% in Wednesday’s trade. The strategy of using a takeover as a way of scooping up attractive assets was a significant factor in the Shell-BG deal. Analysts pointed to BG’s deepwater assets in Brazil and its liquefied natural gas portfolio as key attractions for Shell.Potential shopping spree So which of the oil giants could be looking for prey? Bowman said it’s probably too soon for Shell to go shopping again, but noted there’s already speculation that some of its rivals may be on the lookout for a good deal. Total SA FP, +0.39%TOT, -0.76% and Statoil ASA STL, -0.07% are among the major oil companies in Europe, while Chevron Corp. CVX, +0.27% and Exxon Mobil Corp. XOM, -0.04% are Shell rivals in the U.S. “It’s not a complete surprise, and we’ve seen elements of this in the past. The oil industry has some record of consolidation when energy prices have been falling,” Bowman said. Consolidation among energy majors got a start back in November, when oil-field-services giant Halliburton Co. HAL, -0.17% announced a merger with rival Baker Hughes Inc. BHI, -0.02% in a deal seen as helping both contend with falling oil prices.