For the US or for the world, or just for Libya, Nigeria, or the Middle East?
DOE (Dept. of Energy) Cushing OK Crude Inventory is given every Wednesday, on CNBC at 10:30 am EST and other media outlets.
Also, the US Energy Information Admin
Short-Term Energy Outlook
http://www.eia.gov/forecasts/steo/report...
Here is one study on crude oil supply and demand.
http://www.yardeni.com/pub/globdemsup.pd...
If you just want historical prices for crude oil, rather than supply and demand data, there are lots of places on the web. You only get 5 days maximum futures data on Yahoo.
http://finance.yahoo.com/echarts?s=CLN14...
But you can download a free trial of a good trading platform called NinjaTrader, and through AMPFutures the futures data feed is free. Build your own database.
http://ampfutures.com/
Demand and Supply are represented on a chart as Support and Resistance using technical analysis, a foundational approach of analysis of commodities.
http://stockcharts.com/help/doku.php?id=...
Or maybe you are asking about the COT Report. (Commitment of Traders)
http://www.cftc.gov/MarketReports/Commit...
i want to trade crude oil futures. Where i can find demand and supply data ?