Oil trading major Glencore has been buying spot cargoes of Middle Eastern crude grades for a Singaporean refinery it has recently acquired from Shell, anonymous traders have told Bloomberg. Glencore has bought in recent weeks at least three cargoes of Qatar’s Al-Shaheen crude and at least one of Abu Dhabi’s Upper Zakum of 500,000 barrels each for February loading, according to Bloomberg’s sources. Glencore is expected to be a more active player in the physical oil market going forward as it is now procuring crude for the Bukom…