U.S. oil and gas supermajor Chevron signed an agreement in principle last week with Iraq’s Oil Ministry for the development of the huge Nasiriyah oil field, plus other oil producing fields and exploration sites. This is the latest in a recent line of top-tier Western firms that have announced a return to Iraq following a collective exodus from the country beginning around seven years ago with ExxonMobil’s withdrawal from the crucial Common Seawater Supply Project (CSSP). ExxonMobil itself is currently in discussions with Iraq’s…