Major oil traders gathered in Switzerland this week said they expected OPEC and non-OPEC producers to extend their pact to curb output in the second half of this year, providing Russia complies. “I think the surprise so far this year is how quickly shale came back on a relatively modest price rebound,” Gunvor CEO Torbjorn Tornqvist told a panel at the FT Commodities Global Summit in Lausanne. An unexpectedly quick return of U.S. shale production since OPEC and non-OPEC producers agreed in December to limit oil production has put the brakes on a rebounding oil price. After rallying to above $55 a barrel after the December agreement, crude is now trading at around $51 a barrel. “Will the agreement hold? By and large, yes. I think the rewards have been there, they (the cuts) put a floor to the market,” said Tornqvist. A committee of ministers from OPEC and non-OPEC members said on Sunday that it had agreed to review whether the global pact to limit supplies should be extended by six months. The upturn in shale output has also prompted OPEC to engage U.S. producers in talks about how best to tame the global oil glut, although Tornqvist said he did not expect the pace of recovery in shale production to be sustained.