Provincial leaders are threatening to seize authority over several oil fields in Basra as a way to pay bills and fund investment in Iraq’s impoverished oil capital.Last week in Istanbul, the chairman of the council’s energy committee, Ali Shaddad al-Faris, held meetings with international lawyers to map out a legal strategy for claiming and contracting fields, according to an official familiar with the discussions.Sabah al-Bezzouni, the chairman of the Basra Provincial Council, said in a…