BUZZ-Oil and gas companies: Oil prices fall on worries of oversupply

** Oil and gas companies shares down 1-6 pct premarket

** Brent crude oil prices slipped below $59 a barrel after another big weekly build in U.S. crude inventories and a possible rise in Saudi output stoked worries about oversupply

** Brent crude down 2.3 pct at $59.14 per barrel at 06:55 a.m. ET; U.S. crude down 3.6 pct at $50.28 per barrel

** Oil producers: Whiting Petroleum Corp (NYSE: WLL - news) down 5.8 pct, Oasis Petroleum (NYSE: OAS - news) 4.3 pct, Statoil ASA (LSE: 0M2Z.L - news) 3.2 pct, Total SA (Paris: FR0000120271 - news) 2 pct, ConocoPhillips (NYSE: COP - news) 1.7 pct

** Royal Dutch Shell Plc (Xetra: R6C1.DE - news) shares down 1.3 pct, Chevron Corp 1.1 pct, Petrobras 1 pct, BP Plc 1 pct

** Oilfield services companies: Schlumberger Ltd down 1.8 pct, Halliburton Co 1.9 pct, Denbury Resources (NYSE: DNR - news) Inc down 2 pct, Basic Energy Services Inc (NYSE: BAS - news) 2.2 pct

** Contract drillers: Seadrill Ltd down 3.4 pct, Transocean Ltd (LSE: 0QOW.L - news) 1.9 pct, Diamond Offshore Drilling Inc (NYSE: DO - news) 2.6 pct, Nabors Industries Ltd (NYSE: NBR - news) 2 pct, Ensco Plc (NYSE: ESV - news) 2 pct