Greka Drilling Share News (GDL)

A profit warning from blue-chip oilfield services group Petrofac rattled the oil services, equipment and distribution sector in London on Monday, with stocks falling by an average 10%.There was nervousness ahead of a pivotal meeting of the Organization of Petroleum Exporting Countries (OPEC) on Thursday, when members will face a tough decision over whether to cut output in the wake of a 30% slump in crude prices since June.Petrofac's share price had crashed over 25% after the company scaled back its profit assumptions for next year, saying that depressed oil prices and the timing of deliveries will result in a weaker bottom line.Chief executive Ayman Asfari said it has been a "difficult period for Petrofac and the industry" and that the company's execution on a number of its projects has "fallen short of the high standards we set for ourselves".Net profit for 2014 is now being guided to come in at the low end of the expected $580m-600m range, down from $650m in 2013. Furthermore, while Petrofac had previously forecast "strong earnings growth" for 2015, net profit next year is now only predicted to be just $500m.Every $1 movement in the oil price - currently trading at its lowest in four years - has a $2m impact on Petrofac's net profit, the company said.Analyst Tony Shepard from Charles Stanley said the update was "another disappointment after several earlier profit warnings". He said: "Unfortunately, there are still too many uncertainties over the outlook including weak cash flow and strategy."Others in the oil services sector were also taking a hit from negative read-across, including Greka Drilling, Hunting, Amec Foster Wheeler, Wood Group, GETECH and Lamprell.Meanwhile, the OPEC meeting, which will be held in Vienna at the organisation's headquarters, is expected to divide OPEC's 12 members over the decision whether or not to cut output, prompting investors to tread cautiously in London.Any further weakness in the oil price could prompt oil exploration and development companies to scale back spending on projects, sparking concerns about demand in the oil services sector.OPEC, which produces around a third of global crude output with a target of 30m barrels per day, is "stuck between a rock and a hard place", according to analyst Connor Campbell from Spreadex."If they cut production the US can consume more of the market share, and become less reliant on the oil cartel; if they don't, oil's fall will be swift and unforgiving. We won't know until Thursday what side OPEC's coin toss will land," he said. Top performing sectors so far todayFixed Line Telecommunications 4,464.78 +2.99%Health Care Equipment & Services 6,376.56 +2.89%Industrial Metals & Mining 1,534.85 +1.72%Automobiles & Parts 7,874.61 +0.90%Electronic & Electrical Equipment 3,790.10 +0.70%Bottom performing sectors so far todayOil Equipment, Services & Distribution 20,214.48 -9.72%Industrial Transportation 2,707.97 -1.68%Mining 15,450.86 -1.68%Food Producers & Processors 7,957.39 -1.27%Mobile Telecommunications 5,057.50 -1.10%