LONDON/MOSCOW, Jan 16 () - Offer prices for Caspian CPC Blend crude oil dropped sharply this week, according to trade sources, as exports of the grade continue to be impacted by drone strikes in the Black Sea and weather-related delays.  ExxonMobil, which is a shareholder in the Caspian Pipeline Consortium, was offering on Thursday a 120,000 metric ton CPC Blend cargo at a $1.35 a barrel discount to benchmark dated Brent in the Platts window, a service run by oil-index publisher S&P Global