The oil and gas sector is one of today's best performers, helped by a rally in BP shares.The oil giant has cancelled dividends for the rest of the year and agreed to a demand from US president Obama to put $20bn in an escrow account to cover claims resulting from the oil spill in the Gulf of Mexico.The UK company will pay $3bn into the escrow account in the third quarter of 2010 and $2bn in the fourth quarter. This will by followed by payments of $1.25bn a quarter until a total of $20bn has been reached.Elsewhere in energy, shares in GTL have given up gains that came yesterday after the ethanol producer said higher production and improved margins helped ethanol producer GTL Resources more than double profits in the year to March 31.It is the worst performer in the alternative energy sector, one of today's worst performers.Top performing sectors so far todayBanks 4,845.40 +2.21%Oil & Gas Producers 6,871.97 +2.15%Chemicals 5,224.26 +1.71%Household Goods & Home Construction 6,217.89 +1.62%Automobiles & Parts 3,016.10 +1.10%Bottom performing sectors so far todayAlternative Energy 5,788.73 -2.30%Electricity 6,526.93 -1.26%Gas, Water & Multiutilities 4,087.88 -0.70%Oil Equipment, Services & Distribution 17,667.65 -0.70%Food Producers & Processors 5,003.86 -0.52%