Salamander Energy's share price rose 10.27 per cent to 205.10p on Monday as the oil and gas company announced that oil had been discovered at the first well in its multi-well programme.A combined 40m of net oil and gas pay was identified in the well - known techniclly as the South Kepaci-1 DIR/ST well, the group reported.Centamin, the Egypt-focused gold mining company was another riser on Monday with its share price having risen 6.87% to 64.55p. This came following a presentation delivered to analysts last Thursday in which the group said it was targeting a 40% rise in gold production at its Sukari gold Mine. Market chatter today suggested that a decision over the validity of its flagship Sukari mine contract is imminent - Centamin plummeted in late-October on concerns that it could lose the mining contract.Essar Energy's share price rose 2.64% to 143.90p on Monday, two weeks after the company's Indian subsdiary, Essar Oil, posted strong results for the third quarter of the year. FTSE 250 - RisersSalamander Energy (SMDR) 205.10p +10.27%Centamin (DI) (CEY) 64.55p +6.87%Perform Group (PER) 390.00p +3.17%Essar Energy (ESSR) 143.90p +2.64%Workspace Group (WKP) 333.50p +2.30%Sports Direct International (SPD) 411.80p +2.21%Oxford Instruments (OXIG) 1,752.00p +2.16%Regus (RGU) 123.60p +2.15%Ted Baker (TED) 1,190.00p +2.15%Telecom Plus (TEP) 984.50p +2.02%FTSE 250 - FallersRedrow (RDW) 180.30p -5.50%Lonmin (LMI) 364.10p -4.21%Carillion (CLLN) 297.40p -3.79%Ferrexpo (FXPO) 260.70p -3.69%IP Group (IPO) 123.50p -3.52%African Barrick Gold (ABG) 354.50p -3.14%JD Sports Fashion (JD.) 742.50p -2.94%Laird (LRD) 227.10p -2.87%Barratt Developments (BDEV) 218.10p -2.81%National Express Group (NEX) 205.00p -2.75%MF