Rising crude prices and deal activity pushed stocks in the oil and gas sector higher on Wednesday.Brent crude prices were up a further 0.1% at $133.58 a barrel today, extending recent gains, as markets reacted to the latest geopolitical developments in Iraq. Islamist-led militants have attacked Iraq's biggest oil refinery in Baghdad with machine guns and mortars, according to reports. Also pushing the price of oil higher was data from the American Petroleum Institute which showed that crude inventories in the US fell by 5.7m barrels in the week ended June 13th.Oil major BP was in demand, rising 1%, after announcing a £12bn deal with state-owned China National Offshore Oil Corporation (CNOOC) to supply up to 1.5m tons of liquefied natural gas (LNG) over 20 years, starting in 2019.The deal is expected to be signed in London today as Chinese Premier Li Keqiang meets Prime Minister David Cameron on his three-day visit to Britain.CNOOC also signed a global strategic alliance agreement with UK-listed Royal Dutch Shell, through which they will explore "co-operation opportunities". The news helped Shell's shares 1.7% higher this afternoon.Investors were also reacting to yesterday's announcement by Shell that it is to raise around $5bn after tax through the sale of a hefty chunk of its stake in Australian energy group Woodside Petroleum. Meanwhile, Shell also revealed plans to float its Midstream subsidiary on the New York Stock Exchange later this year.Others in the sector such as Union Jack Oil, Range Resources, Victoria Oil & Gas and Xcite Energy were also performing well today.Top performing sectors so far todayIndustrial Metals & Mining 1,129.22 +2.70%Forestry & Paper 11,536.12 +1.32%Oil & Gas Producers 8,761.84 +1.31%Mobile Telecommunications 4,464.06 +1.05%Industrial Transportation 2,890.71 +0.90%Bottom performing sectors so far todayBeverages 14,380.12 -1.26%Oil Equipment, Services & Distribution 24,191.43 -0.48%Media 6,018.15 -0.41%Gas, Water & Multiutilities 5,948.84 -0.37%Financial Services 7,943.08 -0.29%BC