Denmark's AP Moller-Maersk said for the first time Thursday there was a risk it could lose its largest oil producer, a 300,000 barrel per day Qatari field, and may not replace the production by buying other assets.Chief Executive Nils Smedegaard Andersen's comments give some insight into Maersk's view of how the oil industry will evolve, after oil prices more than halved in the past two years.The recently-streamlined conglomerate still considers Maersk Oil as core to its business and for years the expectation was that the Qatar field would be part of this as Maersk would renew a 25-year production agreement when its licence ran out in 2017.But the Gulf state surprised the company last year by putting out a tender for the Al Shaheen field, which Maersk Oil has been operating since 1992.