Billionaire Saudi Prince Alwaleed bin Talal has warned shale oil and gas development poses a threat to the kingdom's economy, the Wall Street Journal's Summer Said reports. In an open letter to Saudi oil minister Ali al Naimi [in Arabic], Alwaleed also warns the kingdom must diversify its revenue streams in the face of flagging oil demand. A source translated the key portion of the note: With all due respect to your Highness’ viewpoint about shale gas and that it poses no danger on Saudi economy at ‘the present time’, I was hoping that your Highness would also shed light...