MOSCOW, Jan 20 (Reuters) - Oil production at Kazakhstan's vast Tengiz oilfield, one of the world's largest, could be halted for another 7-10 days after shutting down on Sunday, cutting crude exports via the Caspian Pipeline ​Consortium, three industry sources told Reuters. Operator Tengizchevroil (TCO) said on Monday that production at the Tengiz and Korolevskoye fields had been ‌stopped because of power supply problems. A day earlier, on January 18, a fire broke out at two turbine transformers at the f ...