Shares in oil and gas explorer and producer Regal Petroleum jumped after it said production at its SV-58 Well in Ukraine had doubled since its last announcement in January.The well is now producing 800 barrels of oil equivalent per day (boepd), while Regal's total production in Ukraine is 2,537 boepd.In Romania, Regal has completed the acquisition and processing of 104.7km2 of 2D seismic in the Barlad exploration concession.