By Steve Gelsi
NEW YORK (MarketWatch) -- Shares of petroleum producers rose slightly on Thursday, while natural gas producers fell. The NYSE Arca Oil Index (XOI 964.81, +1.30, +0.14%) rose 0.2% to 965. The NYSE Arca Natural Gas Index (XNG 503.96, -2.00, -0.40%) fell 0.3% to 504. The Philadelphia Oil Service Index (OSX 179.36, +8.24, +4.82%) traded about flat at 180. U.S.-listed shares of Brazilian oil giant Petrobras (PBR 35.42, +0.35, +0.10%) rose 1.2% to $35.48.
