The oil companies were leading the rise on Wednesday afternoon, with Tullow Oil, Essar Energy and BP among the better performers on the blue chip index, helped by a rising oil price.BP rose after drilling results confirmed a significant resource extension of The Mad Dog Field complex in the Gulf of Mexico.Imperial Tobacco fell after Goldman Sachs downgraded it from buy to neutral. The cigarette maker was removed from the stockbroker's pan-European buy list and downgraded it target price from £24 to £21.90. Advertising giant WPP was heading north after it acquired market research technology firm Global Market Insite (GMI) for an undisclosed sum. GMI will be aligned with Lightspeed Research, a division of WPP's wholly-owned information, insight and consultancy group Kantar, which provides global online research panels and products. Moving lower were mining peers Randgold Resources and Fresnillo, as gold and silver prices took a hit, falling 3.15% and 2.5%, respectively, in the afternoon.FTSE 100 - Risers Wolseley (WOS) 1,607.00p +6.49%Tullow Oil (TLW) 1,147.00p +5.62%Essar Energy (ESSR) 254.20p +5.48%Lloyds Banking Group (LLOY) 32.44p +5.48%GKN (GKN) 185.00p +3.99%Weir Group (WEIR) 1,822.00p +3.76%Antofagasta (ANTO) 1,290.00p +3.70%Burberry Group (BRBY) 1,319.00p +3.69%WPP (WPP) 613.50p +3.63%Smiths Group (SMIN) 961.50p +3.55%FTSE 100 - FallersImperial Tobacco Group (IMT) 2,062.00p -2.04%Randgold Resources Ltd. (RRS) 6,825.00p -1.66%Fresnillo (FRES) 2,041.00p -1.11%Rexam (REX) 336.80p -0.91%Diageo (DGE) 1,211.00p -0.74%Hargreaves Lansdown (HL.) 480.10p -0.70%Resolution Ltd. (RSL) 251.00p -0.36%Tesco (TSCO) 374.20p -0.15%Morrison (Wm) Supermarkets (MRW) 291.10p -0.10%NR